tag:blogger.com,1999:blog-46755403948504332212024-03-15T01:16:06.248-07:00Waxing PaleontologicalZachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.comBlogger47125tag:blogger.com,1999:blog-4675540394850433221.post-20475789198866898832021-01-14T13:07:00.133-08:002021-01-14T14:44:49.370-08:00Hopeful Pterosaur(omorph)s<span id="docs-internal-guid-45a563e2-7fff-0a47-636d-fe0f5cf1a6f9"><span style="font-family: times;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8eWVKmIerJI2MUL9v7GYdMH06qybbU0GoZhZbsisMSVNCWKGQdGm91rZ92CVj_M8Rfb-eOmX_G8_m6-o2s35VEXNl6-keTAOVFZNHg4CnCWyU2WYzuBJIksGUAtiuLAoH8fCgvPElOaQ/s1000/Lagerpetid+by+Rodolfo+Nogueira.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="563" data-original-width="1000" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8eWVKmIerJI2MUL9v7GYdMH06qybbU0GoZhZbsisMSVNCWKGQdGm91rZ92CVj_M8Rfb-eOmX_G8_m6-o2s35VEXNl6-keTAOVFZNHg4CnCWyU2WYzuBJIksGUAtiuLAoH8fCgvPElOaQ/s320/Lagerpetid+by+Rodolfo+Nogueira.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;">Lagerpetid by Rodolfo Nogueira</span></td></tr></tbody></table><p></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; white-space: pre-wrap;">As we’ve seen, the Triassic was a period filled with all manner of charismatic animals, including </span><a href="https://waxing-paleontological.blogspot.com/2019/01/whale-lizards-of-triassic-iii-revenge.html" style="font-size: 11pt; white-space: pre-wrap;" target="_blank">reptilian platypuses and whales</a><span style="font-size: 11pt; white-space: pre-wrap;">, </span><a href="https://waxing-paleontological.blogspot.com/2015/12/drepanosaurs-primer.html" style="font-size: 11pt; white-space: pre-wrap;" target="_blank">praying mantis-like drepanosaurs</a><span style="font-size: 11pt; white-space: pre-wrap;">, </span><a href="https://waxing-paleontological.blogspot.com/2016/11/from-triassic-monster-manual.html" style="font-size: 11pt; white-space: pre-wrap;" target="_blank">semi-aquatic dragons</a><span style="font-size: 11pt; white-space: pre-wrap;">, </span><a href="https://waxing-paleontological.blogspot.com/2018/06/faux-theropods.html" style="font-size: 11pt; white-space: pre-wrap;" target="_blank">pseudosuchian dinosaur mimics</a><span style="font-size: 11pt; white-space: pre-wrap;">, and everything in between. We have not, however, in our Triassic adventures, yet directly touched on the typical touchstones of Mesozoic diversity: pterosaurs and dinosaurs. In part, that has been intentional: why focus on dinosaurs when there are so many other wonderful animals to learn about during the Triassic? But another, perhaps more interesting, reason is that dinosaurs and pterosaurs simply weren’t a particularly large or diverse component of Triassic ecosystems until the very end. I would argue that the dinosaur's reign didn’t really begin until the Triassic-Jurassic extinction event removed their pseudosuchian competitors. Pterosaurs, too, diversified during the Jurassic, although I'm not sure if anything was keeping them down before. Anyway, until the Jurassic, these would-be prehistoric paragons were living in the shadows of predatory rauisuchians, herbivorous aetosaurs, </span><a href="https://waxing-paleontological.blogspot.com/2019/01/big-finish-to-2018.html" style="font-size: 11pt; white-space: pre-wrap;" target="_blank">giant dicynodonts</a><span style="font-size: 11pt; white-space: pre-wrap;">, and semi-aquatic phytosaurs. No revolution, however, comes from nothing. Dinosaurs and pterosaurs had ancestors too, and in this essay, we’ll focus on one their most distant relatives, the lagerpetids.</span></p><div></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span></span></p><a name='more'></a></span></span><p></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: times;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Remember that the Archosauria, which today consists of crocodilians and birds, got its start during the Middle Triassic, when those two branches split. The bird line, called the Avemetatarsalia, got its start with </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/316055576_The_earliest_bird-line_archosaurs_and_the_assembly_of_the_dinosaur_body_plan" target="_blank">Teleocrater</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/316055576_The_earliest_bird-line_archosaurs_and_the_assembly_of_the_dinosaur_body_plan" target="_blank"> and its aphanosaur cousins</a>, who are the earliest known members of that large group. Non-aphanosaur avemetatarsalians are called ornithodirans, which means “bird necks,” named (by Gauthier in 1986) for the common ancestor of pterosaurs and dinosaurs (and all its descendants), which tend to have S-curved necks.</span></span></p><span style="font-family: times;"><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Within Ornithodira, there are two clades: Pterosauromorpha, which unambiguously includes all pterosaurs, and the Dinosauromorpha, which contains a hodgepodge of dinosaur-like animals, including the silesaurids, <a href="https://waxing-paleontological.blogspot.com/2016/12/hopeful-dinosaurs.html" target="_blank">who we’ve met before</a>, and who may in fact be <a href="http://waxing-paleontological.blogspot.com/2020/09/slightly-more-hopeful-dinosaurs.html" target="_blank">basal ornithischian dinosaurs</a>, and an animal called </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.biodiversitylibrary.org/page/4306596#page/485/mode/1up" target="_blank">Lagosuchus</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> (or </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.1994.10011538" target="_blank">Marasuchus</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">) (or </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.semanticscholar.org/paper/THE-VALIDITY-OF-LAGOSUCHUS-TALAMPAYENSIS-ROMER%2C-THE-Agnol%C3%ADn-Ezcurra/5263d0a3bdfae66c649bbdfe2cc7b6b13bb2f32f" target="_blank">Lagosuchus</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.semanticscholar.org/paper/THE-VALIDITY-OF-LAGOSUCHUS-TALAMPAYENSIS-ROMER%2C-THE-Agnol%C3%ADn-Ezcurra/5263d0a3bdfae66c649bbdfe2cc7b6b13bb2f32f" target="_blank"> after all</a>). Other players in the ornithodiran story are an animal in a perpetual state of reassessment called </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and the topic of today’s essay: lagerpetids.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpetids are generally small, bipedal animals that would have superficially resembled very small theropods at first glance. While we once thought that all lagerpetids were itty-bitty, that view is changing thanks to recent discoveries. Their geographic range is impressive, having been found in Brazil, Argentina, Texas, Arizona, and Madagascar (so far). Perhaps the most frustrating aspect of this group is they are often known primarily through leg bones, because the leg (and specifically the femur) is the most-often preserved part of the skeleton for some reason. One lagerpetid genus, which includes three species, is known from leg bones alone!</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><div style="text-align: left;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoM9AHKIdT06NAuOzCuyJiHMZMo3sLZMFHiZ5FbWHjtmik1vT-Mpea1xIcalulDQ1dr5Bfi9LMRferKqKKkZJ7budiBORjdylPBijGQRm_hIVS8uPrFbYDFoR7Z7BAk91fqwg5JywvzJQ/s902/Lagerpeton+Romer+1971.bmp" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="902" data-original-width="679" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoM9AHKIdT06NAuOzCuyJiHMZMo3sLZMFHiZ5FbWHjtmik1vT-Mpea1xIcalulDQ1dr5Bfi9LMRferKqKKkZJ7budiBORjdylPBijGQRm_hIVS8uPrFbYDFoR7Z7BAk91fqwg5JywvzJQ/w151-h200/Lagerpeton+Romer+1971.bmp" width="151" /></a></span></div><span style="font-size: 11pt; white-space: pre-wrap;">T</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">he first lagerpetid ever discovered was </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton chanarensis</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> from Argentina, named and preliminarily described by prominent paleontologist Alfred Romer in 1971; he also named </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagosuchus talampayensis</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, who we’ll meet in a future essay, in the same paper. The </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> fossil in question is a complete, articulated hindlimb (right). Romer referred an additional specimen to </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagosuchus </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://archive.org/details/cbarchive_40458_thechanaresargentinatriassicre1952" target="_blank">the following year</a> based on material preserved on two slabs that also contained a cynodont (Romer, 1972). <a href="https://www.jstor.org/stable/4523529?seq=1" target="_blank">Sereno & Arcucci</a> (1993) would later clarify that, of the many bones preserved in these slabs, only the fragmentary left and right femora can be unambiguously referred to </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">--and so the pattern begins. Additional specimens were described in the following years by <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.1984.10011976" target="_blank">Bonaparte</a> (1984) and <a href="https://paleoglot.org/files/Arcucci_86.pdf" target="_blank">Arcucci</a> (1986). All told, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is known from its hindlimb, pelvis, sacrum, some posterior dorsal vertebrae, and anterior caudal vertebrae. As we’ll see, that’s pretty good for a lagerpetid.</span><p></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> has a unique femur that will later become diagnostic for the whole family: the head of the femur is notably hook-shaped. Additional unique features include a blade-shaped flange (later called a “pubo-ischiadic plate”) connecting the pubis and ischium, and ankle bones (astragalus & calcaneum) that are partially co-ossified. The foot of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is unique among not just ornithodirans, but reptiles generally: the first toe (dewclaw) is very short, as would be expected, but the second toe is also short and may not have reached the ground while </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">was walking around (assuming it walked--read on). Instead, the third and fourth toes are quite long--the fourth is a bit longer--and gives </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> a distinctly didactyl foot.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">A few other oddities are worth mentioning: the neural spines of the preserved dorsal vertebrae are angled forward, which is unique among archosaurs, and the pelvis is surprisingly small (especially front-to-back) relative to the length of the hindlimb.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><div style="text-align: left;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcB9P7OEAH5htajG2uUaRooXKJUXP2b0mrNlpixqtplWHnmtngVxmY-vPrtVugXosNbu03JNbobsAJHXzUu2RaRjCNOcs3Mclfx9rrpT95Gfuepax3w7iD7_fUVye5d312lCBXjYFjWTM/s1913/Lagerpeton+%2528Sereno+%2526+Arcucci%252C+1993%2529.bmp" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1913" data-original-width="1018" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcB9P7OEAH5htajG2uUaRooXKJUXP2b0mrNlpixqtplWHnmtngVxmY-vPrtVugXosNbu03JNbobsAJHXzUu2RaRjCNOcs3Mclfx9rrpT95Gfuepax3w7iD7_fUVye5d312lCBXjYFjWTM/s320/Lagerpeton+%2528Sereno+%2526+Arcucci%252C+1993%2529.bmp" /></a></span></div><div style="text-align: left;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">In light of these unique features, Sereno & Arcucci (1993) hypothesize that </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;"> was a hopper, or saltator. “Several characters in </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">L. chanarensis</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">,” they write, “in particular, are consistent with saltatory habits, although none are conclusive.” In bipedal saltatorial mammals, anteriorly-angled neural spines on the posterior lumbar vertebrae may provide better leverage for the muscles that support the trunk. Regarding the small pelvis, “there is some suggestion in saltatory rodents that shortening of the distance from pelvic girdle to femur enhances force production during hip extension.” The functionally didactyl foot, too, “may increase the strength of the distal segment of the hind-limb without increasing its weight.” Their reconstruction of the <i>Lagerpeton </i>material is at the left. The saltator hypothesis is a good one for smaller members of the family, but we might question its applicability towards larger lagerpetids. </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">While Romer (1971) considered </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;"> (and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">Lagosuchus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">) to be “pseudosuchians,” he did recognize that they were both “in some fashion...leading toward the dinosaurs and, particularly, towards the coelurosaurian group of the Saurischia.” It should be noted that Romer’s concept of “pseudosuchians'' was more of generic mish-mash of unrelated archosaur grpi[s instead of the diagnostic, monophyletic group it is today. Furthermore, his conception of dinosaurs was similarly broad. At the time, it was widely thought that different groups of dinosaurs originated from different archosaur “stock.” For example, coelurosaurs had different ancestors than did the “carnosaurs,” or larger theropods. Ornithischians, sauropods, and even basal sauropodormophs like </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;">Plateosaurus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline;"> (“prosauropods”) all had different ancestors, making the “Dinosauria” something of a useless concept.</span></span></div><p></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Today, we utilize more restrictive definitions for these groups, but Romer was basically correct in his reasoning: </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> really was “leading towards the dinosaurs” (as opposed to, say, crocodiles).</span></p><div><span style="font-family: times;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnhy3iTdLXD64uJEyVcYe4ggrppcAj5izoJEeruwFZ_aFvI0hApa3vqsOcV_dAk8JrS1DXb-sm8nn6aiecCaSIKGYrtu6xYgAwTof_jTSUcLJlmRBMJyNSM_v2f5-PONwC3FVB2DZh9wU/s784/D.+romeri.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="496" data-original-width="784" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnhy3iTdLXD64uJEyVcYe4ggrppcAj5izoJEeruwFZ_aFvI0hApa3vqsOcV_dAk8JrS1DXb-sm8nn6aiecCaSIKGYrtu6xYgAwTof_jTSUcLJlmRBMJyNSM_v2f5-PONwC3FVB2DZh9wU/w400-h253/D.+romeri.jpg" width="400" /></a></div><div><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></div><div><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> remained a singular curiosity for more than thirty years years before another lagerpetid was described in 2007 by Randall Irmis and colleagues. That taxon, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/6197829_A_Late_Triassic_Dinosauromorph_Assemblage_from_New_Mexico_and_the_Rise_of_Dinosaurs" target="_blank">Dromomeron romeri</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, is from the Chinle Formation in New Mexico (above). As will become something of a trope for the group, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was described from only from leg bones. What’s arguably more important than the discovery of a second lagerpetid (although that’s still significant) is the authors’ finding that it existed alongside a silesaurid (</span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/279695075_A_review_of_the_systematic_position_of_the_dinosauriform_archosaur_Eucoelophysis_baldwini_Sullivan_Lucas_1999_from_the_Upper_Triassic_of_New_Mexico_USA" target="_blank">Eucoelophysis</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">) and a true dinosaur (</span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2019.1645682?journalCode=ujvp20" target="_blank">Chindesaurus</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">). “Our investigations,” they write, “have found the same co-occurrences in several other Chinle Formation and Dockum Group localities in Arizona, New Mexico, and Texas” (Irmis et al., 2007, p.361). Additionally, the age ranges of these sites indicate that lagerpetids, silesaurids, and true dinosaurs cohabitated for 15-20 million years. Indeed, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is from younger rocks than </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, suggesting this was a long-lived group. </span></div><div><span style="font-family: times;"><br /></span></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_NJsHuabOggW3AQQl_wq1En2savwIZ1ifKfyXqnI032KXg7PM6haliMSGs1oXxsRhNYrMA8llg8V_a-fTNtQi3Y2Z6_kTRhXrmT7uBK9nBUgz0Whbk1K1GocfOhn6xR3FELyVeJDXiGw/s2048/D.+gregorii.bmp" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="2048" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_NJsHuabOggW3AQQl_wq1En2savwIZ1ifKfyXqnI032KXg7PM6haliMSGs1oXxsRhNYrMA8llg8V_a-fTNtQi3Y2Z6_kTRhXrmT7uBK9nBUgz0Whbk1K1GocfOhn6xR3FELyVeJDXiGw/w400-h235/D.+gregorii.bmp" width="400" /></a></div></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">A second species of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/228351114_Hindlimb_Osteology_and_Distribution_of_Basal_Dinosauromorphs_from_the_Late_Triassic_of_North_America" target="_blank">D. gregorii</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, was named two years later for material from Texas’ Dockum Group (Nesbitt et al. 2009) (above). It is also known only from femora, but the authors documented a number of other leg bones, including toe bones, from both it and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, as well as assigning a number of specimens from other localities as belonging to </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> or Lagerpetidae generally. Intriguingly, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gregorii</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is known from a series of six femora which form a growth series. Finally, the authors formally defined the Lagerpetidae for the first time. I will note that Arcucci (1986) named the group “Lagerpetonidae” but he did not provide a phylogenetic definition.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/257448913_Vertebrate_Succession_in_the_Ischigualasto_Formation" target="_blank">Ricardo Martinez and colleagues</a> (2013) reported a lagerpetid femur fragment from Argentina’s famous Ischigualastro Formation, the “Valley of the Moon,” where one of the earliest dinosaurs, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Eoraptor</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, was discovered. Unfortunately limited to the distal end of the femur, the specimen provides little taxonomic information apart from “here be lagerpetids.”</span></p><div><span style="font-family: times;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRz6MqrkHmYw789SsUFO_TK5VbbKQ3_YwWqzpsxJwHKEevd5L5TexacNG_5vLlzmASdLuL-nYHCM0S6oW_hCxunTGZig1M5eP2UeCOUoQfFrfCueNxGx-ts42dDEyvclr-VZWpebBFeaU/s850/D.+gigas.png" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="658" data-original-width="850" height="155" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRz6MqrkHmYw789SsUFO_TK5VbbKQ3_YwWqzpsxJwHKEevd5L5TexacNG_5vLlzmASdLuL-nYHCM0S6oW_hCxunTGZig1M5eP2UeCOUoQfFrfCueNxGx-ts42dDEyvclr-VZWpebBFeaU/w200-h155/D.+gigas.png" width="200" /></a></div><div><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">2016 was a banner year for lagerpetids. Martinez et al. named a third species of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://bioone.org/journals/ameghiniana/volume-53/issue-1/AMGH.21.06.2015.2894/A-Norian-Lagerpetid-Dinosauromorph-from-the-Quebrada-Del-Barro-Formation/10.5710/AMGH.21.06.2015.2894.short" target="_blank">D. gigas</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, from Ischigualastro (left). The holotype is a single femur preserved in two pieces--a small section of the mid-shaft is missing. However, it is extremely similar to </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> specimens from the United States. </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gigas</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was quite a bit larger than any other lagerpetid known at the time, however: With a femur length of 7.5 inches, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gigas </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">was more than twice the size of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">’s 3 inch femur. </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gigas</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, at least, grew to be as large as some silesaurids.</span></div><div><span style="font-family: times;"><br /></span></div><div><span style="font-family: times;"><br /></span></div><div><span style="font-family: times;"><br /></span></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy05_Zl3ayeIrKlDyBl83sVvO7OHMDcwEpIsW1BgOuPy3Gj7iZ1nsa6FRdfsK9hyxkJyiRHy3s5XOz-nQhdU3tSRqWEyo7zWj1bFigbSXN-zaunXZpmDUx46Ys5VP2OTO3f39_sj3T848/s1634/Ixalerpeton.bmp" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1634" data-original-width="1133" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy05_Zl3ayeIrKlDyBl83sVvO7OHMDcwEpIsW1BgOuPy3Gj7iZ1nsa6FRdfsK9hyxkJyiRHy3s5XOz-nQhdU3tSRqWEyo7zWj1bFigbSXN-zaunXZpmDUx46Ys5VP2OTO3f39_sj3T848/s320/Ixalerpeton.bmp" /></a><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></div><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The second lagerpetid published that year was </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/309896337_A_Unique_Late_Triassic_Dinosauromorph_Assemblage_Reveals_Dinosaur_Ancestral_Anatomy_and_Diet" target="_blank">Ixalerpeton polesinensis</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, from the Santa Maria Formation of Brazil (Cabriera et al. 2016) (right). It was found in the same quarry as the basalmost sauropodomorph dinosaur, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/325158622_Early_evolution_of_sauropodomorphs_anatomy_and_phylogenetic_relationships_of_a_remarkably_well-preserved_dinosaur_from_the_Upper_Triassic_of_southern_Brazil" target="_blank">Buriolestes schultzi</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, and briefly described in the same paper. </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is arguably the most important lagerpetid found so far, as its beautifully-preserved remains include many bones never before described for a lagerpetid, including a complete series of dorsal and sacral vertebrae, the front third of the tail, the back half of the cervical series, parts of the skull roof and braincase, and a scapula and humerus. Unfortunately, these remains have not been fully described. It appears to be quite small, though, with a femur length comparable to </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">. Once it is fully described, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> will be able to fill in a lot of blanks regarding the anatomy of lagerpetids.</span><p></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">There was one more noteworthy lagerpetid paper published in 2016--<a href="https://palaeo-electronica.org/content/2016/1498-dockum-basal-dinosauromorphs" target="_blank">Sarıgül</a> reported additional femora from </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gregorii</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> from the lower member of the Dockum Group. Especially in the case of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, this demonstrates that </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> “existed during most of the Late Triassic” (Sarıgül, 2015). Furthermore, the paper documents the first co-occurrence of the two species of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">. Previously, the two had been reported from successive rock units and did not overlap in time, but these new discoveries show that the hypothesized replacement of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gregorii</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> by </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> later in the Triassic must be incorrect if the latter had been around the whole time. In fact, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. gregorri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> appears to have gone extinct long before </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">D. romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> did.</span></p><div><span style="font-family: times;"><br /></span></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/323630340_Ingroup_relationships_of_Lagerpetidae_Avemetatarsalia_Dinosauromorpha_A_further_phylogenetic_investigation_on_the_understanding_of_dinosaur_relatives" target="_blank"></a></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij7Y3RR3935lU6avZBTbCbezmbAe3P4MglxMirHvD0maEBF_D2g0hzYR9xlfiGNwsa85rwF-V8osYZ7UfJtP7d0EBd7MEQenSkWqWogYuIvrhYsv7c4-72hSGaPTI_oQIwlKsvubfWAQU/s1816/Lagerpetids.bmp" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1356" data-original-width="1816" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij7Y3RR3935lU6avZBTbCbezmbAe3P4MglxMirHvD0maEBF_D2g0hzYR9xlfiGNwsa85rwF-V8osYZ7UfJtP7d0EBd7MEQenSkWqWogYuIvrhYsv7c4-72hSGaPTI_oQIwlKsvubfWAQU/s320/Lagerpetids.bmp" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;">Known lagerpetids from Muller et al. (2018)</span></td></tr></tbody></table><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/323630340_Ingroup_relationships_of_Lagerpetidae_Avemetatarsalia_Dinosauromorpha_A_further_phylogenetic_investigation_on_the_understanding_of_dinosaur_relatives" target="_blank"><br />Muller et al.</a> attempted the first in-group phylogeny of lagerpetids in 2018, using data from all six known species and Specimen PVSJ 883 from Martinez et al. (2012). They found that </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was the basalmost member of the group (and also the oldest) while </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was the most derived, longest-lived, and youngest taxon.</span><p></p><div><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The next year, <a href="https://www.sciencedirect.com/science/article/abs/pii/S089598111830525X" target="_blank">Garcia et al.</a> (2019) published an extensive description of the fauna of Brazil’s Santa Maria Formation where a variety of dinosauromorphs lived together, including a new (but unnamed) lagerpetid. Although concurrent with the rocks that produced </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, the new lagerpetid--known from a distal femur fragment--does appear to be distinct. The authors also report that, through successive faunal assemblages, lagerpetids, silesaurids, and basal dinosaurs lived together for at least 21 million years, similar to the situation in North America at this time.</span></div><div><span style="font-family: times;"><br /></span></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguS7trdaJdrh7WSZSrZ7heJf3n7uxCJasE99-Kne7hk7MuCrVKceGJTZb_9gJDh6PrtADfe0YkFbajpgBQtPm58zUbwrpn9iNPUTDaM3sTvKPF471s3r8Fq7DLNHIMMulEDXA1iguEOXs/s1800/Kongonaphon.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1184" data-original-width="1800" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguS7trdaJdrh7WSZSrZ7heJf3n7uxCJasE99-Kne7hk7MuCrVKceGJTZb_9gJDh6PrtADfe0YkFbajpgBQtPm58zUbwrpn9iNPUTDaM3sTvKPF471s3r8Fq7DLNHIMMulEDXA1iguEOXs/s320/Kongonaphon.jpg" width="320" /></a></span></div><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">As reported by Kammerer et al. (2020), lagerpetids also lived on Madagascar. This team described the smallest lagerpetid yet--little </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.pnas.org/content/117/30/17932" target="_blank">Kongonaphon kely</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is, like so many of its relatives, known primarily from a femur, but other fragments of the skeleton were also found, including a maxilla bone with several teeth (above). The extremely small size of this animal is evident from the femur, which, at 38 mm long, is almost half the size of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> (77.8 mm). Perhaps this tiny individual was a baby or juvenile? To test that idea, the authors put a slice of the femur under the microscope to estimate its age, and found that its growth had slowed and was most likely an adult. They do note, however, that </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Kongonaphon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> may have been able to reach larger sizes, but given that they only have one example of it, it’s hard to say.</span><p></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The teeth of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Kongonaphon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> are the first teeth recorded for a lagerpetid and show wear patterns consistent with an insectivorous diet. Given that lagerpetids tend to be smaller animals, this isn’t terribly surprising, but good to have confirmed.</span></p><div><span style="font-family: times;"><br /></span></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyDKeC-To6LpQUN_ljvuOU_kP2aWiu-3YaOm9UxIaGiS8v2fiR419XlgZkfhFNj8VQqkwwd37bD_L5_PCljclPn-aCLZbQVpCVwstKPzXyflGjhmjPMjubxUfjJFpcU-nCSvR46hTyoks/s2030/Big+Lagerpetid.bmp" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="724" data-original-width="2030" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyDKeC-To6LpQUN_ljvuOU_kP2aWiu-3YaOm9UxIaGiS8v2fiR419XlgZkfhFNj8VQqkwwd37bD_L5_PCljclPn-aCLZbQVpCVwstKPzXyflGjhmjPMjubxUfjJFpcU-nCSvR46hTyoks/s320/Big+Lagerpetid.bmp" width="320" /></a></span></div><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br />More evidence for dinosauromorph cohabitation was reported by <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2020.1765788?journalCode=ujvp20" target="_blank">Beyl et al.</a> (2020). This team looked at a new site in the Santa Maria Formation in New Mexico and documented the animals living there. Among the various reptiles are several surprisingly large individuals of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> (species unknown) represented by fragmentary hindlimb elements--as per tradition--and a silesaurid. When scaled against other </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> femora, one individual (NMMNH P-18091) would have been as large or larger than the early theropods </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Chindesaurus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Coelophysis </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">(above)</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">! “Unless new discoveries provide evidence for a unique lagerpetid ecological niche,” they write, “their large-bodied forms may have competed with small-bodied carnivorous dinosaurs for prey.”</span><p></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The point, of course, is that dinosauromorphs did not go through periods of replacement, where more derived species simply outcompeted their predecessors. It’s clear that, in many areas, these animals all lived alongside each other, and must have occupied unique ecological roles to avoid direct competition. Intriguingly, lagerpetids occupy a large spectrum of body sizes, from extremely small (</span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Kongonaphon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">) to the size of early theropods (NMMNH P-18091). One would assume that, as lagerpetids increased in size, the hopping gait advocated by Sereno & Arcucci (1993) would eventually become less favorable unless they switched from a kangaroo rat method to something more akin to wallabies. I will note, however, that most lagerpetids, and certainly the largest of them, are known only from fragmentary hindlimb remains, so any more skeletal adaptations in favor of a saltatory lifestyle may simply be unknown at this time.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">For most of their paleontological history, lagerpetids were thought to be closer relatives of dinosaurs than pterosaurs, forming the basalmost group of a clade called Dinosauromorpha. This position has been advocated by <a href="https://www.researchgate.net/publication/233117665_Basal_Archosaurs_Phylogenetic_Relationships_and_Functional_Implications" target="_blank">Sereno (1991)</a>, Sereno & Arcucci (1993), <a href="https://www.researchgate.net/publication/228652912_The_higher-level_phylogeny_of_Archosauria_Tetrapoda_Diapsida" target="_blank">Brusatte et al. (2010)</a>, <a href="https://www.researchgate.net/publication/232678368_The_Early_Evolution_of_Archosaurs_Relationships_and_the_Origin_of_Major_Clades" target="_blank">Nesbitt (2011)</a>, <a href="https://peerj.com/articles/1778/" target="_blank">Ezcurra (2016)</a>, Cabreira et al. (2016), and Muller et al. (2018), and I'm sure I'm forgetting some. Nesbitt (2011), however, did note that the ankle structure of lagerpetids more closely resembled the basal pterosaur </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dimorphodon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> than dinosaurs. However, he considered that convergence and did not outweigh all the other features which tied lagerpetids to other dinosauromorphs.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">In their description of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Kongonaphon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, however, Kammerer et al. (2020) recovered lagerpetids in an intriguing, though weakly-supported, position:</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">“In analyses where </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was not included, Lagerpetidae was recovered in its traditional position...as the earliest-diverging clade of dinosauromorphs. When </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> was included, this genus and Lagerpetidae were both recovered as early-diverging pterosauromorphs (with </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> as the sister-taxon of Pterosauria).” The authors suggest caution, and that more complete lagerpetid specimens will be required to more fully vet this idea. “At present,” they write, “we...prefer to depict the base of Ornithodira as an unresolved polytomy between Lagerpetidae, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Sclermochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, Pterosauria, and Dinosauriformes.” (Kammerer et al., page 3).</span></p><div><span style="font-family: times;"><br /></span></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4r2bbsX6v5M51PsRBns-uSN-IJt6sSqYihPWEj5T9f0cPQvOORwiwdua9VtOI-90b5EA0gnsZW5_kVePQd4lpz5eXoOQLQnnrfqf022hCDkcoJBgiGqPLJ0X4zWbNQHXuOD7e80hXS1c/s1024/Scleromochlus.jpeg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="626" data-original-width="1024" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4r2bbsX6v5M51PsRBns-uSN-IJt6sSqYihPWEj5T9f0cPQvOORwiwdua9VtOI-90b5EA0gnsZW5_kVePQd4lpz5eXoOQLQnnrfqf022hCDkcoJBgiGqPLJ0X4zWbNQHXuOD7e80hXS1c/s320/Scleromochlus.jpeg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;"><i>Scleromochlus</i> as a doswellid, by Matt Celeskey</span></td></tr></tbody></table><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">A rundown of the many issues surrounding </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><a href="https://www.researchgate.net/publication/40662545_Scleromochlus_taylori_and_the_origin_of_dinosaur_and_pterosaurs" target="_blank">Scleromochlus</a></span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is outside the scope of this essay, but for the most part, <a href="http://markwitton-com.blogspot.com/2014/08/scleromochlus-taylori-more-than-just.html" target="_blank">Dr. Mark Witton</a> has you covered. All I can add is that, since Mark's post, <a href="https://peerj.com/articles/8418/" target="_blank">Chris Bennett</a> (2020) has suggested that it is a saltatorial doswellid or something “outside of the clade containing the most recent common ancestor of Erythrosuchidae and Archosauria and all its descendants.” (Bennett, 2020, page 1).</span><p></p><div><br /></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Awaiting a more complete--or at least non-cast specimen--of </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, however, may be unnecessary (though still welcome), for Kammerer et al.’s wish for better lagerpetid data was not far off. At the blessed end of 2020, Ezcurra et al. brought a <a href="https://www.nature.com/articles/s41586-020-3011-4" target="_blank">treasure trove of lagerpetid material</a> to light (below), including endocasts from </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton </span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">and, surprisingly, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> that robustly supports a basal pterosauromorph position for Lagerpetidae.</span></p><div><span style="font-family: times;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGIncLVQp4NQZhxVhM6CV7LzSS5zf83ahhdyB6vVJuI06UNU98__j3xnEfY4fCnv6h3mUEA9186RsO5MO75e6VZRphP83reChF7uCOllGwNb27QouYNlsojLzqinpgpUOigNAWwBRHQzs/s806/Lagerpetid+Skeleton.jpg" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="533" data-original-width="806" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGIncLVQp4NQZhxVhM6CV7LzSS5zf83ahhdyB6vVJuI06UNU98__j3xnEfY4fCnv6h3mUEA9186RsO5MO75e6VZRphP83reChF7uCOllGwNb27QouYNlsojLzqinpgpUOigNAWwBRHQzs/s320/Lagerpetid+Skeleton.jpg" width="320" /></a></div><br /><div><span style="font-size: 11pt; white-space: pre-wrap;">Some of the more impressive similarities include:</span></div><br /><ul style="margin-bottom: 0px; margin-top: 0px; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Anterior tip of the dentary in </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and (!) </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> is toothless and comes to a point, as in early pterosaurs </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Seazzadactylus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Carniadactylus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Raetiodactylus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> (and, as we’ve seen, silesaurids). The dentary also curves downward towards its tip, as in </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Austriadactylus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Peteinosaurus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">.</span></p></li><li aria-level="1" dir="ltr" style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Contrary to most archosauriformes, lagerpetids and pterosaurs both have multicusped teeth and lack interdental plates.</span></p></li><li aria-level="1" dir="ltr" style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The endocasts for </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> are similar to, but not as developed as, early pterosaurs. The same can be said for the shape of the inner ears.</span></p></li><li aria-level="1" dir="ltr" style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">That pubo-ischiadic plate I mentioned occurs in </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Ixalerpeton</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">, and several early pterosaurs like </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Austriodraco</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> and </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dimorphodon</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">.</span></p></li><li aria-level="1" dir="ltr" style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Lagerpetids and early pterosaurs have hook-shaped femoral heads, and Nesbitt (2011) was right about their ankles, although in isolation, the ankle features themselves provide an ambiguous signal, as similar adaptations are found in silesaurids and some dinosaur groups.</span></p></li></ul><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">In all, Ezcurra et al. document features across the skeleton that connect lagerpetids to pterosaurs (some shown below). Interestingly, when the authors included </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Scleromochlus</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> in the analysis, it showed up as a sister taxon to the (Lagerpetidae + Pterosauria) clade.</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"><br /></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYEOYaNHkr5V4HncDnnhKXub7XiSFGxTmPwkxX16kFRfE-pfzCP0KAxlALPyJGUT0TIVcAU4jV1gH-JN8p_AVFvCdcjyuKpime0soTd0A0G3VnOV83C9-eZ7_x7YwKpAoBe9Ai9xWtWNc/s810/Lagerpetids+-+Pterosaurs.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="498" data-original-width="810" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYEOYaNHkr5V4HncDnnhKXub7XiSFGxTmPwkxX16kFRfE-pfzCP0KAxlALPyJGUT0TIVcAU4jV1gH-JN8p_AVFvCdcjyuKpime0soTd0A0G3VnOV83C9-eZ7_x7YwKpAoBe9Ai9xWtWNc/s320/Lagerpetids+-+Pterosaurs.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;">In each case, lagerpetid on the left pterosaur on the right.</span></td></tr></tbody></table><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">The authors note that the structural changes in the inner ear between lagerpetids and early pterosaurs mirrors the same transformation between non-avian theropods and birds. Do lagerpetids show any arboreal tendencies? Apparently </span><span style="font-size: 11pt; font-style: italic; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;">Dromomeron romeri</span><span style="font-size: 11pt; font-variant-east-asian: normal; font-variant-numeric: normal; vertical-align: baseline; white-space: pre-wrap;"> has strongly-recurved manual digits, suggesting to the authors that it may have used its forelimbs to capture prey, climb in trees, or both. “Our observations suggest that functional forelimb versatility became widespread in ornithodirans, allowing the evolution of disparate behaviours such as manual processing of food resources in dinosaurs and active flight in pterosaurs.” (Ezcurra et al., page 5).</span></p><div><span style="font-family: times;"><br /></span></div>This does not mean, of course, that lagerpetids ARE the ancestors of pterosaurs, but as an outgroup, they can give us insights into the transformations that must have taken place between the two groups. And in fact, r<span style="font-size: 11pt; white-space: pre-wrap;">ecognition of lagerpetids as basal pterosauromorphs still allows 18 million years for lagerpetid-like ancestors to develop into their final forms--I can only hope that representatives from that critical anatomical transition are one day discovered (or maybe they already have been, and are sitting in a museum someday).</span></span><br /><div><span style="font-family: times;"><span style="font-size: 11pt; white-space: pre-wrap;"><br /></span></span></div><div><span style="font-family: times;"><span style="font-size: 11pt; white-space: pre-wrap;">I apologize for the formatting weirdness in this post--I'm getting sick of wrestling with the HTML.</span></span></div>Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com2tag:blogger.com,1999:blog-4675540394850433221.post-61583077473412274342020-09-24T14:20:00.006-07:002020-12-10T13:16:12.215-08:00Slightly More Hopeful Dinosaurs<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheMefZlwtyqi6W_anvUTLEtAhmEBUVlA4Xvh2Sgqdu1sHl34HDJOdZIwiKjBMCNPbceXj3hDc3h5XqgKCM6ESSOWCG3fEvJ1adBzBTz7JCCLwNu1DTZrxAPNo0pCMa5yBL41v-A99IvLg/s850/Lewisuchus.png" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="708" data-original-width="850" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheMefZlwtyqi6W_anvUTLEtAhmEBUVlA4Xvh2Sgqdu1sHl34HDJOdZIwiKjBMCNPbceXj3hDc3h5XqgKCM6ESSOWCG3fEvJ1adBzBTz7JCCLwNu1DTZrxAPNo0pCMa5yBL41v-A99IvLg/s320/Lewisuchus.png" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;">Lewisuchus--basalmost ornithischian? (from <a href="https://www.researchgate.net/publication/335384605_New_Specimen_Sheds_Light_on_the_Anatomy_and_Taxonomy_of_the_Early_Late_Triassic_Dinosauriforms_from_the_Chanares_Formation_NW_Argentina" target="_blank">Ezcurra et al., 2019</a>)</span></td></tr></tbody></table><p>Dear me, it’s been awhile, hasn’t it? My tardiness in
keeping this blog going has not been entirely intentional; 2020’s been a year
for the records? I only hope it ends on December 31st and doesn’t
continue on in some space-time warping extension into December 32nd.
Nonetheless, I am motivated today to inform you all about a paper that brings
together several topics I’ve written about in years past: <a href="https://waxing-paleontological.blogspot.com/2016/12/hopeful-dinosaurs.html" target="_blank">silesaurids</a>, <i><a href="https://waxing-paleontological.blogspot.com/2017/08/and-then-there-were-none.html" target="_blank">Pisanosaurus</a></i>, and the <a href="https://waxing-paleontological.blogspot.com/2017/03/the-rise-possible-immediate-fall-of.html#more" target="_blank">Triassic Ornithischian Crisis</a>. Below, I will offer the briefest of recaps, but hit those
links if you want a more complete picture.</p><span><a name='more'></a></span><p>Silesaurids are a group of non-dinosaur dinosauriformes,
often found to be the immediate sister group to the Dinosauria. When the first
silesaurids were being described, it appeared that they had a toothless
predentary bone—an extra bone at the tip of the dentary that is unique to all
ornithischian dinosaurs. Thus, these early silesaurid descriptions included
speculation that silesaurids might represent the earliest ornithischian
dinosaurs.</p><p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal">More silesaurid taxa turned up over the next seventeen years
and it turns out that they are a diverse, widespread group of animals that may
or may not form a monophyletic group (depending on the phylogeny).
Additionally, their “predentary” bone is not a true predentary: The anterior
tip of their dentary bones are toothless and slightly upturned, yes, but are
not an entirely separate structure. The silesaurid “predentary” was more
readily explained as a similar adaptation for a group of herbivorous
non-dinosaurian dinosauriformes. It remains, however, a curious feature.</p><p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal">It’s also possible that silesaurids, as traditionally
envisioned, do not represent a monophyletic “Silesauridae,” but instead a
stepwise series of taxa between lagerpetids and true dinosaurs. Langer &
Ferigolo (<a href="https://www.researchgate.net/publication/236593137_The_Late_Triassic_dinosauromorph_Sacisaurus_agudoensis_Caturrita_Formation_Rio_Grande_do_Sul_Brazil_anatomy_and_affinities" target="_blank">2013</a>) take things a step farther, suggesting that while some
silesaurids are outside the Dinosauria proper, others really do represent the
oldest true ornithischian dinosaurs—including <i style="mso-bidi-font-style: normal;">Pisanosaurus</i>. Most analyses, however, have continued to find that
silesaurids—monophyletic group or otherwise—represent non-dinosaurian
dinosauromorphs.<o:p></o:p></p>
<p class="MsoNormal">Then, in 2017, <i style="mso-bidi-font-style: normal;">Pisanosaurus</i>
was reinterpreted as a silesaurid (<a href="https://www.researchgate.net/publication/318909984_Phylogenetic_reassessment_of_Pisanosaurus_mertii_Casamiquela_1967_a_basal_dinosauriform_from_the_Late_Triassic_of_Argentina" target="_blank">Agnolin & Rozadilla, 2017</a>). If true,
this would mean that there are <i style="mso-bidi-font-style: normal;">no</i>
unambiguous ornithischian taxa known from the entirety of the Triassic period. This
is surprising, but may be explained in part by the Ornithoscelida hypothesis,
which posits that some branch of the Theropoda and the entirety of Ornithischia
are sister groups to the exclusion of Sauropodomorpha (and herrerasaurids).
Baron (<a href="https://www.tandfonline.com/doi/abs/10.1080/08912963.2017.1410705?journalCode=ghbi20" target="_blank">2017</a>) suggested a few different scenarios to explain what was looking
like an Early Jurassic origin for ornithischians, including a position close to
<i style="mso-bidi-font-style: normal;">Chilesaurus</i>, but also touches on the
suggestions of Ferigolo & Langer (<a href="https://www.researchgate.net/publication/228366619_A_Late_Triassic_dinosauriform_from_south_Brazil_and_the_origin_of_the_ornithischian_predentary_bone" target="_blank">2006</a>) and Langer & Ferigolo (2013)
that at least some silesaurids represent basal ornithischians.<o:p></o:p></p>
<p class="MsoNormal">So, there are no Triassic ornithischians, there are no cats
in America, <i style="mso-bidi-font-style: normal;">Pisanosaurus</i> is apparently
a silesaurid, and silesaurids themselves are a group or grade of
non-dinosaurian dinosauriformes. Seems clear enough!<o:p></o:p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5oFzv2niwqGTmxLBwL0OBLOYOJGI9VtWh8yN9VRIx4VKsAAZlFltO-1Qa44hxdzDnN-mtQK1ssF0cHtmmeqN9WQYkh6nyZmZ55vcInBNBDkribh4KaCsbhIwzxqNCkq3nQFFY613e6RU/s1337/Paraphyletic+Silesauridae.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1337" data-original-width="1303" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5oFzv2niwqGTmxLBwL0OBLOYOJGI9VtWh8yN9VRIx4VKsAAZlFltO-1Qa44hxdzDnN-mtQK1ssF0cHtmmeqN9WQYkh6nyZmZ55vcInBNBDkribh4KaCsbhIwzxqNCkq3nQFFY613e6RU/s320/Paraphyletic+Silesauridae.jpg" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: x-small;">Muller & Garcia's (2020) Ornithischia, now featuring silesaurids</span></td></tr></tbody></table><p class="MsoNormal">Just a few weeks ago, <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0417" target="_blank">Muller & Garcia (2020)</a> provided a
full-throated endorsement of the “silesaurids as ornithischians” position,
bringing some phylogenetic support to the hypothesis. In their scenario,
silesaurids represent a paraphyletic series of stepwise taxa from the base of
Dinosauria towards the earliest genasaurs, represented by <i>Scuttelosaurus</i>. The authors show that silesaurid dentition also
seems to show a stepwise sequence from blade-shaped, insectivorous/carnivorous teeth to leaf-shaped, herbivorous teeth--similar to that of sauropodomorphs.</p><p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal">This hypothesis has two satisfying implications: it “solves”
the Triassic Ornithischian Crisis, as the oldest silesaurid is actually from
the Middle Triassic (<i style="mso-bidi-font-style: normal;">Asilisaurus</i>) and
it allows <i style="mso-bidi-font-style: normal;">Pisanosaurus</i> to be a silesaurid
and an ornithischian simultaneously. Indeed, in Muller & Garcia’s tree, <i style="mso-bidi-font-style: normal;">Pisanosaurus</i> is both the most derived
“silesaurid” and basalmost “traditional” ornithischian.<o:p></o:p></p>
<p class="MsoNormal">However, this idea presents new issues. For one, if <i style="mso-bidi-font-style: normal;">Asilisaurus</i> is an ancient ornithischian
dinosaur, that would pull the origin of the Dinosauria back to the Ansian. If <i style="mso-bidi-font-style: normal;">Nyasaurus</i> (<a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2012.0949" target="_blank">Nesbitt et al., 2013</a>) is a
true dinosaur (and not an ornithischian), that would help close the gap, as it
is coeval with <i style="mso-bidi-font-style: normal;">Asilisaurus </i>(and <i>Lutungutali</i>). If <i>Nyasaurus </i>isn't a dinosaur, however, there’s still a considerable gap in time between <i style="mso-bidi-font-style: normal;">Asilisaurus</i> and the next-oldest
non-ornithischian dinosaurs, which start showing up in the mid-Carnian.<o:p></o:p></p>
<p class="MsoNormal">The other issue—which might not be an actual issue—is that
silesaurids were long thought to be outside of Dinosauria because they lacked
certain features which define a monophyletic Dinosauria. If silesaurids are
true dinosaurs, it means that some of these defining features arose
independently in Ornithischia and Saurischia. However, given the amount of
homoplasy in dinosauromorphs, this might not be surprising or even
problematic. Muller & Garcia (2020) write that: </p><blockquote style="border: none; margin: 0px 0px 0px 40px; padding: 0px;"><p class="MsoNormal" style="text-align: left;">...the branch support and bootstrap values of the present topology are generally low...However, it is not surprising. Low values occur in other topologies (traditional Ornithischia/Saurischia split and Ornithoscelida hypothesis) obtained by distinct datasets. This condition is tentatively explained by high rates of homoplasy, as the earliest members of the major subgroups were very similar in body size and morphology.</p></blockquote><p>The authors use a recently-ereted clade name, "Sulcimentisauria" (<a href="https://peerj.com/articles/7551/" target="_blank">Martz & Small, 2019</a>) for a more exclusive clade of ornithischians--basically everyone except <i>Lewisuchus</i>, <i>Soumyasaurus</i>, and <i>Asilisaurus--</i>that have two dental characters and two femur characters, the former related to the onset of herbivory. The name was originally applied to a clade of all silesaurids apart from those three, but silesaurids themselves were, in that paper, still monophyletic. Muller & Garcia (2020) essentially used that definition here, but with traditional Ornithischia included. </p><p>This topology also, as the authors note, results in herbivory arising just twice, in early ornithischians and sauropodomorphs, rather than thrice, when you also include silesaurids as a non-dinosaurian group of dinosauriformes.</p><p>I like this idea--it solves a lot of problems--but will require further testing and more fossils (as always). And where are all the Ansian saurischians?</p>Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-49401368852949347872020-02-06T10:10:00.003-08:002020-02-10T12:30:58.885-08:00Marine Snouters of the Triassic II: Gunakadeit Rising<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6XR-AMhmIBUy20VakW-VMc04UHmEQJ5642yUkiUEI5W44IgqVQNDYh40g0SS_3FqytWHG2csIDbZ4CsOFoMver1ranvRQxBcW0MO-EXpvHOd0VXfw6AlftgDEs0b_J1EemHpEdBZbiTk/s1600/Gunakadeit.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1199" data-original-width="1600" height="239" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6XR-AMhmIBUy20VakW-VMc04UHmEQJ5642yUkiUEI5W44IgqVQNDYh40g0SS_3FqytWHG2csIDbZ4CsOFoMver1ranvRQxBcW0MO-EXpvHOd0VXfw6AlftgDEs0b_J1EemHpEdBZbiTk/s320/Gunakadeit.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Alaska's own <i>Gunakadeit joseeae</i> by the amazing Gabriel Ugueto, or @SerpenIllus on the Twitters.</td></tr>
</tbody></table>
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A very long time ago, I posted an essay about one of my
favorite groups of Triassic marine reptiles: <a href="http://waxing-paleontological.blogspot.com/2017/04/thalattosaurs-doin-things-with-snouts.html">thalattosaurs</a>. These lizard-shaped
swimmers, while generally similar in body form, differ from one another quite
strongly in terms of feeding adaptations. While <i style="mso-bidi-font-style: normal;">Anshunsaurus</i> and <i style="mso-bidi-font-style: normal;">Askeptosaurus</i>
may seem, to our modern eyes, rather vanilla in their clearly faunivorous
dentition, others strain credulity. <i style="mso-bidi-font-style: normal;">Xinpusaurus</i>,
for example, possesses a bizarre notched upper jaw and, in some specimens, an
elongate premaxillary spear which overshoots the the lower jaw by
an impressive degree, calling to mind swordfish and swordfish-snouted
ichthyosaurs. <i style="mso-bidi-font-style: normal;">Thalattosaurus</i> and its
“claraziid” brethren have reduced, shell-crushing dentition and snouts which
curve downward—<i style="mso-bidi-font-style: normal;">Hescheleria</i> takes this
trend to a puzzling extreme. Thalattosaurs also occupied a wide range of body
lengths (1-5 meters). While some were more terrestrially capable than others,
the group never seemed to stray far from the nearshore niche.</div>
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<a name='more'></a><br /></div>
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In that post, I mention that thalattosaurs are found around
the Northern Hemisphere, including one unpublished Alaskan taxon. I was lucky
enough to see this fossil several years ago at the University of Fairbanks’
Museum of the North (many thanks, once again, to Dr. Patrick Druckenmiller for
showing me and my wife around that wonderful place). It’s a beautiful specimen that I have a rather bad picture of on my phone, obscured by my own
reflection on its glass enclosure.<o:p></o:p></div>
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At the time, I thought it looked a bit like <i style="mso-bidi-font-style: normal;">Xinpusaurus</i> or <i style="mso-bidi-font-style: normal;">Endennasaurus</i>, what with the needle-nosed rostrum, but the
dentition was very different. Where <i style="mso-bidi-font-style: normal;">Xinpusaurus</i>
has heterodont dentition of various sizes and shapes, and <i style="mso-bidi-font-style: normal;">Edennasaurus</i> lacks teeth altogether, this unnamed band member had sharp, needle-like teeth to match its needle-nose snout.<o:p></o:p></div>
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I eagerly awaited the little guy’s eventual publication, and
that day came earlier this week.<o:p></o:p></div>
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Say hello to <i style="mso-bidi-font-style: normal;">Gunakadeit
joseeae </i>(<a href="https://www.nature.com/articles/s41598-020-57939-2">Druckenmiller et al. 2020</a>)! <o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja1ZEX4l82Xk9W3r7z5WYIjhe4SW1RB_X6IFP5lqzifOcBbdcQPpNlFwGemxc9bqzETs_ft_bBWfWL18EPMmg6oDwss8XIukYsfbu_X__iwXufr5nnt9PpGJ0r0gw1332oYJvw0aa9tow/s1600/Gunakadeit+%25282020%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="460" data-original-width="1600" height="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja1ZEX4l82Xk9W3r7z5WYIjhe4SW1RB_X6IFP5lqzifOcBbdcQPpNlFwGemxc9bqzETs_ft_bBWfWL18EPMmg6oDwss8XIukYsfbu_X__iwXufr5nnt9PpGJ0r0gw1332oYJvw0aa9tow/s400/Gunakadeit+%25282020%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">UAMES 23258</td></tr>
</tbody></table>
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Continuing the proud tradition of naming Alaska’s prehistoric
fauna after Native Alaskan creatures (<i><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0091287">Nanuqsaurus</a></i>,
<i><a href="https://www.app.pan.pl/article/item/app001522015.html">Ugrunaaluk</a></i>), <i>Gunakadeit</i> (pronounced “Goo-na’-ka-date”) was named after a Tlingit
sea monster who brought good luck to those who saw it. The holotype, UAMES
23258, is nearly complete, lacking only the distal two-thirds of the tail and
the hands. It was found in Southeast Alaska on one of the Keku Islands. It is
of Norian age, so <i>Gunakadeit</i> is one
of the youngest thalattosaurs on record along with Italy’s <i>Endennasaurus</i>.</div>
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<o:p></o:p></div>
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With an estimated length of between 75-90 centimeters, that
puts our boy at just under a yard long, toward the shorter end of the
thalattosaur scale. Among other things, <i style="mso-bidi-font-style: normal;">Gunakadeit</i>
is unique in having an extremely short post-orbital skull region, toothless
anterior snout and needle nose, short neck, and upper temporal fenestrae—which
were lost in other thalattosaurs (due to radically reducing the size of their
squamosal and postorbital bones). The authors revised and added to the character list of <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2016.1218340">Li et al. (2016)</a>, then ran <i style="mso-bidi-font-style: normal;">Gunakadeit</i> through the analysis.
Surprisingly, it’s nowhere near <i style="mso-bidi-font-style: normal;">Endennasaurus</i>
or <i style="mso-bidi-font-style: normal;">Xinpusaurus</i>, instead occupying an
extremely basal position among thalattosaurs generally, but thalattosauroids
specifically, branching off prior to the weird-snouted taxa. This is even stranger
considering it’s one of the only surviving Norian members of the group, which
opens up a 20 million year ghost lineage between it and the earliest known
Ansian thalattosaurs.<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIk592CqaT1km7CIe3NTJpYjmXlZvA1sJfWH9rl4NiaW7DG97vn6qm3Hf5FmbdP-Tz2sJn0sG2wdl0uDRIufZj0co2uWcV4MqihxxDDut243ykcCH98q0IZPKSbmSBKfsF07qahtBGO-4/s1600/Thalattosaur+Tree.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1419" data-original-width="1600" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIk592CqaT1km7CIe3NTJpYjmXlZvA1sJfWH9rl4NiaW7DG97vn6qm3Hf5FmbdP-Tz2sJn0sG2wdl0uDRIufZj0co2uWcV4MqihxxDDut243ykcCH98q0IZPKSbmSBKfsF07qahtBGO-4/s320/Thalattosaur+Tree.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A new phylogeny of thalattosaurs, from Druckenmiller et al. (2020).</td></tr>
</tbody></table>
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The authors suggest that <i>Gunakadeit</i>
went after soft-bodied prey either in open water or by probing in cavities and
crevices with its forceps-like jaws. The little guy’s depositional
environment—a volcanic island surrounded by coral reefs—indirectly supports
this assessment. Aside from the lack of teeth, <i>Edennasaurus</i> differs in one other important way from <i>Gunakadeit</i>: it was probably capable of
walking around on land when the mood struck it. This is probably not the case
with <i>Gunakadeit</i>, who had
poorly-ossified wrists and ankles, flattened forelimb bones, short limbs
generally, and an awkwardly-shaped tail for landlubbing. It's also interesting that the youngest surviving thalattosaurs are superficial similarities in terms of their feeding apparatuses, and may indicate that the
rest of their snouter cousins were outcompeted by other marine animals. And,
indeed, thalattosaurs do not appear to have survived through the Norian.</div>
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Always exciting when a new Mesozoic taxon from Alaska is published, and this is no exception. But also, thalattosaurs are awesome.</div>
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<o:p></o:p></div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com2tag:blogger.com,1999:blog-4675540394850433221.post-46106809823259072652019-05-30T16:09:00.001-07:002019-05-30T16:16:46.493-07:00Walk This Way<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-DmgnzY0fhA2IJ68zVbFrZ5s_S3Xfz1lvMlXdjYuyH7-Fnqyf2fiJDSvfIiZuTEYxCh16wB_I_0Z54c-hNaRdxkkejrXvQi9Fkgsz46LwLKWiYv1Bypqcj0jmMzmEyR6zLesjie0fcys/s1600/Camarasaurus+Hand.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="842" data-original-width="1202" height="224" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-DmgnzY0fhA2IJ68zVbFrZ5s_S3Xfz1lvMlXdjYuyH7-Fnqyf2fiJDSvfIiZuTEYxCh16wB_I_0Z54c-hNaRdxkkejrXvQi9Fkgsz46LwLKWiYv1Bypqcj0jmMzmEyR6zLesjie0fcys/s320/Camarasaurus+Hand.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The right manus of <i>Camarasaurus</i>. Note the columnar arrangement and virtual absence of fingers.</td></tr>
</tbody></table>
Late last year, I introduced you all to the <a href="http://waxing-paleontological.blogspot.com/2018/10/they-might-be-giants.html">Lessemsauridae</a>,
a group of near-sauropod "prosauropods" that grew unreasonably large—up to 12 tons
in <i>Ledumahadi mafube</i>. There’s some
disagreement about the posture of these enormous animals: in true, blue
Sauropoda, the forelimbs are columnar, the hands are pronated, the weight is
bore on the fingertips, and there is a reduction in phalanges and claws. This
arrangement is present to some degree even in the earliest true sauropods like <i>Melanorosaurus</i> and <i>Barapasaurus</i>.<br />
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<a name='more'></a><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiVgRo0D29MLmeifURBEEaSpVHVmEya04EFzilpqBqnsBE1aUfDI7nzr_P_xrK8Kdrl29TvyVX0Lt57ZVkiguxF96yY93opPptfYpBIG2jHoCzM9RjECkI97t796n5HinI_peV0xWNhE0/s1600/Plateosaurus+hand.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="414" data-original-width="640" height="207" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiVgRo0D29MLmeifURBEEaSpVHVmEya04EFzilpqBqnsBE1aUfDI7nzr_P_xrK8Kdrl29TvyVX0Lt57ZVkiguxF96yY93opPptfYpBIG2jHoCzM9RjECkI97t796n5HinI_peV0xWNhE0/s320/Plateosaurus+hand.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The right hand of <i>Plateosaurus</i>. Note the long digits II & III and surprisingly large claws.</td></tr>
</tbody></table>
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By contrast, prosauropods have forelimbs that could
not pronate, and their hands are a bit more theropod-like, with elongate digits
I-III followed by much shorter, vestigial digits IV & V. The thumb (digit
I) is interesting in that the first phalange articulates to its metacarpal at
an angle—a “twist” that seems to be the standard configuration in prosauropods
going back even as far as <i>Eoraptor</i>.
Also popular among prosauropods is an extremely large, recurved thumb-claw. If
you go by their hand morphology, it’s clear that prosauropods were still
actively using their forelimbs for non-weight-bearing activities. What kind of hands did lessemsaurids have? Unfortunately, that remains a mystery.</div>
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<o:p></o:p></div>
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But wait, you say, if normal prosauropods weren’t walking around on
their hands that must mean they were bipedal…?<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTNdVeNqaSa03_rbh-bjKp-OQrf5hvGuuNJCgZNb8Ky3mhTpax8DNtghu3W1r1P_jeTM8Y7bx6LJXWq7zvVU5mOJJdCRWded64eJDzJrqO2JlsVdDlKaYKs54_dk6HYF5CNpzTbX5KAEA/s1600/Plateosaurus+Digital+Skeleton+%25282010%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1398" data-original-width="1600" height="279" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTNdVeNqaSa03_rbh-bjKp-OQrf5hvGuuNJCgZNb8Ky3mhTpax8DNtghu3W1r1P_jeTM8Y7bx6LJXWq7zvVU5mOJJdCRWded64eJDzJrqO2JlsVdDlKaYKs54_dk6HYF5CNpzTbX5KAEA/s320/Plateosaurus+Digital+Skeleton+%25282010%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Plateosaurus</i> was a perfectly capable biped, from Mallison (2010a).</td></tr>
</tbody></table>
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I know, this is a concept I’m still trying to wrap my head
around, even though <a href="https://www.researchgate.net/publication/272152840_Were_the_basal_sauropodomorph_dinosaurs_Plateosaurus_and_Massospondylus_habitual_quadrupeds">Bonnan & Senter (2007)</a> and then Mallison (<a href="https://palaeo-electronica.org/2010_2/198/index.html">2010a</a>; <a href="https://www.app.pan.pl/article/item/app20090075.html">2010b</a>)
deemed these big herbivores incapable of quadrupedality. Certainly my ingrained
mental image of any given prosauropod is basically a mini-sauropod with all
four extremities used for walking around, palms flat on the ground. Turns out that would’ve been more or
less impossible for somebody like <i>Plateosaurus</i>:
the wrist was inflexible, the arm couldn’t pronate, only digits II & III
would’ve reached the ground anyway, and the limb proportions would’ve led to some <i>interesting</i> compromises as a quadruped.
Thus, I’ve had to say goodbye to that classic prosauropod posture, but old
habits die hard, and I have a weirdly difficult time seeing them as bipeds.</div>
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(I have a <i style="mso-bidi-font-style: normal;">more</i>
difficult time understanding how those pot-bellied therizinosaurs got around on two legs, but
that’s a topic for another day.)<o:p></o:p></div>
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But somewhere along the line—well, specifically around the
origin of Sauropoda—they must have figured out how to walk on all fours.
Surprisingly, it’s looking like they did this through paedomorphosis—that is,
the retention of juvenile characteristics. <o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbtewo5_6317kU6b9jV5mOT9Xj_NtX7_D2etG_wxXTlJHdmFrcLngcw19vdm0aAk6Rit-Y7rdvV5TNQoU_jX0v8KcbPw2d5BFSkghp_7BkI4fk3OhN0nVs8qeSlg63FqjV9baVpkikkCk/s1600/Massospondylus+Hatchling.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="843" data-original-width="710" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbtewo5_6317kU6b9jV5mOT9Xj_NtX7_D2etG_wxXTlJHdmFrcLngcw19vdm0aAk6Rit-Y7rdvV5TNQoU_jX0v8KcbPw2d5BFSkghp_7BkI4fk3OhN0nVs8qeSlg63FqjV9baVpkikkCk/s320/Massospondylus+Hatchling.jpg" width="268" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">It's so cute!</td></tr>
</tbody></table>
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In 2005, <a href="https://www.researchgate.net/publication/7693610_Embryos_of_an_Early_Jurassic_Prosauropod_Dinosaur_and_Their_Evolutionary_Significance">Reisz et al.</a> published on gorgeous, articulated,
near-term embryos referable to poster-child prosauropod <i>Massospondylus carinatus</i>. As an adult, <i>Massospondylus</i> was—like its cousin <i>Plateosaurus</i>—an obligate biped. The hatchlings, however, must have
been obligate quadrupeds: they have a proportionately enormous skull,
horizontally-held neck seemingly incapable of a proper S-curve, proportionately
long forelimbs, and weak hind limbs. The baby’s center of mass would have been
too far forward for a bipedal posture anyhow—attempting to walk on its hind
legs would have caused it to, tragically but I have to assume hilariously, topple forward.</div>
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<o:p></o:p></div>
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<br /></div>
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Reisz et al. (2005) also suggest that, due to the large
head, weak limbs, and nearly complete absence of teeth in these hatchlings,
that <i>Massospondylus</i> babies were
altricial and had to be cared for by adults for some amount of time after
hatching. </div>
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<br /></div>
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This idea is reinforced when Reisz et al. revisited the embryos in
<a href="https://www.academia.edu/14920456/Embryonic_skeletal_anatomy_of_the_sauropodomorph_dinosaur_Massospondylus_from_the_Lower_Jurassic_of_South_Africa">2010</a>, noting that in near-term hatchlings of later sauropods and hadrosaurs
already have teeth. Notably, proper sauropod hatchlings are assumed to have
been precocial in the manner of sea turtles—digging their way out of the nest
after hatching and able to survive on their own. Well, you know, those that survived the immediate population bottleneck created by every available carnivore on Hatching Day.* One wonders if altriciality in
<i>Massospondylus</i> was derived or
represents the basal condition for Sauropodomorpha as a whole.</div>
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<o:p></o:p></div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBe8zndmVLI25r9lz-rTckG19e67jvAm4uOxM7sZZrQ3vnbi7WgIIHdUKzNUcPk2tDNVnfpoP4zO600jpVX_98KeRx3HKN8jGmRQBc2IBnJe79fGCMWZggYrNcJj91a34yiXiFhE-HLS8/s1600/Massospondylus+Hatchling+2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="608" data-original-width="1600" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBe8zndmVLI25r9lz-rTckG19e67jvAm4uOxM7sZZrQ3vnbi7WgIIHdUKzNUcPk2tDNVnfpoP4zO600jpVX_98KeRx3HKN8jGmRQBc2IBnJe79fGCMWZggYrNcJj91a34yiXiFhE-HLS8/s320/Massospondylus+Hatchling+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Restoration of a <i>Massospondylus</i> hatchling from Reisz et al. (2010)</td></tr>
</tbody></table>
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At some point during their lives, though, the juvenile <i>Massospondylus</i> would have developed
stronger hind limbs, less-forgiving forelimbs, and switched to a bipedal
posture. But how old were the animals when this shift occurred?</div>
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<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZk0fL2b3bWsuvy5oF08lktEdEex04g7QSPe6zhu_ceCsW1BszJuTmLnVA8mxP4VAhu37iLcnvFs6-e0lscsnrEOjUhOvq26lrtTejg0Lhj_lMl7HXVy1YnfjvsLUeqqfL9G46cUxVXK4/s1600/Mussaurus.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="982" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZk0fL2b3bWsuvy5oF08lktEdEex04g7QSPe6zhu_ceCsW1BszJuTmLnVA8mxP4VAhu37iLcnvFs6-e0lscsnrEOjUhOvq26lrtTejg0Lhj_lMl7HXVy1YnfjvsLUeqqfL9G46cUxVXK4/s320/Mussaurus.jpg" width="196" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Mussaurus </i>growth series from Otero et al. (2019)</td></tr>
</tbody></table>
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A close relative has provided the answer: very young. <a href="https://www.nature.com/articles/s41598-019-44037-1">Otero et al. (2019)</a>
just published a paper that specifically addresses this question in <i style="mso-bidi-font-style: normal;">Mussaurus
patagonicus</i>. The authors studied a group of hatchlings, a yearling, and an
adult. Brief aside: the hatchlings were closely associated and found with eggs
and eggshells, suggesting they stayed together in the nest. Their joint
surfaces are also poorly ossified, which may be more evidence for post-hatching
parental care in prosauropods. Anyway, Otero et al. (2019) note that, in one of
the hatchling skeletons, the position of the radius and ulna indicate “at
least, a semi-pronation of the forelimb.” By the time <i style="mso-bidi-font-style: normal;">Mussaurus</i> celebrated its first birthday, however, the center of
mass had shifted caudally enough that it could assume a bipedal posture, and
the forelimbs begin to take on their adult proportions. At the very least,
yearlings were facultative bipeds. </div>
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<br /></div>
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<br /></div>
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<br /></div>
<div class="MsoNormal">
The biggest reason for this center of mass
shift is the development of a long, muscular tail which, in turn, supported a
growing <i>M. caudofemoralis</i> muscle
anchored to a large fourth trochanter, allowed the hindlimbs to take over. The
semi-pronated forelimb of the hatchlings is intriguing, though, and suggests
that true sauropods evolved their columnar, pronated forelimbs via retention of
juvenile (in this case, hatchling) characters.</div>
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<o:p></o:p></div>
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<br /></div>
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It’s funny to think, then, that the largest land animals to ever exist might really be oversized babies.<o:p></o:p></div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNtZ3CHUD1o__v_nm-AvJ3cF1b7d4Yhi45XkePoe0nwHEFYgkM8tm5x9BG5m3vbUtkuqwNWTpF-N92pSfUEkx61f2W6Z3a4qjALUIc7CcSFhdtkcnRcbX-0EXxmIvN4pH-6eS09S9s0ZM/s1600/Dreadnoughtus.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="800" data-original-width="1200" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNtZ3CHUD1o__v_nm-AvJ3cF1b7d4Yhi45XkePoe0nwHEFYgkM8tm5x9BG5m3vbUtkuqwNWTpF-N92pSfUEkx61f2W6Z3a4qjALUIc7CcSFhdtkcnRcbX-0EXxmIvN4pH-6eS09S9s0ZM/s400/Dreadnoughtus.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Dreadnoughtus</i>, a giant baby, by the incomparable <a href="http://markwitton-com.blogspot.com/2014/09/hey-dreadnoughtus-not-so-close.html">Mark Witton</a>.</td></tr>
</tbody></table>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com0tag:blogger.com,1999:blog-4675540394850433221.post-2790360151612188792019-05-02T12:23:00.002-07:002019-05-02T12:23:23.357-07:00Don't knock my Smok or I'll clean your clock!<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9B56-MOqJ7_LgUO1zzw0bTIiK2EciD8Q8Y3NEa5wvUbjTcnyETlMaDGW4WHjD4r6xkq2dVd-YiQUM5ZCHmUVzriOlcxqXCGnFvz9UmWNC_pW5EI2Au8_YmIF1sD7ODbBYdnoLqtICIUY/s1600/Smock.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="518" data-original-width="805" height="205" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9B56-MOqJ7_LgUO1zzw0bTIiK2EciD8Q8Y3NEa5wvUbjTcnyETlMaDGW4WHjD4r6xkq2dVd-YiQUM5ZCHmUVzriOlcxqXCGnFvz9UmWNC_pW5EI2Au8_YmIF1sD7ODbBYdnoLqtICIUY/s320/Smock.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">We miss you, Bill Watterson.</td></tr>
</tbody></table>
A few months ago, I wrote that my favorite paleo story of
2018 was the publication of <i>Lisowicia
bojani</i>, a ridiculously large dicynodont from Poland. In that same post, I
mentioned <i>Smok wawelski</i>, a
similarly-sized predatory archosaur of uncertain phylogenetic affinities that
very likely hunted <i>Lisowicia</i>. It
strikes me that <i>Smok</i> might be
unfamiliar to many of you out there in Readerland, so today’s quick post is a
summary of what we know about this mysterious carnivore. By the way, I posted this <i>Calvin & Hobbes</i> strip because every time I hear the name <i>Smok</i> I immediately think of it.<br />
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<o:p></o:p></div>
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</div>
<a name='more'></a>The animals that would eventually be named <i style="mso-bidi-font-style: normal;">Smok</i> and <i style="mso-bidi-font-style: normal;">Lisowicia</i> were first reported by <a href="https://www.app.pan.pl/article/item/app53-733.html">Dzik (2008)</a>, who thought that the
former was a theropod dinosaur—not an unreasonable assumption. He did not,
however, name either animal. That would come four years later (<a href="https://www.app.pan.pl/article/item/app20100045.html">Niedzwiedzki,Sulej, & Dzik, 2012</a>), although not without a footnote. A good amount of
material was recovered: a braincase, skull bones, pelvic and limb bones, a few
vertebrae, and a couple partial ribs. The premaxilla, maxilla, and jugal bones
indicate a deep skull. The pubis is directed downward and apparently has a large
posteriorly-directed boot, which reminds me of <i style="mso-bidi-font-style: normal;">Herrerasaurus</i> but the details are very different. The whole animal
is estimated to be between 16-20 feet long.<br />
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<o:p></o:p></div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaCMfhisJ-iXWQu5ouTGRy0eaQeFKR72slgx3smkccNqMg4ZHFNcBSfTAyKi8DzsgiNsm3ixvmy7UTKnqP4J6I9elyiH8Z6YDnO5VSWKbg9UBdI7SNjiDtgmFtsvc7OqSfh4VH2zIu0RI/s1600/Smok.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="690" data-original-width="1600" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaCMfhisJ-iXWQu5ouTGRy0eaQeFKR72slgx3smkccNqMg4ZHFNcBSfTAyKi8DzsgiNsm3ixvmy7UTKnqP4J6I9elyiH8Z6YDnO5VSWKbg9UBdI7SNjiDtgmFtsvc7OqSfh4VH2zIu0RI/s400/Smok.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Smok wawelsi, </i>who might not look like this.</td></tr>
</tbody></table>
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A phylogenetic assessment was outside the scope of
Niedzwiedzki et al. (2012), as it is the subject of Niedzwiedzki’s PhD
thesis. The authors don’t go too much farther than placing <i>Smok</i> in Archosauria, as it shares features in common with theropods and rauisuchians—two groups that
converged a great deal during the Late Triassic. Additionally, it presents a
few more plesiomorphic (primitive) features that you wouldn’t expect in either a theropod
or rauisuchian. Interestingly, <i>Smok</i>
shared its environment with with three prominent rauisuchians: <i>Batrachotomus, Polonosuchus, </i>and <i>Teratosaurus</i>. I guess we’ll continue to
wait for a full description and/or phylogenetic analysis.</div>
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<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOkrh41Y0tb_8pR1rQhhEFoQB4VLiIQa7yNq4eR-WeZHAT7S_5FQHJNRbtL1a07ZbNunog5K4rF9I7iXqzljgU6P8-G8zxsZbZeJ4FUczmOvT_lsOJTLemGubzXRl41kZLvSt2Vh6DWX0/s1600/Smok+Femur.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="578" data-original-width="526" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOkrh41Y0tb_8pR1rQhhEFoQB4VLiIQa7yNq4eR-WeZHAT7S_5FQHJNRbtL1a07ZbNunog5K4rF9I7iXqzljgU6P8-G8zxsZbZeJ4FUczmOvT_lsOJTLemGubzXRl41kZLvSt2Vh6DWX0/s320/Smok+Femur.jpg" width="289" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Femur bones of <i>Smok</i>, <i>Lilensternus</i>, and <i>Postosuchus</i></td></tr>
</tbody></table>
A second specimen of <i style="mso-bidi-font-style: normal;">Smok</i>
was briefly described in 2018 by <a href="http://www.app.pan.pl/article/item/app005052018.html">Niedzwiedzki & Budziszewska-Karwowska</a>
which may represent a second species. There’s not much to describe—two isolated
teeth, a dorsal vertebra, fragments of a humerus, femur, pubic boot, and
ischial shaft. The vertebra differ a bit from those in the holotype, and the authors entertain the idea of a second species but without more
material that’s impossible to determine. The paper also notes that <i style="mso-bidi-font-style: normal;">Smok</i>’s full description is ongoing.</div>
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<o:p></o:p></div>
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<br /></div>
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<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
And then, this last January, <a href="https://www.nature.com/articles/s41598-018-37540-4">Qvarnstrom, Ahlberg, &Niedzwiedzki (2019)</a> published a paper discussing osteophagy in <i style="mso-bidi-font-style: normal;">Smok</i> based on several coprolites
associated with body fossils and footprints assigned to that genus. The authors write:<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal" style="margin-left: .5in;">
The material of <i style="mso-bidi-font-style: normal;">S. wawelski </i>is associated with<i style="mso-bidi-font-style: normal;"> </i>numerous bones of a large dicynodont as
well as other vertebrates. Many of these bones show deep bite marks; one
juvenile dicynodont fibula has had its distal head bitten off. The size of the
bite marks matches the teeth of <i style="mso-bidi-font-style: normal;">S.
wawelski</i>, which suggests that this predator was at least an occasional
osteophage.<o:p></o:p></div>
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<br /></div>
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Analysis of the associated coprolites indicates that animals
of all ages, growth rates, and both terrestrial and aquatic were all preyed on
by <i style="mso-bidi-font-style: normal;">Smok</i>. Some of the teeth match the
size and shape of <i style="mso-bidi-font-style: normal;">Smok</i> itself,
suggesting that it either swallowed its own broken crowns (not unreasonable) or
that this predator was not above cannibalism. In addition to coprolites and bone-rich
regurgitalites (basically fossil vomit) containing larger pieces of bone mean
that <i style="mso-bidi-font-style: normal;">Smok</i> threw up larger,
indigestible fragments as predatory birds do today.<o:p></o:p><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiisNviLt_UyduJMWhtPXyE4MXeByQdQHkd9KWCXsST1zPzUmpPgRVj4XHT955ckDpAvn93SoTYsrkOUyL3E26jmm40Qv8DYWWxhKbg4rWJeYed5C8ubQv7ybwz40-MEdr8wh4cqNMopuU/s1600/Smok+Osteophagy.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="996" data-original-width="1226" height="259" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiisNviLt_UyduJMWhtPXyE4MXeByQdQHkd9KWCXsST1zPzUmpPgRVj4XHT955ckDpAvn93SoTYsrkOUyL3E26jmm40Qv8DYWWxhKbg4rWJeYed5C8ubQv7ybwz40-MEdr8wh4cqNMopuU/s320/Smok+Osteophagy.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Three <i>Smok</i> coprolites, packed to the gills with bone fragments</td></tr>
</tbody></table>
Osteophagy is rare in reptiles and, in fact, the authors
note that <i style="mso-bidi-font-style: normal;">Tyrannosaurus rex</i>, of all
archosaurs, provides a comparable model for the kind of large-scale osteophagy
that <i style="mso-bidi-font-style: normal;">Smok</i> exhibits:</div>
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<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="margin-left: .5in;">
The coprolites of <i style="mso-bidi-font-style: normal;">S. wawelski</i> contain at least as much
bone per volume as <i style="mso-bidi-font-style: normal;">T. rex</i>, and the
size fractions of bones and the degree of etching are very similar. Even though
<i style="mso-bidi-font-style: normal;">S. wawelski</i> is considerably smaller
than these tyrannosaurs, we conclude that it occupied a similar ecological role
of osteophagous top predator.<o:p></o:p></div>
<div class="MsoNormal" style="margin-left: .5in;">
<br /></div>
<div class="MsoNormal">
So we might not know exactly what kind of archosaur <i style="mso-bidi-font-style: normal;">Smok</i> was, but we do know that it was
very large, it ate pretty much everything it came into contact with. The jury's still out on what kind of archosaur it was, exactly, but I'm sure we'll find out before too long. My money's on a theropod identity since there are already a bunch of rauisuchians in the same area. </div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-69949229248145257472019-01-25T19:00:00.001-08:002019-01-25T19:00:06.133-08:00Whale-Lizards of the Triassic III: Revenge of Eretmorhipis<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje5wZcRiBUdh4ep0O2dv8kmT7tzYBAiIMR-NU1PO_BPRqFkafW9UFhgIONlfcgp23IcA6WyxZpu7-BCy6CEgxC29_tVY2OaX4REFNzs7_T5XX7k2Mulycc5kmDoOizyhaNPjL6VZzbhrY/s1600/Eretmorhipis.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="341" data-original-width="1600" height="68" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje5wZcRiBUdh4ep0O2dv8kmT7tzYBAiIMR-NU1PO_BPRqFkafW9UFhgIONlfcgp23IcA6WyxZpu7-BCy6CEgxC29_tVY2OaX4REFNzs7_T5XX7k2Mulycc5kmDoOizyhaNPjL6VZzbhrY/s320/Eretmorhipis.jpg" width="320" /></a></div>
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You might fondly remember the two previous posts in this series: <a href="http://waxing-paleontological.blogspot.com/2015/03/hupehsuchians-primer.html">Part I</a> and <a href="http://waxing-paleontological.blogspot.com/2016/07/hupehsuchians-2-return.html">Part II</a> which describe a particularly bizarre group of basal ichthyosauromorphs called hupehsuchians. Known for their "bony body tubes" and wide, toothless mouths, hupehsuchians are a surprisingly diverse group that includes five monospecific genera: <i><a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0102361">Nanchangosaurus</a></i>, <i><a href="http://rstb.royalsocietypublishing.org/content/331/1260/131">Hupehsuchus</a></i>, <i><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0115244">Eohupehsuchus</a></i>, <i><a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0094396">Parahupehsuchus</a></i>, and <i><a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0126024">Eretmorhipis</a></i>. <i>Eretmorhipis</i> is the most recently-described hupehsuchian (Chen et al. 2015) but also one of the more mysterious, as the holotype does not include a skull or even cervicals. I should mention this is also the case with <i>Parahupehsuchus</i> although it's missing most of the tail, too.<br />
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Based on hupehsuchians with skulls (<i>Hupehsuchus, Nanchangosaurus,</i> and <i>Parahupehsuchus</i>), the general feeling has been that these marine reptiles were lunge-feeders in the style of pelicans and baleen whales. <a href="https://www.nature.com/articles/srep08900">Motani et al. (2015)</a> have summarized this quite well and even speculate that <i>Hupehsuchus</i>, at least, may have had soft-tissue structures for filter-feeding along the premaxillae.<br />
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But then we come to <i>Eretmorhipis</i>. New complete specimens described this week (<a href="https://www.nature.com/articles/s41598-018-37754-6">Cheng et al. 2019</a>) demonstrate that hupehsuchians, as a group, were far more ecologically diverse than we thought.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv_NjTQTkfqD8mGLmYBYeKY4y2Lp9KqNrCpjzpfolfqQFgwExusXNDs-UeXBizOZc1AjhRvwr1R-rwv9B2t_2_dmKn66b9nybtKbtKHhuHd40_boPZa554SNm-n6Sw1JW16kGLk7xjnqE/s1600/Eretmorhipis+Skeleton.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="436" data-original-width="685" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv_NjTQTkfqD8mGLmYBYeKY4y2Lp9KqNrCpjzpfolfqQFgwExusXNDs-UeXBizOZc1AjhRvwr1R-rwv9B2t_2_dmKn66b9nybtKbtKHhuHd40_boPZa554SNm-n6Sw1JW16kGLk7xjnqE/s400/Eretmorhipis+Skeleton.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Listen, guys, I don't even have words for how strange this is.</td></tr>
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<i>Eretmorhipis</i> was clearly not splitting the atom. That is a very tiny head, folks. I do question whether that skeletal accurately portrays the size of the forelimbs. For comparison, here's the holotype:</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPXFPzd4Bx6GFRIeEm8nsnuwvgw2BElZWDbAcP6JFKqPVte2GfbRFEmuC0Y9QoLv9zZpqB1KJIjXSiTzBtW_e0f7F2an6wSwXIF4ZQgUyPBJt7JfHrvraXcYOfneyoC9hjydkS0XAtXIQ/s1600/Eretmorhipis+Holotype.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="499" data-original-width="1600" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPXFPzd4Bx6GFRIeEm8nsnuwvgw2BElZWDbAcP6JFKqPVte2GfbRFEmuC0Y9QoLv9zZpqB1KJIjXSiTzBtW_e0f7F2an6wSwXIF4ZQgUyPBJt7JfHrvraXcYOfneyoC9hjydkS0XAtXIQ/s640/Eretmorhipis+Holotype.png" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Note that the holotype does not preserve those dorsal plates, either.</td></tr>
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Forelimbs larger than hindlimbs, sure, but Wreck-It Ralph big? I dunno.<br />
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Other things you may notice about <i>Eretmorhipis</i>: the small dermal armor ossicles (?) that cap the top of the dorsal vertebrae in every other hupehsuchian has grown to enormous size. The authors compare them to the conspicuous dorsal plates of <i>Stegosaurus</i>, and I can't think of a better analogue. There are ten such structures arranged in a line from the back of the neck to the base of the tail. While this may be a logical extension of the minimal dorsal armor of its relatives, these "plates" are still surprising, especially in a marine animal you'd want to be hydrodynamic.<br />
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But let's go back to that almost tragically tiny head. In profile, it looks sort of like a toothless crocodile skull without room for eyes or nostrils. In dorsal view, it looks like somebody put a pair of tweezers where the nose should be (the same can be said for the mandible). In fact, as the authors write, the skull looks a lot like that of <i>Ornithorhynchus anatinus</i>--the duck-billed platypus.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggSnsVVLQn6Ovis0Gm126EuKfBwhiSFYUmT08oWdAk1qyl0E3gQmjhmVeqfxe2Xbq_ENSC_bvudJaKWbBdV3o5tLIUCyzJIjZbIezbxl2usArIrdUNnyh10UrSjPgKuDFnJKeHBQ1wVrQ/s1600/Eretmorhipis+Skull+Comparison.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="901" data-original-width="718" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggSnsVVLQn6Ovis0Gm126EuKfBwhiSFYUmT08oWdAk1qyl0E3gQmjhmVeqfxe2Xbq_ENSC_bvudJaKWbBdV3o5tLIUCyzJIjZbIezbxl2usArIrdUNnyh10UrSjPgKuDFnJKeHBQ1wVrQ/s320/Eretmorhipis+Skull+Comparison.jpg" width="255" /></a></div>
Here are the two side-by-side: platypus on the left and <i>Eretmorhipis</i> on the right. The blue space represents labial cartilage which makes up the soft-tissue "beak" in platypuses and is inferred for <i>Eretmorhipis</i>. The platypus has a pair of foramen, one in front of each eye, for the ethmoidal nerve which provides sensory branches to the nasal cavity. <i>Eretmorhipis</i> appears to have analogous foramen, which are extremely rare in reptiles and unknown in other hupehsuchians. Besides gross differences in form, however, the two are quite different. The external nares of <i>Ornithorhychus</i> are way down at the end of the snout whereas they are about halfway up the skull in <i>Eretmorhipis</i>. The mandible of <i>Eretmorhipis</i> was also seemingly frozen in a mirror image of the snout, un-fused symphysis included, and was probably not capable of bowing to the extent hypothesized for <i>Hupehsuchus</i>.<br />
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But it's the size of the eyes that the authors are most impressed by: <i>Eretmorhipis</i> has mere vestiges of eyes, seemingly useless in terms of resolution. <i>Eretmorhipis</i> was about the size of <i>Hupehsuchus</i> but had eyes half as large. This, in addition to the inferred snout structure, implies that <i>Eretmorhipis</i> was not using sight as its primary sense, but touch. Although exceedingly rare in amniotes, it's possible that <i>Eretmorhipis</i> had electroreceptors in addition to its enhanced tactile snout.<br />
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The "bony body tube" is also present in <i>Eretmorhipis</i>, and Chen et al. (2019) note that the tail must not have been all that flexible either given that the hemal spines span three caudals apiece and are almost horizontally-oriented. Given the rigidity of its axial skeleton, <i>Eretmorhipis</i> must have relied heavily on its giant paddle-shaped limbs to get around.<br />
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Seemingly the entire clade is restricted to an enormous lagoon spanning about 1200 kilometers (745ish miles) east to west and 500 kilometers and 500 kilometers (310ish miles) north to south and they all lived together at the same time. Now that's a lot of lagoon to go around, but one does wonder how multiple species of hupehsuchian (and more are coming) avoided direct competition with each other. <i>Eretmorhipis</i> accomplished this by going blind and grabbing prey that could be sensed by touch alone.<br />
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I'm sure this isn't the last entry in this multi-part series and I look forward to whatever curveballs this group throws our way in the future.Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com2tag:blogger.com,1999:blog-4675540394850433221.post-25713748282775639602019-01-08T13:00:00.003-08:002019-01-08T15:01:39.477-08:00Big Finish to 2018<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIxpOJTu24I9RZxDa5lRmWoZjNvhDDkOpUK4B1eepTvleE0sx7qgeYrkoZQSAuIcP4RHUcUpkXTGmXe-d8zGpdGkT22lj11dyidVs67RAQg5sTsyfuRzSgr0uEhkl82l_Rd-Txiy2dR_8/s1600/Crittendenceratops.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1056" data-original-width="1574" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIxpOJTu24I9RZxDa5lRmWoZjNvhDDkOpUK4B1eepTvleE0sx7qgeYrkoZQSAuIcP4RHUcUpkXTGmXe-d8zGpdGkT22lj11dyidVs67RAQg5sTsyfuRzSgr0uEhkl82l_Rd-Txiy2dR_8/s320/Crittendenceratops.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Despite Sergey Krasovskiy's gorgeous art, it is not <i>Crittendenceratops</i>.</td></tr>
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First of all, sorry for not writing anything in December. We
spent half the month on vacation and the other half madly trying to finish
things before the vacation and playing catch-up after the vacation. It was
a good vacation; we went to Kauai. I don’t know if you’ve ever been to Kauai
but it’s the complete opposite of Alaska, especially during December. I did
some writing while on vacation but nothing serious and besides I didn’t have
any of my reference material on-hand. However, I did work on a longer-term project that's been on my mind for awhile now. Details as they emerge.<br />
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For this short post, the first of the new
year, I want to talk about my favorite paleo news story of 2018.</div>
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Surprisingly, it’s not a dinosaur. My favorite
groups—ceratopsians and theropods—didn’t get a lot of love in 2018. <i style="mso-bidi-font-style: normal;"><a href="https://www.nature.com/articles/s41467-017-02515-y">Caihong</a></i> was an early surprise and those
<a href="https://www.cell.com/current-biology/fulltext/S0960-9822(18)30987-4?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982218309874%3Fshowall%3Dtrue">two alvarezsaurids</a> were also nice, but <i style="mso-bidi-font-style: normal;"><a href="https://www.researchgate.net/publication/328637301_A_NEW_CERATOPSID_DINOSAUR_CENTROSAURINAE_NASUTOCERATOPSINI_FROM_THE_FORT_CRITTENDEN_FORMATION_UPPER_CRETACEOUS_CAMPANIAN_OF_ARIZONA">Crittendenceratops</a></i>
is hardly worth mentioning despite its unusually lengthy description and
extremely speculative skeletal and life restoration given the material
described. If I had to pick a favorite dinosaur story, it would be the
recognition and erection of the <a href="https://waxing-paleontological.blogspot.com/2018/10/they-might-be-giants.html">Lessemsauridae</a>, a group of very large
“prosauropods” who were larger than the earliest true sauropods but lacked many
of the skeletal features everyone assumed were necessary for gigantism (like
columnar legs).<o:p></o:p></div>
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Oh, and another early surprise was the <a href="https://academic.oup.com/zoolinnean/article-abstract/184/4/1187/4996397">osteology of <i style="mso-bidi-font-style: normal;">Buriolestes</i></a>, a sauropodomorph so basal it was still carnivorous. <o:p></o:p></div>
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But none of these were my favorite paleo news story of 2018. No, the top spot goes to a story that’s actually similar to the Lessemsauridae story in that the animal in
question is an unexpectedly gigantic member a group previously comprised of
small to modestly large taxa: <i style="mso-bidi-font-style: normal;"><a href="http://science.sciencemag.org/content/363/6422/78">Lisowicia bojani</a></i>.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi14xPvE8zU90Sw22tA_bKWMPyh2AOEMttE3hHXixpHxT0wU8mL-7IwUT2bLfFt3GEeFP6PWlJV2tOP1roW7tcuapCw2nxPX-3yNG8Dd1VBvaEBoMIBq3INNWMiQz0gy4A5yPnOSTLNEto/s1600/Lisowicia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="736" data-original-width="578" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi14xPvE8zU90Sw22tA_bKWMPyh2AOEMttE3hHXixpHxT0wU8mL-7IwUT2bLfFt3GEeFP6PWlJV2tOP1roW7tcuapCw2nxPX-3yNG8Dd1VBvaEBoMIBq3INNWMiQz0gy4A5yPnOSTLNEto/s320/Lisowicia.jpg" width="251" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Jaw-dropping illustration by Julius Csotonyi</td></tr>
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An enormous “prosauropod” is surprising but not wholly out
of left field. An elephant-sized dicynodont is out of an entirely different
ballpark. Now, granted, I’m not an expert on dicynodonts, but the previous
record-holders were <i>Placerias,
Stahleckeria</i> and <i>Ischigualastia</i>—about
the length and weight of modern cattle but shorter and bulkier. Dicynodonts
famously had a “hybrid” stance: erect hindlimbs with semi-sprawling forelimbs.
Dicynodonts were arguably the most successful herbivores of during the
Triassic: having already weathered the Great Dying, they came out the other
side in a more dominant and competition-free ecological position.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiG0lgXonGDsWAadj4Y92FIjoqbxfbNztUhWEX7JR1wcpms6BRss_qv5MueYoCQztKKBGiboTE9U_98MlS7PhhgpWpHYKTo5Zt53qYk2DlUDaWtBwjjd7FeBPx8i3Tk7gejosJXPEQswWg/s1600/Lisowicia+Skeletal.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="969" data-original-width="1433" height="216" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiG0lgXonGDsWAadj4Y92FIjoqbxfbNztUhWEX7JR1wcpms6BRss_qv5MueYoCQztKKBGiboTE9U_98MlS7PhhgpWpHYKTo5Zt53qYk2DlUDaWtBwjjd7FeBPx8i3Tk7gejosJXPEQswWg/s320/Lisowicia+Skeletal.jpg" width="320" /></a></div>
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Cow-sized dicynodonts are fine and dandy, but <i>Lisowicia</i> tipped the scales at around <i>nine tons</i> which is more than an average
adult African elephant (6.5 – 7 tons). It was more than 4.5 meters (14.75 ft)
long and 2.6 meters (8.5 ft) tall. To accommodate such enormity, <i>Lisowicia</i> had erect forelimbs. It lived
in Poland alongside basal dinosauriform <i>Silesaurus</i>
and <i><a href="https://www.app.pan.pl/article/item/app20100045.html">Smok</a></i>, an enormous predatory
archosaur (5 -6 meters; 16 – 20 ft) of uncertain phylogenetic affinity that
was almost certainly capable of going after even the elephant-sized <i>Lisowicia</i> and I wonder if the latter
lived in groups to help avoid such confrontations (turns out the two <a href="https://www.app.pan.pl/article/item/app005052018.html">may have been neighbors</a> after all).</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4YkJRncrNGJGoxCS5f-9ndgNT0BJDKUsIGgi2gJyVVOUVjAp6Rko-aw9abcb9zJFUoSsc_bB_642Xfl0EdQAGvkq0rmIsIPWvY1B-kyyhcayUXHbmnOzawzbx1Eu9uybvY8DuSInzkeA/s1600/Smok.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="551" data-original-width="1280" height="137" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4YkJRncrNGJGoxCS5f-9ndgNT0BJDKUsIGgi2gJyVVOUVjAp6Rko-aw9abcb9zJFUoSsc_bB_642Xfl0EdQAGvkq0rmIsIPWvY1B-kyyhcayUXHbmnOzawzbx1Eu9uybvY8DuSInzkeA/s320/Smok.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">In case you were unaware of <i>Smok wawelski</i></td></tr>
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There's still plenty left in the Triassic to surprise us!</div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-84609743155699435042018-11-16T13:19:00.002-08:002018-11-16T13:19:29.939-08:00Thanos Deserves Better<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfbCwK5E5WpNmhsjpQJHHTR6oVg5h2i1hv4qqppQAH1fZP2J28UeGvtrLq7bMEItqeiYT5uhhTeUBwTC44k6shHqslrjF_drfTukYZHBiZJevJ3iGlxkYjIGOzoyOQPCcUYuKr6NGUkNU/s1600/Thanos.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="422" data-original-width="759" height="177" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfbCwK5E5WpNmhsjpQJHHTR6oVg5h2i1hv4qqppQAH1fZP2J28UeGvtrLq7bMEItqeiYT5uhhTeUBwTC44k6shHqslrjF_drfTukYZHBiZJevJ3iGlxkYjIGOzoyOQPCcUYuKr6NGUkNU/s320/Thanos.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Thanos, the Mad Titan, disappointed with his namesake.</td></tr>
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A new dinosaur was published today in <u>Historical Biology</u>: <i><a href="https://www.tandfonline.com/doi/full/10.1080/08912963.2018.1546700">Thanos simonattoi</a></i>, named after Sergio Simonatto, who discovered the specimen, but more visibly Thanos, the Marvel villain. It might not shock you to known that Rafael Delcourt's name is on this paper. A few months ago, he gave us the <a href="https://www.nature.com/articles/s41598-018-28154-x">Etrigansauria</a>, an <a href="http://theropoddatabase.blogspot.com/2018/06/etrigansauria-unnecessary-demon.html">unnecessary name</a> that has designs on replacing the perfectly-good Neoceratosauria. Delcourt & Vidoi lori (2018) identify <i>Thanos </i>as an abelisaurid close to Brachyrostra. This all seems fine until you see the holotype:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-O6AhFhNzQ4d5qy_Jjm7okQHTADXJ21H5beO28iUEkA6lXLCGxxifAXS6x4opr2rL5hIsIJlb54RIue9otd1mbXfmSl5po7y69_CRCL5Wv-0BrXYBqacbokW8QufR055LWiqWQyLSueY/s1600/Thanos+3.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1322" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-O6AhFhNzQ4d5qy_Jjm7okQHTADXJ21H5beO28iUEkA6lXLCGxxifAXS6x4opr2rL5hIsIJlb54RIue9otd1mbXfmSl5po7y69_CRCL5Wv-0BrXYBqacbokW8QufR055LWiqWQyLSueY/s320/Thanos+3.jpg" width="264" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">That sure is a fossil.</td></tr>
</tbody></table>
<i>Thanos</i> is an atlas-axis complex.<br />
<br />
To my mind, you don't just stick the name Thanos on any old fossil that comes out of the ground. You save it for a fossil that justifies the name. Thanos wiped out half of all life in the universe with a snap of his fingers. He has a very distinctive face marked with furrows. He is the Avengers' greatest foe, and one of the medium's most enduring villains, period. <i>You don't give his name to a partially-preserved atlas-axis complex</i>.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVTlfD5rv2KsudfZwFW2Dm59noIGM8De_TorDlMhjc6U_BG4Y0XKzIsIsbF9YTJ2YTgBADN3rPMGqHi1cc9dqrJE5COXFXzR8rX-q3aLEWseNWiYbmMWhz_Y4pZxyni2bp1loq_A6w354/s1600/Thanos+2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="464" data-original-width="825" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVTlfD5rv2KsudfZwFW2Dm59noIGM8De_TorDlMhjc6U_BG4Y0XKzIsIsbF9YTJ2YTgBADN3rPMGqHi1cc9dqrJE5COXFXzR8rX-q3aLEWseNWiYbmMWhz_Y4pZxyni2bp1loq_A6w354/s320/Thanos+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Are you kidding me with this shit?"</td></tr>
</tbody></table>
And it's a real shame, because Thanos' furrowed brow and chin <i>do</i> lend themselves to abelisaurids, what with their rugose, furrowed skull bones. But we may never find out what <i>Thanos</i> looks like because even if a more complete abelisaur is dug out of the Sao Jose do Rio Preto Formation, without a preserved atlas-axis, <i>there's no way to tell if it's Thanos or not</i>. Any reference to <i>Thanos</i> will necessarily be provisional. Why did Delcourt & Vidoi loci even give this thing a species name instead of referring it to Abelisauridae <i>and leaving it at that until better material showed up?</i><br />
<br />
YOU DON'T HAVE TO NAME THESE THINGS.<br />
<br />
It really feels like Delcourt had the name "Thanos" in his back pocket, ready to deploy as soon as a new abelisaurid turned up whether or not the name fit the specimen. That's kind of how I feel about Etrigansauria, too, because <a href="https://en.wikipedia.org/wiki/Etrigan_the_Demon">Etrigan the Demon </a>is not a great namesake for the Neoceratosauria. Why? Because only two members of the Neoabelisauridae have horns: <i>Ceratosaurus</i> towards the bottom and <i>Carnotaurus</i> at the top, and those horns are not homologous. Horns are the exception, not the rule when it comes to Neoabelisaurids. Ironically, "Thanosauria" would've been a far more apt name, as most abelisaurids are characterized by rugose, furrowed skull bones. Delcourt wants to name dinosaurs after comic book characters, and this is a practice I fully endorse, but don't just do it willy-nilly; please, for the love of Arceus, make sure the animal(s) fits the name.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-2BYgeefcdcYa9_z4RWe3Zep0Ns97jZEK_FR189DwNtlXpnu_pnnxtxEiAUj3LPdxr180rzNn4xk7Tfx3QXiiJM-G4cBZqLptnscA6SyV5tIsmIcrx35UyYd6hS6azhzc229kPIaN7wM/s1600/Thanos+4.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="901" data-original-width="1536" height="187" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-2BYgeefcdcYa9_z4RWe3Zep0Ns97jZEK_FR189DwNtlXpnu_pnnxtxEiAUj3LPdxr180rzNn4xk7Tfx3QXiiJM-G4cBZqLptnscA6SyV5tIsmIcrx35UyYd6hS6azhzc229kPIaN7wM/s320/Thanos+4.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is apparently what <i>Thanos</i> looked like.</td></tr>
</tbody></table>
Delcourt & Vidoi loca end their paper with a lovely restoration of <i>Thanos</i> approaching some titanosaurs by Deverson da Silva. It's a nice image, but wholly and unfortunately speculative because, again, all we've got is an atlas-axis complex from this animal.<br />
<br />
I can't wait to read about <i>Darkseid</i>, the holotype of which will be a frontal bone.Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com8tag:blogger.com,1999:blog-4675540394850433221.post-25974472774015828622018-10-23T15:52:00.002-07:002018-11-27T11:12:29.280-08:00They Might Be Giants<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiG8vCOrVOrRcF0_NLrtyegxA40PfwoB4aNbGJ5fTllqOx7Uo7dcr8DlBVvHMXnePwOB4alHkiYI6N4wLuTUXE1ooHThnxle_uYfC9tdovJ1_G47Xwh8GTJ1XbhxWWnDkL_7xDpRZnfPqc/s1600/Ingentia+Pic.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="297" data-original-width="1024" height="115" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiG8vCOrVOrRcF0_NLrtyegxA40PfwoB4aNbGJ5fTllqOx7Uo7dcr8DlBVvHMXnePwOB4alHkiYI6N4wLuTUXE1ooHThnxle_uYfC9tdovJ1_G47Xwh8GTJ1XbhxWWnDkL_7xDpRZnfPqc/s400/Ingentia+Pic.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Ingentia prima</i> by Jorge Gonzalez</td></tr>
</tbody></table>
Two recent news stories perked my interest recently—the
descriptions of two new non-sauropod sauropodomorphs: <i style="mso-bidi-font-style: normal;">Ingentia prima</i> from the Late Triassic of Argentina and <i style="mso-bidi-font-style: normal;">Ledumahadi mafube</i> from the Early
Jurassic of South Africa. Together, these animals (and two others which I’ll
get to) form a clade of non-sauropod sauropodomorphs that achieved gigantism
independently from true, blue sauropods, which is intriguing for a
number of reasons.<br />
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<o:p></o:p></div>
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<a name='more'></a><br />
First, let’s get some terminology out of the way. I’m going
to use the phrase “prosauropod” as a term of convenience here to mean “every
non-sauropod sauropodomorph.” This is more or less how the term has been used
for a very long time—animals like <i style="mso-bidi-font-style: normal;">Plateosaurus</i>,
<i style="mso-bidi-font-style: normal;">Massospondylus</i>, and <i style="mso-bidi-font-style: normal;">Anchisaurus</i> were referred to as
“prosauropods” in a paraphyletic sense but the paraphyletic nature of the group
is well-established. “Prosauropods” constitute a loose amalgamation of taxa
that form a stepwise sequence from <i style="mso-bidi-font-style: normal;">Buriolestes</i>
to actual basal sauropods like <i style="mso-bidi-font-style: normal;">Vulcanodon</i>.
The actual line in the sand between “derived prosauropod” and “basal sauropod”
is becoming somewhat difficult to draw—a few key taxa (<i style="mso-bidi-font-style: normal;">Aardonyx, Melanosaurus</i>, <i style="mso-bidi-font-style: normal;">Vulcanodon</i>)
move between these branches with some fluidity from phylogeny to phylogeny which we’ll get to.<br />
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<o:p></o:p></div>
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<br /></div>
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Let’s talk about lessemsaurids.<o:p></o:p></div>
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<br /></div>
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Along with its neighbors, <i style="mso-bidi-font-style: normal;">Riojasaurus incertus</i> and <i style="mso-bidi-font-style: normal;">Coloradisaurus
brevis</i>, <i style="mso-bidi-font-style: normal;">Lessemsaurus sauropoides</i>
was named by Bonaparte for material found in the Late Triassic Los Colorados
Formation of Argentina (<a href="https://paleoglot.org/files/Bonaparte_99.pdf">Bonaparte, 1999</a>). The holotype of the latter consists
merely of eight pre-sacral neural arches <i style="mso-bidi-font-style: normal;">which
isn’t a lot to go on</i> <i style="mso-bidi-font-style: normal;">but who am I to
judge</i>? Bonaparte referred more material to <i style="mso-bidi-font-style: normal;">Lessemsaurus</i> in that initial description, and a 2007 redescription
of the taxon (<a href="https://www.researchgate.net/publication/230213248_New_information_on_Lessemsaurus_sauropoides_Dinosauria_Sauropodomorpha_from_the_Upper_Triassic_of_Argentina">Pol & Powell</a>) includes a scapula, humerus, radius & ulna,
some finger bones, a largely-complete right half of the pelvis, a femur, both
tibiae, the astragalus, and several foot bones.<o:p></o:p></div>
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Bonaparte originally referred <i style="mso-bidi-font-style: normal;">Lessemsaurus</i> to the Melanorosauridae which, in 1999, may or may not
have been a monophyletic group seeing as the very meaning of “prosauropod” was
in flux. Y<a href="https://www.academia.edu/1355818/The_earliest_known_sauropod_dinosaur_and_the_first_steps_towards_sauropod_locomotion">ates & Kitching (2003)</a> noted that <i style="mso-bidi-font-style: normal;">Lessemsaurus</i> and their new taxon, <i style="mso-bidi-font-style: normal;">Antetonitrus ingenipes</i>, shared a distally flared dorsal neural
spine. Pol & Powell (2007), thanks to the new <i style="mso-bidi-font-style: normal;">Lessemsaurus </i>material, find additional characters that match it and
<i style="mso-bidi-font-style: normal;">Antetonitrus</i> but are absent in more
traditional “prosauropods,” indicating that these two taxa are closer to
Sauropoda than other prosauropods.<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuiIP9W6DZYuGadC_BsqkWsTQXvlXOG5vuOXEiHeFhxlFgIo5uK1VQhECjkGlmrx56ckvye3hWAhT4NZDp4Zo8VOQ2hIDVQNU0xHA75-117YaTGGdW_JhnvpNqcZZ99sJm1mhFxXo-hwI/s1600/Antetonitrus.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1072" data-original-width="1600" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuiIP9W6DZYuGadC_BsqkWsTQXvlXOG5vuOXEiHeFhxlFgIo5uK1VQhECjkGlmrx56ckvye3hWAhT4NZDp4Zo8VOQ2hIDVQNU0xHA75-117YaTGGdW_JhnvpNqcZZ99sJm1mhFxXo-hwI/s320/Antetonitrus.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The known material of <i>Antetonitrus</i></td></tr>
</tbody></table>
Onward to <i style="mso-bidi-font-style: normal;">Antetonitrus
ingeipes</i>, then. This is a large prosauropod from South Africa. Yates &
Kitching (2003) describe several disarticulated vertebrae, a couple ribs, a
partial scapula, a pubis, and most of the limb bones. They refer a second,
smaller, specimen to the same taxon, and it may represent a subadult, as both
were found at the same site. The larger individual was still growing when it
died, as the neurocentral sutures of the cervical and dorsal vertebrae are
still open. It’s a shame that the hand is mostly unknown, but the preserved
metacarpals I & II indicate that <i style="mso-bidi-font-style: normal;">Antetonitrus</i>
still had a grasping hand with a divergent thumb. The arm bones and hindlimbs,
however, do show signs of true sauropod-ness: according to the authors, this
animal was almost certainly a full-time quadruped. The shape of the radius,
however, suggests that <i style="mso-bidi-font-style: normal;">Antetonitrus</i>
was able to pronate its hand at will, meaning that its forelimb was still being
used for things other than just carrying weight (perhaps attacking <i style="mso-bidi-font-style: normal;">Zupaysaurus</i> with its enormous thumb claw).</div>
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<o:p></o:p></div>
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Yates & Kitching find <i style="mso-bidi-font-style: normal;">Antetonitrus</i> between <i style="mso-bidi-font-style: normal;">Melanorosaurus</i>
and <i style="mso-bidi-font-style: normal;">Isanosaurus</i> in a stepwise series
towards Eusauropoda; in their phylogeny, <i style="mso-bidi-font-style: normal;">Anchisaurus</i>
is the most basal true sauropod. One thing that made me smile is that the
authors peg <i style="mso-bidi-font-style: normal;">Azendohsaurus laarousii</i> and
two unnamed forms from Madagascar as “fragmentary basal sauropodomorphs
of…indeterminate systematic position.” In fact, we would later find out that
they’re not dinosaurs at all!<o:p></o:p></div>
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<br /></div>
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<a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/zoj.12127">McPhee et al. (2014)</a> later published a lengthy paper
detailing the osteology of <i style="mso-bidi-font-style: normal;">Antetonitrus</i>
and further tested its phylogenetic position. Notably, they find that three
individuals—not two—are present in the remains. The authors more or less
torpedo the notion of a monophyletic Prosauropoda, although some small
monophyletic groups remain (Plateosauridae, Massospondylidae). To deal with <i style="mso-bidi-font-style: normal;">Lessmsaurus</i> and <i style="mso-bidi-font-style: normal;">Antetonitrus</i>, McPhee et al. reintroduce an older phylogenetic node
called Sauropodiformes, which for our purposes essentially separates the traditional
“prosauropods” from the “basal sauropods” of Yates & Kitching (<i style="mso-bidi-font-style: normal;">Anchisaurus</i>, <i style="mso-bidi-font-style: normal;">Melonosaurus</i>) from the true Sauropoda—here inclusive of <i style="mso-bidi-font-style: normal;">Gongxianosaurus, Vulcanodon, Isanosaurus</i>,
and then Eusauropoda. Their basalmost eusauropod is <i style="mso-bidi-font-style: normal;">Tazoudasaurus</i>.<o:p></o:p></div>
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I like this approach, which recognizes the paraphyly of
non-sauropod sauropodomorphs while still recognizing that the larger, more
sauropod-like taxa occupied a sort of (here we go) transitional morphology, yet
this “middle of the road” group is not, in McPhee et al.’s phylogeny,
monophyletic.<o:p></o:p></div>
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They write that:<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal" style="margin-bottom: 8.0pt; margin-left: .5in; margin-right: .5in; margin-top: 0in;">
…the basal sauropodiform hand represents a functional
trade-off between the need to retain manual dexterity and mobility whilst
providing an important auxiliary role in resisting large loading stresses…” and
that <i style="mso-bidi-font-style: normal;">Antetonitrus</i> is a critical taxon
in understanding this transition. <i style="mso-bidi-font-style: normal;">Antetonitrus</i>
and its closest relatives retained a grasping forelimb and probably the ability
to switch to bipedal locomotion when the need arose (like running away from rauisuchids).<o:p></o:p></div>
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<br />
Then, just about a month ago, a new challenger entered the
ring: <i style="mso-bidi-font-style: normal;">Ingentia prima</i>, a very large
non-sauropod sauropodiform (<a href="https://www.researchgate.net/publication/326272978_An_early_trend_towards_gigantism_in_Triassic_sauropodomorph_dinosaurs">Apaldetti et el. 2018</a>) along with three new
specimens of <i style="mso-bidi-font-style: normal;">Lessemsaurus</i> which
together demonstrate that non-sauropod sauropodiforms grew very large very
fast, reaching sizes that true, blue sauropods wouldn’t achieve until well into
the Jurassic. Based on histologic sampling, Apaldetti et al. propose that <i style="mso-bidi-font-style: normal;">Lessemsaurus</i> weighed upwards of seven
tons as an adult, which is even larger than basal true sauropods.* </div>
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<br /></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoVSIAEqT64PTMUBhxXwB3bB2HwoGOIpwcpKqxhYor3oyrdpdNvWuNI7mMuwmcB7V2KpQKkhjXufUzmbpqSsp7ethrMkh840RCwidf7F-U02AJ6Cxi0aZ9-K-22zKa14_YpzOhFilRT3U/s1600/Ingentia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="778" data-original-width="1600" height="155" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoVSIAEqT64PTMUBhxXwB3bB2HwoGOIpwcpKqxhYor3oyrdpdNvWuNI7mMuwmcB7V2KpQKkhjXufUzmbpqSsp7ethrMkh840RCwidf7F-U02AJ6Cxi0aZ9-K-22zKa14_YpzOhFilRT3U/s320/Ingentia.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Skeletal diagram and selected bones from <i>Igentia</i></td></tr>
</tbody></table>
The paper
introduces <i style="mso-bidi-font-style: normal;">Ingentia </i>but it’s really
more concerned with the new <i style="mso-bidi-font-style: normal;">Lessemsaurus</i>
material. <i style="mso-bidi-font-style: normal;">Ingentia</i>, <i style="mso-bidi-font-style: normal;">Lessemsaurus,</i> and <i style="mso-bidi-font-style: normal;">Antetonitrus</i> were found to be sister taxa in Apaldetti et al.’s
analysis, in a monophyletic clade the authors name “Lessemsauridae,” and that
this group constitutes either the basalmost group of true sauropods or the
closest relative of true sauropods, depending on the definition of Sauropoda
you’re using (taxonomy!).<br />
<o:p></o:p></div>
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<br /></div>
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The group has an interesting growth strategy: while normal
sauropods grew at a fast, but constant rate towards adulthood, these
lessemsaurids had “cyclical and remarkably high growth rates.” In other words,
between the lines of arrested growth, they did a LOT of growing. They also have
pneumatic cervical and (in <i style="mso-bidi-font-style: normal;">Antetonitrus</i>)
dorsal neural arches, and thus had evolved at least the beginnings of an avian-style respiratory system,
or at least the beginnings of it. Interestingly, lessemsaurids did not have very
long necks and may not have engaged in the sort of bulk feeding that true
sauropods specialized in. While there is no skull material known for
lessemsaurids, close relative <i style="mso-bidi-font-style: normal;">Aardonyx
celestae</i> (<a href="http://rspb.royalsocietypublishing.org/content/early/2009/11/09/rspb.2009.1440">Yates et al. 2010</a>) has a triangular snout in dorsal view, indicating that it was more
selective in its grazing than true sauropods (but read on). <o:p></o:p></div>
<div class="MsoNormal">
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEt-OI-fqhSz6DpuhW2NHFSOybcUWIsb8zuZ04yae6A0GUmFxQvFi2DftiCDEhnzPw8_ol3AcqnX8d-7_Kt5laK7KN67yfB58IT1cvy-gH3rAafLQBzjm9QiGUcr1T5fkZa8lgU_VXFPA/s1600/Ludumahadi.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="922" data-original-width="1600" height="184" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEt-OI-fqhSz6DpuhW2NHFSOybcUWIsb8zuZ04yae6A0GUmFxQvFi2DftiCDEhnzPw8_ol3AcqnX8d-7_Kt5laK7KN67yfB58IT1cvy-gH3rAafLQBzjm9QiGUcr1T5fkZa8lgU_VXFPA/s320/Ludumahadi.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Skeletal and bones of <i>Ludumahadi</i></td></tr>
</tbody></table>
And then, just a few weeks after <i style="mso-bidi-font-style: normal;">Ingentia</i> was described, yet another enormous, but quite fragmentary, lessemsaurid was
published: <i style="mso-bidi-font-style: normal;">Ledumahadi mafube</i> (<a href="https://www.cell.com/current-biology/pdf/S0960-9822(18)30993-X.pdf">McPheeet al. 2018</a>) that tips the scales at twelve tons! The authors also attempted to
better understand the change in posture from “prosauropod” to true sauropods by
correlating humeral and femoral circumference with quadrupedal or bipedal
postures in a large sample of eighty-one dinosaurs, hundreds of mammals, and
several large-bodied reptiles. Applying this technique to sauropodomorphs, they
find that while most prosauropods were bipeds, a few lineages (<i style="mso-bidi-font-style: normal;">Jingshanosaurus, Anchisaurus, Riojasaurus</i>)
went quadrupedal—as did lessemsaurids. McPhee et al. note that this contradicts
osteological markers indicating at least facultative bipedality in lessemsaurids,
like the grasping hand that could not fully pronate. The authors have some
suggestions as to why this might be, but I think more research and better
lessemsaurid hand material would be helpful, specifically of the hands and wrists.</div>
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<o:p></o:p></div>
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<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmOIpwZBhzNKfDzg_piLF6JmfepyjUBYmT7D77_h8eACXG5HoDFIVYEsAgEbYBGCegU6qJBjvqJ1sfpGned2sVW9xyyNezQm9LGPaZhC1DT_T6dIR6AoTuF69NY3jB7rjYR4TyrVIwqfw/s1600/Aardonyx+Skull.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="264" data-original-width="448" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmOIpwZBhzNKfDzg_piLF6JmfepyjUBYmT7D77_h8eACXG5HoDFIVYEsAgEbYBGCegU6qJBjvqJ1sfpGned2sVW9xyyNezQm9LGPaZhC1DT_T6dIR6AoTuF69NY3jB7rjYR4TyrVIwqfw/s320/Aardonyx+Skull.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skull of potentially close relative <i>Aardonyx</i></td></tr>
</tbody></table>
Both McPhee et al. (2018) and Apaldetti et al. (2018) comment that gigantism--at least up to twelve tons--is not dependant on bulk-feeding or having columnar limbs: while there's no skull material for lessemsaurids (that I'm aware of), the animals around them, like <i>Aardonyx</i>, have snouts that narrow to a point, implying more selective feeding. While lessemsaurids do have a more sauropod-like fourth trochanter, their femora are more sigmoid than straight. I also wonder exactly what they were doing with their forearms. While there's not a lot of hand bones known for this group, <i>Antetonitrus</i> has an opposable thumb and <i>Ludumahadi</i> might also, although its metacarpal I is a different shape than in <i>Antetonitrus</i> and proportionately longer. <i>Ingentia</i> supplies all five metacarpals but no finger bones; its metacarpal I is "notably robust" and wider than it is long, generally similar to other "prosauropods."</div>
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Apaldetti et al. (2018) note that, in <i>Ingentia</i> at least, the forelimbs were incapable of an erect posture and the hand could not be fully pronated. It's clear that <i>Antetonitrus</i> had a divergent thumb, so grasping was still in the cards. And it's entirely possible that these taxa had different hand morphologies: <i>Antetonitrus</i> is the smallest (but still large) but <i>Ludumahadi</i> is largest and may have a more sauropod-like hand--independently derived, of course.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggKH0A6RutPC1hNkkH-WZly__sdz5G8wE6z_f1718K32RZX9BWjlLrd_hN0XycAV5ozH-5d6zNATRhVUuQoLUp9dnTrks7AOJu2yZtNUt1uK6B7GV-e2_6_jtVyeQUfarfVP0N2QAqJII/s1600/Aardonyx.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="150" data-original-width="600" height="100" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggKH0A6RutPC1hNkkH-WZly__sdz5G8wE6z_f1718K32RZX9BWjlLrd_hN0XycAV5ozH-5d6zNATRhVUuQoLUp9dnTrks7AOJu2yZtNUt1uK6B7GV-e2_6_jtVyeQUfarfVP0N2QAqJII/s400/Aardonyx.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A skeletal of <i>Aardonyx</i>, who seems to be bipedal</td></tr>
</tbody></table>
Even in <i>Antetonitrus</i>, though, what was the hand's normal posture? The thumb is divergent, not contributing to weight-bearing, digits II and III must have been the weight-bearing digits, digit IV is usually quite small in non-sauropodomorphs but maybe it was elongate in this group to help bear weight? Finally, digit V is little more than a metacarpal with a nubbin at the end. I may be overthinking this, though: ankylopollexian ornithopods were often enormous and their three middle digits seem to have done a fine job of holding them up. Maybe lessemsaurids had iguanodont-like hands (given that thumb claw)? Was <i>Shantungosaurus</i> limited to full-time quadrupedality?<br />
<span style="text-indent: -0.25in;"><br /></span>
<span style="text-indent: -0.25in;">Finally, I wonder what triggered gigantism in this
group in the first place. One of the benefits of getting larger
is that your digestive system </span><i style="text-indent: -0.25in;">also</i><span style="text-indent: -0.25in;">
gets larger, allowing you to better handle bulk-feeding, which is a theory applied to sauropods and why they got bigger. Of course, another
huge benefit to becoming large is that once you weigh more than the local
predators, you don’t have to worry that much about being preyed upon. The Los
Colorados Formation is home to </span><i style="text-indent: -0.25in;">Zupaysaurus</i><span style="text-indent: -0.25in;">
and </span><i style="text-indent: -0.25in;">Powellvenator</i><span style="text-indent: -0.25in;"> (coelophysoids) as
well as </span><i style="text-indent: -0.25in;">Riojasuchus</i><span style="text-indent: -0.25in;"> (a mid-sized ornithosuchid).
Given the general agreement that they weren't bulk-feeding, I’m more inclined to
chalk lessemsaurid gigantism up to predator avoidance. This is indirectly
supported by their high growth rate—get bigger faster before something eats you!</span></div>
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<o:p></o:p></div>
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There's a lot more I could say about this, including talking about <i>Aardonyx</i>, another of these borderline taxa that tend to move around the tree, but this post has already gotten out of hand. The moral of the story is that sauropods weren't the only sauropodomorphs to get huge--non-sauropod sauropodiforms did it, too!</div>
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*The authors don’t actually calculate the weight of <i style="mso-bidi-font-style: normal;">Igentia</i>, which is weird, unless I missed
it. <o:p></o:p></div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com0tag:blogger.com,1999:blog-4675540394850433221.post-68769609105282169402018-09-07T15:03:00.001-07:002018-09-07T15:03:24.047-07:00An Update on Stem Turtles<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNqCWwKRPtcAnn1QEKqpHdIXyivv-9UawvdTP1Fgi6akphRmALozrjC1-glDdR7-_AnpyGwLd1LPF4-rO99_csxOwAyn9FO-7LAFgi8QNipaQRd2RF2eO9M3rHB_11trLDyF3jyUJLxhc/s1600/Eorhynchochelys+Head.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="351" data-original-width="624" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNqCWwKRPtcAnn1QEKqpHdIXyivv-9UawvdTP1Fgi6akphRmALozrjC1-glDdR7-_AnpyGwLd1LPF4-rO99_csxOwAyn9FO-7LAFgi8QNipaQRd2RF2eO9M3rHB_11trLDyF3jyUJLxhc/s320/Eorhynchochelys+Head.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The beaky noggin of <i>Eorhynchochelys</i> by...IVPP?<br /><br /><div style="text-align: center;">
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</tbody></table>
Couple things I need to talk about. First, it's been a very long time since I've blogged, which was not my intention (it never is). I hit a rough patch of writer's block, which was followed up by a 9-day stint at the hospital where I got a CF-related tune-up. Taxonomy Tuesday is not proving to be the rich well of inspiration I was hoping for, so while I still intend to write up Taxonomy Tuesdays, they almost certainly won't be weekly. Now then, right before I was admitted, I wrote this short post about a new stem turtle. I wrote about turtle origins <a href="https://waxing-paleontological.blogspot.com/2015/10/the-secret-origin-of-tmnt.html">way back in 2015</a> and I'm always excited when a new one pops up. Thankfully, in addition to this post, I'm halfway through essays about mesosaurs and tanystropheids, so regular blogging will commence soon.<div>
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In my previous stem-turtle post, we went through the basalmost stem-turtles: <i style="mso-bidi-font-style: normal;">Eunotosaurus</i>, <i style="mso-bidi-font-style: normal;">Pappochelys</i>, and <i style="mso-bidi-font-style: normal;">Odontochelys</i>.
Since that post, a full description of <i style="mso-bidi-font-style: normal;">Pappochelys</i>
has seen print (<a href="https://www.tandfonline.com/doi/abs/10.1080/14772019.2017.1354936?journalCode=tjsp20">Schoch & Sues, 2017</a>) that confirms its diapsid status. It
also has a large, and ventrally-open, lower temporal fenestrae like lizards and
thalattosaurs. To be fair, <i style="mso-bidi-font-style: normal;">Eunotosaurus</i>
also has this condition but it’s constructed a bit differently. Here’s their
reconstruction of the whole skeleton of <i style="mso-bidi-font-style: normal;">Pappochelys</i>:<o:p></o:p></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf3OR8vMffNNgxNNQXTo6Fd7C3P3oCwj2Dj3kim4X7cwS8IXw2mZDahEVZzLtlIETmhEZXH86_5lPgwoCP6qnJMgI6DHXLeoaxpSUcgt87szVcXkqToq3Bf5X3AAyYQWh0KVygiD_M7eo/s1600/Pappochelys.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1224" data-original-width="1000" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf3OR8vMffNNgxNNQXTo6Fd7C3P3oCwj2Dj3kim4X7cwS8IXw2mZDahEVZzLtlIETmhEZXH86_5lPgwoCP6qnJMgI6DHXLeoaxpSUcgt87szVcXkqToq3Bf5X3AAyYQWh0KVygiD_M7eo/s320/Pappochelys.jpg" width="261" /></a></div>
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Cool, right? In particular, the gastralia are starting to
take on a larger role, and the enlarged interclavicle doesn’t look all that
different from what you see on the anterior end of normal turtle plastron.
Notably, it doesn’t seem to have any overtly aquatic adaptations, although
Schoch & Sues (2015) suggest that its enlarged ribs and gastralia were
adaptations to provide ballast in an aquatic setting. It is apparently the most
common fossil reptiles in the Velberg lake deposit, “which suggests that it either
lived along the lakeshore or frequently entered the lake.” </div>
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<a href="https://www.cell.com/current-biology/abstract/S0960-9822(16)30478-X">Lyson etal. (2016)</a> write that <i>Pappochelys</i> is
found in lacustrine sediments “associated with fully terrestrial animals” while <i>Eunotosaurus</i>, is apparently commonly found in terrestrial floodplain deposits, so
perhaps stem turtles were primarily terrestrial but not above foraging
underwater from time to time. In this scenario, <i>Odontochelys</i> would be an early pioneer into the marine sphere.</div>
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A NEW CHALLENGER APPROACHES<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWlesE1hnOMqFOJAl2MLC83fcHpEHMaKL9-hmr81Ww0ZgbE7Hf-u2rv7ZkkdwwnU0BVuFziVJw98mNZfbOgk3feWrQA32EfuJ3F8WlyDjKRVVHHFDTnd2s071cn7UFh71-bdIa0OHKJkw/s1600/Eorhynchochelys+Skeleton.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="472" data-original-width="800" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWlesE1hnOMqFOJAl2MLC83fcHpEHMaKL9-hmr81Ww0ZgbE7Hf-u2rv7ZkkdwwnU0BVuFziVJw98mNZfbOgk3feWrQA32EfuJ3F8WlyDjKRVVHHFDTnd2s071cn7UFh71-bdIa0OHKJkw/s320/Eorhynchochelys+Skeleton.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">SMMP 000016, aka <i>Eorhychochelys sinensis</i></td></tr>
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This week saw the publication of another stem-turtle, <i>Eorhynchochelys sinensis </i>(<a href="https://www.nature.com/articles/s41586-018-0419-1">Li et al., 2018</a>), from the lower
Carnian of China’s Guizhou Province. Interestingly, it comes from beds
approximately 7.5 meters below where they found <i>Odontochelys</i>. It’s the earliest turtle with a beak, although that
beak is restricted to the tips of the upper and lower jaws.</div>
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<o:p></o:p></div>
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Unlike its cousins, <i style="mso-bidi-font-style: normal;">Eorhynchochelys</i>
is enormous, about 2.3 meters long (7.5 feet). Aside from its very wide body,
this stem-turtle has a surprisingly long tail, a short neck, and a bafflingly
small skull—just 9 centimeters long (about 3.5 inches). This reminds me of the
body-to-head proportions of <i style="mso-bidi-font-style: normal;">Cotylorhynchus</i>,
the pin-headed caseid. As I said, the small beak is restricted to the
premaxillae and anterior ends of the dentaries. The teeth are similar to those
in <i style="mso-bidi-font-style: normal;">Pappochelys</i> and <i style="mso-bidi-font-style: normal;">Odontochelys</i>. Note that <i style="mso-bidi-font-style: normal;">Odontochelys</i> is younger than <i style="mso-bidi-font-style: normal;">Eorhynchochelys</i> but does not have a
beak. Li et al. write the fully-toothed jaw of <i style="mso-bidi-font-style: normal;">Odontochelys</i> is likely a reversal, as is <i style="mso-bidi-font-style: normal;">Eorhynchochelys</i> having twelve dorsal vertebrae (every other stem
turtle has nine). Like in every other clade, there seems to be a good deal of
homoplasty at the base of “Pantestudines” (a clade name I really don’t like). <o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjphsChCKvbCGOcpQF_litYACmNevbRizwIf32xaM5aPETweJOLMLd9NWX6H7UDbj94uQZlIvs-g-6psgojXLpWKSxZzA6LiWLapBG5nj5QVjV69F91n3fW6KxUXopzLOdPM2YymBaIPdQ/s1600/Eorhynchochelys+Skull.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="671" data-original-width="650" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjphsChCKvbCGOcpQF_litYACmNevbRizwIf32xaM5aPETweJOLMLd9NWX6H7UDbj94uQZlIvs-g-6psgojXLpWKSxZzA6LiWLapBG5nj5QVjV69F91n3fW6KxUXopzLOdPM2YymBaIPdQ/s320/Eorhynchochelys+Skull.jpg" width="309" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The hilariously small skull of <i>Eorhychochelys</i> (snout pointing up)</td></tr>
</tbody></table>
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<i>Eorhynchochelys</i> is
also the earliest stem-turtle with a “puboischiadic plate,” a turtle feature
which represents yet another wholesale rearrangement of part of the skeleton to
deal with having an oversized, rigid torso. It does not, apparently have
something called a “separate hypoischium” which is present in <i>Odontochelys</i> and <i>Proganochelys</i>.</div>
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<o:p></o:p></div>
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The authors note that <i style="mso-bidi-font-style: normal;">Eorhynchochelys</i>’
broad ribs, stout limbs, and large claws point to a fossorial ecology, and that
it was most likely “predominantly terrestrial.” However, the fact that it
occurs in marine sediments and has a separated astragalus & calcaneum in
adulthood suggests at least <i style="mso-bidi-font-style: normal;">some</i>
aquatic adaptation. Merely being found in marine sediment doesn’t mean that <i style="mso-bidi-font-style: normal;">Eorhynchochelys</i> was primarily marine, of
course. As the authors state:<o:p></o:p></div>
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The new form may have been an
inhabitant of coastal waters foraging on land as well as in the water,
searching the mud along the shore using its powerful limbs in a way that many
living pond turtles also do.<o:p></o:p></div>
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In fact, in the supplementary information, Li et al. state
that the skeleton was probably transported from coastal waters to its final
resting place by currents and “does not represent” part of the local ecosystem.<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh36wMVOJhCm7ih5AI7G_2geK2kwJ99rUqeGqa2PJ-lpWmIeqRT-K0gzdbVt2bW3I_0xhrfCLUk_KrIFVP0_DnCy3O7ygQSIQ6PUzEku8-De0vEq9jDlTWl26urkNOB_U5B1KI33-AuU-w/s1600/Eorhynchochelys+Marine.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="765" data-original-width="1600" height="153" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh36wMVOJhCm7ih5AI7G_2geK2kwJ99rUqeGqa2PJ-lpWmIeqRT-K0gzdbVt2bW3I_0xhrfCLUk_KrIFVP0_DnCy3O7ygQSIQ6PUzEku8-De0vEq9jDlTWl26urkNOB_U5B1KI33-AuU-w/s320/Eorhynchochelys+Marine.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Image credit: IVPP again (do they just not credit artists over there?)</td></tr>
</tbody></table>
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So of course every piece of paleoart I’ve seen that
accompanies popular science articles about <i>Eorhynchochelys</i>
shows it as a marine animal, swimming around as though that’s obviously what it
was adapted for. I have yet to see a piece of paleoart depicting it as a
beach-combing digger, which is disappointing. In fact, this excellent picture
of <i>Eunotosaurus</i> by Andrey Atuchin
(from 2016) is the only stem-turtle restoration I’ve seen which advocates a
fossorial ecology. It bothers me.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9mr58C7N97aTn_wI6MGSeMO1SI4aETzOVb_lHIVuFIV5XuotvbD8YVV3VZC8fL9u5qZnvRj43lYPmPJFzHKX6mpIAF5BhgAt12N3REZvEhxxdhuFo1JI1CooGbhR9GMB7ncryjAVLuRc/s1600/Eunotosaurus.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="900" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9mr58C7N97aTn_wI6MGSeMO1SI4aETzOVb_lHIVuFIV5XuotvbD8YVV3VZC8fL9u5qZnvRj43lYPmPJFzHKX6mpIAF5BhgAt12N3REZvEhxxdhuFo1JI1CooGbhR9GMB7ncryjAVLuRc/s320/Eunotosaurus.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Maybe it's digging its way towards the sea.</td></tr>
</tbody></table>
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It still boggles my mind to consider that our knowledge of turtle origins has exploded in the last 10 years. Prior to 2008 (when <i>Odontochelys</i> was described), <i>Proganochelys</i> was still the best-known fossil turtle, and turtles were a relic group of anapsids related to pareiasaurs or millerettids (molecular evidence notwithstanding). Welcome to the club, <i>Eorhychochelys</i>--I have no doubt that more of your cousins are waiting in the ground or in museum collections to be found and described.</div>
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<o:p></o:p></div>
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Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com10tag:blogger.com,1999:blog-4675540394850433221.post-53592346918942481062018-07-26T13:42:00.003-07:002018-07-26T13:43:00.013-07:00Taxonomy Tuesday: Hyenas Are Not Dogs<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi39-gSKqSrwiXPE7M4zotCZjl9Zelm7_7c0BJiQOjCwVDmePT1RxMaXYjrmVTQRSCcF618IbpUd6qKBZi_Pityf1xhKNADkgkewQaE7lg0MZsZSSz4ehF2X6dBGDFhRz4Ffhg5e9mdjLM/s1600/Spotted+Hyena.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="644" data-original-width="1200" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi39-gSKqSrwiXPE7M4zotCZjl9Zelm7_7c0BJiQOjCwVDmePT1RxMaXYjrmVTQRSCcF618IbpUd6qKBZi_Pityf1xhKNADkgkewQaE7lg0MZsZSSz4ehF2X6dBGDFhRz4Ffhg5e9mdjLM/s320/Spotted+Hyena.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The spotted, or "laughing" hyena</td></tr>
</tbody></table>
Yes, I know it's Thursday. I got busy mid-week. Today's #TaxonomyTuesday is about hyenas, which, contrary to popular belief, are not related to dogs.<br />
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Hyenas are familiar African predators that are best known
for scavenging, although they don’t actually scavenge most of their food. There
are four living hyenas: the spotted or laughing hyena (<i style="mso-bidi-font-style: normal;">Crocuta crocuta</i>), brown hyena (<i style="mso-bidi-font-style: normal;">Parahyaena
brunnea</i>), striped hyena (<i style="mso-bidi-font-style: normal;">Hyaena
hyaena</i>), and aardwolf (<i style="mso-bidi-font-style: normal;">Proteles
cristatus</i>). The striped hyena is also found in the Middle East and India.
In general, hyenas are fairly large, dog-like animals with lengthy forelimbs
and sloped backs (rather like a German Shepherd) and powerful, bone-cracking
dentition. The aardwolf is the black sheep of the family, being much smaller
than its cousins and subsists almost entirely on termites—apparently they won’t
voluntarily eat meat.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJwS7WePwiV-29-2BSX41LCIhP2NzyZKVLhGwMggp3KugCoxjDAg2e3-x2dQMiCnezWZRTf7V-noXW08kNll-K7enzKQ4-jD4VQ2dp72Ko4vAAMwPU8A7otyCbj6hm32tpf1s7tRGybpU/s1600/Aardwolf.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="386" data-original-width="550" height="224" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJwS7WePwiV-29-2BSX41LCIhP2NzyZKVLhGwMggp3KugCoxjDAg2e3-x2dQMiCnezWZRTf7V-noXW08kNll-K7enzKQ4-jD4VQ2dp72Ko4vAAMwPU8A7otyCbj6hm32tpf1s7tRGybpU/s320/Aardwolf.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The small, adorable aardwolf</td></tr>
</tbody></table>
Hyenas have an extensive fossil record going back to the
Miocene. Fossil hyenas are impressively diverse—<i style="mso-bidi-font-style: normal;">Chasmaporthetes </i>appears to have been a cheetah-like cursorial
hunter. The group’s bone-crunching contingent evolved some 10-12 million years
ago and appears to have outcompeted the more basal “dog-like” hyenas but were kept out of
North America by the successful bone-crunching borophagine
dogs, who were already filling that niche. The largest of the bone-crunchers, <i style="mso-bidi-font-style: normal;">Pachycrocuta</i>,
was a lion-sized carnivore that probably stole kills from machairodont cats throughout Eurasia and east Africa.<br />
<div class="MsoNormal">
<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOU_4WEENloezKa3wyOrOITvJNMXn4snbmJsnIvHAqx-K6zvgeUfOZkooqCiLMSL8RB3umr6J6mUXU6FDEu4nWr-zGEX0t5Hqjffs5grBigJH0SbwS39S7ytOx9C-Uoke5_kCFyiBVqSY/s1600/Pachycrocuta.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="324" data-original-width="604" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOU_4WEENloezKa3wyOrOITvJNMXn4snbmJsnIvHAqx-K6zvgeUfOZkooqCiLMSL8RB3umr6J6mUXU6FDEu4nWr-zGEX0t5Hqjffs5grBigJH0SbwS39S7ytOx9C-Uoke5_kCFyiBVqSY/s320/Pachycrocuta.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Pachycrocuta</i>, by Mauricio Anton</td></tr>
</tbody></table>
It’s completely reasonable to assume hyenas are
dogs. After all, the two groups share general body plans, non-retractable
claws, and dental features. In particular, their skulls are similar to borophagine dogs—not surprising given their similar bone-crunching lifestyles.</div>
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Surprisingly, however, hyenas are actually on the cat family tree. They’re
not cats per say, but if you think of dogs and cats as “end-points” on a
diverging family tree, hyenas are around mid-tier on the cat branch. This relationship is given
away by the morphology of their auditory bullae, or ear capsules. If you look
at the bottom of a dog or cat skull, you’ll see two inflated areas down by the
foramen magnum; this is where the ear bones live. In caniforms (dog branch),
they have single-chambered bullae. Feliforms (cat branch) have double-chambered
bullae, and it turns out that hyenas have double-chambered bullae.<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9oSel1E2YzumZeCqfxxRzOd3ZfU4CRXkt7LFWjBk5fv2YbdxnksWE7qKtQFqcKK2fi3u6wpXT4KV74c4NiXzkN1pgo5T6vXzVSA-TpMYPbkmBk0qfles36nPiJ5_-ffpkciLNN9RMDuU/s1600/Auditory+bullae.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="159" data-original-width="220" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9oSel1E2YzumZeCqfxxRzOd3ZfU4CRXkt7LFWjBk5fv2YbdxnksWE7qKtQFqcKK2fi3u6wpXT4KV74c4NiXzkN1pgo5T6vXzVSA-TpMYPbkmBk0qfles36nPiJ5_-ffpkciLNN9RMDuU/s1600/Auditory+bullae.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">You can see how the auditory bullae are divided in two here, from Wikipedia.</td></tr>
</tbody></table>
Hyenas are, thus, another good example of convergent
evolution. Because they adopt a similar ecological role as dogs, hyenas also
approach them in general morphology. This also underscores the importance of shared anatomical landmarks. Every monophyletic group is defined, or diagnosed, by one or more unique, shared features. Despite looking like dogs, hyenas have cat-type auditory bullae. In ceratopsians, it's the rostral bone (not horns or frills). In marsupials, it's a pouch (among other things). The thylacine, for instance, is (well, was) extremely similar to placental dogs like the red fox. However, it still had a pouch and reproduced the marsupial way. Another example is the similar body outlines of dolphins (which are mammals) and ichthyosaurs (which are reptiles). Turns out sharks (which are elasmobranchs) and tuna (which are actinopterygids) have similar outlines as well. None of them are closely related, but all four groups adapted to similar environmental conditions--that's just a very good shape for efficiently moving through and feeding in a marine environment.<br />
<br />
But dolphins are clearly mammals, ichthyosaurs are clearly reptiles, sharks are clearly cartilaginous fish, and tuna are clearly ray-finned fish. They all solved the ecological challenges in different ways before coming, more or less, to the same conclusion.<br />
<br />
This has gotten a little longer than I anticipated, but the point is that hyenas are not dogs; they're almost cats, and convergent evolution is super neat.</div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-36010223944737439902018-07-17T15:24:00.001-07:002018-07-18T09:21:07.617-07:00Taxonomy Tuesday: Snakes are lizards<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMrkDrn95zmpqstXlLmcKoYDd5xUfmGstv51_Ns98-dXlf4JtPJy_Uu6CmMUjJOPWhzFqmX-Zt7e-t6Cu0E3l2MYmEpRb4mnfse5afRpFP7-aF4n6ns154OhXZignoZO5hAQ_YFTzDaCE/s1600/Snek.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="490" data-original-width="768" height="204" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMrkDrn95zmpqstXlLmcKoYDd5xUfmGstv51_Ns98-dXlf4JtPJy_Uu6CmMUjJOPWhzFqmX-Zt7e-t6Cu0E3l2MYmEpRb4mnfse5afRpFP7-aF4n6ns154OhXZignoZO5hAQ_YFTzDaCE/s320/Snek.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Snek</td></tr>
</tbody></table>
I'm trying something new in an effort to post more often then once a month.<br />
<br />
Once a week, on "Taxonomy Tuesday," I'll write a short post about some taxonomic weirdness that people might not think about. On this maiden voyage of "Taxonomy Tuesday," we'll talk about snakes...which are lizards.<br />
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Now, when most people think about reptiles, they think about turtles, crocodilians, lizards, and snakes as if all four groups are wholly separate from each other (nobody ever thinks about amphisbaenians). The tree diagram in their heads looks something like this, as if snakes and lizards split from a common ancestor:<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN3NgXp5CvxcNltDFoazDj03PO6QgxINcKffIrTZpcD0mV9KUIRQ5Up2hZvCs1yvjwgltkmuau9vMcqkqF56MitZ3G9xGgGlRC7UYn3l-gghGseBCOEGrP0iYDOPAkqn7YLbPAISnfTww/s1600/Squamate+Tree+1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="550" data-original-width="864" height="203" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN3NgXp5CvxcNltDFoazDj03PO6QgxINcKffIrTZpcD0mV9KUIRQ5Up2hZvCs1yvjwgltkmuau9vMcqkqF56MitZ3G9xGgGlRC7UYn3l-gghGseBCOEGrP0iYDOPAkqn7YLbPAISnfTww/s320/Squamate+Tree+1.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Behold the magic of Microsoft Paint.</td></tr>
</tbody></table>
But in reality it's more like this:<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMY94EiXXMvaCCWnZXgXnbG7GFSoT6O8tazsQAG2yYrALcfv3GyVmweCB3qyjeCHT2R7zz3rPdmMKIdP5OMg78fIPeA0cZnEjXnf4noncbt9b_zN7-uCX5_NAByIDDF3dKJQ-k1C1l4-I/s1600/Squamate+Tree+2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="541" data-original-width="850" height="203" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMY94EiXXMvaCCWnZXgXnbG7GFSoT6O8tazsQAG2yYrALcfv3GyVmweCB3qyjeCHT2R7zz3rPdmMKIdP5OMg78fIPeA0cZnEjXnf4noncbt9b_zN7-uCX5_NAByIDDF3dKJQ-k1C1l4-I/s320/Squamate+Tree+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">I just realized I left off tuataras...which are not lizards.</td></tr>
</tbody></table>
"But snakes don't have legs!"<br />
<br />
Indeed they do not, but that can't be their <i>distinguishing</i> feature, because lizards lose their legs every chance they get. Among the more well-known examples of non-snake legless lizards are <a href="https://en.wikipedia.org/wiki/Anguis_fragilis">slow worms</a> and <a href="https://en.wikipedia.org/wiki/Glass_lizard">glass lizards</a>. They can be distinguished from snakes most readily by having eyelids, an external ear (snakes lack both of these) and a non-forked tongue. Apart from those two groups, however, there are many more lizards from diverse families that have also lost their limbs:<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilwXrqpEMMXUcqrnuAdL-u16kt0rtkxOtlovbDNzEI2nm2Krg2tG-dTaYxxKDNCI6UcVwEcdmVua5DmJ5cd7CQuikN4RNKBkWfvyLAdrQoPsnpvk38RcUpclt8BCo8bTT1UFg8i8IP47U/s1600/Lialis.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="432" data-original-width="720" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilwXrqpEMMXUcqrnuAdL-u16kt0rtkxOtlovbDNzEI2nm2Krg2tG-dTaYxxKDNCI6UcVwEcdmVua5DmJ5cd7CQuikN4RNKBkWfvyLAdrQoPsnpvk38RcUpclt8BCo8bTT1UFg8i8IP47U/s320/Lialis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Lialis</i>, a pygopodid gecko. IT'S A GECKO.</td></tr>
</tbody></table>
<ul>
<li>Pygopodids lack forelimbs entirely but have vestigal flaps for hindlimbs. Astoundingly, these lizards are <i>geckos</i>.</li>
<li>Dibamids are limbless and include species that are blind or nearly blind and deaf. They are specialized burrowers and may be the most basal living squamate group. They look like worms.</li>
<li>Anniellids, or the American legless lizards, are found exclusively in California.</li>
<li>Gymnophthalmids (GYM-noff-THAL-mids), or speckled lizards, is a large family that contains some species that have all four limbs and others with reduced limbs. Different taxa have different limb/less proportions.</li>
<li>Skinks, which make up a very large radiation of rather shiny-bodied lizards, include many groups that have independently lost their limbs, some of which only have tiny vestigal flaps remaining and others that have lost their limbs entirely.</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhesGBgzj4a2UlQPPdtPh6n6pS3g1FLlpCKfnsqqBZ4D6dm6jWgFbkw1UjXmFuMaMyeb427c-8VIFzC-jaKEPge4sNmHoJclu0lhdtLtohvOf4kAKBkUkxYbcIvpsmeERBYZfeWq3y45tU/s1600/Acontias.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="303" data-original-width="658" height="147" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhesGBgzj4a2UlQPPdtPh6n6pS3g1FLlpCKfnsqqBZ4D6dm6jWgFbkw1UjXmFuMaMyeb427c-8VIFzC-jaKEPge4sNmHoJclu0lhdtLtohvOf4kAKBkUkxYbcIvpsmeERBYZfeWq3y45tU/s320/Acontias.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The legless skink <i>Acontias</i></td></tr>
</tbody></table>
<ul>
<li>Amphisbaenians are extremely specialized burrowing lizards that, like dibamids, look more like worms than reptiles. <i>Bipes</i> may be the most publicly-known genus thanks to the Internet. Amphisbaenians were, for a long time, considered a unique clade of squamates until molecular evidence moved them into the Lacertoids (along with gymnophthalmids). Lacertoids are what you probably imagine when you think of a generic lizard that isn't a gecko, iguana, or chameleon.</li>
</ul>
<div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWvN4R0_qLQpNHFnma5up9FJ2awyf5l9h1vaZEG6m_rwMuDkI_PxqZTfGpaIVAJoWV-1AkYzmGFiIOkIBM2b2nZvR0eXow3_C4Y7f4a9-N_NWhQeYFeI9znrxOnkTfyYecKinNSkco9Fc/s1600/Amphisbaena.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="312" data-original-width="468" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWvN4R0_qLQpNHFnma5up9FJ2awyf5l9h1vaZEG6m_rwMuDkI_PxqZTfGpaIVAJoWV-1AkYzmGFiIOkIBM2b2nZvR0eXow3_C4Y7f4a9-N_NWhQeYFeI9znrxOnkTfyYecKinNSkco9Fc/s320/Amphisbaena.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An amphisbaenian (<i>Amphisbaena</i>, in fact)</td></tr>
</tbody></table>
So if snakes are just another group of legless lizards, and sets them apart?</div>
<div>
<br /></div>
<div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh75STvhtlivo4_YNZnxyL7q6M5KK_XTZP0bJnzed_iLCmCrc1GhJKGtNrDqnpYkrvXh-ImRKxeNTVoxb4i4o9w7v2b_N9gSpQl6UPmg6v9F6VjqBia8hYMl0tivQ4omvQ6ynbKwbkgaIk/s1600/Diablophis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1332" data-original-width="1124" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh75STvhtlivo4_YNZnxyL7q6M5KK_XTZP0bJnzed_iLCmCrc1GhJKGtNrDqnpYkrvXh-ImRKxeNTVoxb4i4o9w7v2b_N9gSpQl6UPmg6v9F6VjqBia8hYMl0tivQ4omvQ6ynbKwbkgaIk/s320/Diablophis.jpg" width="270" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Jurassic snake <i>Diablophis</i> by Julius Csotonyi</td></tr>
</tbody></table>
Snakes probably evolved in the Mid-to-Late Jurassic from an anguimorph ancestor. This large group includes varanids (monitor lizards) but also Gila monsters, beaded lizards, the extinct marine mosasaurs and a couple other extinct semi-marine groups. Although there is some debate about whether the ancestral snake was a burrower or a swimmer, it should be noted that all other legless lizards listed above are either burrowers or live in the leaf litter of a forest. While there are sea snakes (and sea kraits), they may not represent the original snake.</div>
<div>
<br />
Within varanoids, there's still some debate about exactly who snakes are closest to. The most recent phylogenies that I've seen (and I haven't seen a ton) indicate that snakes are a sister group of mosasaurs. Interestingly, Cope proposed this relationship back in 1869: snakes and mosasaurs were united in a monophyletic Pythonomorpha but that concept fell out of favor until being revived in the last few years.<br />
<br />
Snakes have a fused, transparent eyelid (a bit like geckos), a forked tongue (shared by other anguimorphs), and very reduced skull bones, some of which can dislocate and others that can slide against each-other. Thanks to this, snakes are able to fit through heads around prey items much wider than they are. Compared to other legless lizards, many features of a snake's internal organs are unique compared to non-snake lizards. For example, snakes don't have any lymph nodes. Many snakes are venomous, but venom is more widely distributed in anguimorphs and may actually be more widely distributed in <i>lizards generally</i>, so being venomous, by itself, isn't a feature unique to snakes.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6BxfxfdZqMmLbzLFjCJmyLOmxJPtq_5LTCdk9SlI_gmPDM-lUaeOVw92biR7rBJ0uUyTkZvng506O2RfrYHvzy5zBwRiBs_d6TipDPFIEFC3WZFi0b3rxM1CYSagvI75KgU9eTiJ_C8A/s1600/Titanoboa.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="631" height="152" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6BxfxfdZqMmLbzLFjCJmyLOmxJPtq_5LTCdk9SlI_gmPDM-lUaeOVw92biR7rBJ0uUyTkZvng506O2RfrYHvzy5zBwRiBs_d6TipDPFIEFC3WZFi0b3rxM1CYSagvI75KgU9eTiJ_C8A/s320/Titanoboa.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Titanoboa</i>, a 40-foot long Columbian snake from the Paleocene, by Jason Bourque</td></tr>
</tbody></table>
Snakes are also, obviously, the most successful group of legless lizards by a mile and have adapted to a huge variety of environments and ecological roles.<br />
<br />
Thanks to Gabriel Ugueto for corrections! </div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com4tag:blogger.com,1999:blog-4675540394850433221.post-78775956774599343852018-07-03T12:29:00.001-07:002019-07-05T13:31:37.921-07:00We Can't Have Nice Things<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4-pAXjGmT8H-esGDBcJa0Ahc6QE9lvASUg4ffMbBD_ETOSq56tDZccUcXmhc895L-6-fd59bQozlOT_1RCzJo5Ryr4M8id2oXIzs-epi8Ts-LU27sbikudbgyzNuN5Va40zhpVHvx4e4/s1600/Sinoceratops.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="720" data-original-width="1280" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4-pAXjGmT8H-esGDBcJa0Ahc6QE9lvASUg4ffMbBD_ETOSq56tDZccUcXmhc895L-6-fd59bQozlOT_1RCzJo5Ryr4M8id2oXIzs-epi8Ts-LU27sbikudbgyzNuN5Va40zhpVHvx4e4/s320/Sinoceratops.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Sinoceratops</i> vs. <i>Carnotaurus</i></td></tr>
</tbody></table>
Against all better judgement, I saw <i style="mso-bidi-font-style: normal;">Jurassic World: Fallen Kingdom</i> last night. It was terrible. Until
last night, I’d never seen a movie that didn’t have a single original idea—<i style="mso-bidi-font-style: normal;">Jurassic World 2</i> is a mish-mash of
previous <i style="mso-bidi-font-style: normal;">Jurassic Park/World</i> concepts
thrown into a blender and pureed. While there will be massive spoilers in this
review, I kind of agree with John Conway that <i style="mso-bidi-font-style: normal;">Jurassic World 2</i> is almost incapable of spoilers because you’ve
seen this movie before. In fact, if you’ve seen the trailers, you know
everything that happens; there are no surprises.<br />
<br />
And away we go...<br />
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The movie opens with a small submersible entering the
mosasaur enclosure, years after <i style="mso-bidi-font-style: normal;">Jurassic
World</i> so predictably went awry, to retrieve a bone sample from the <i style="mso-bidi-font-style: normal;">Indominus rex</i> skeleton (see the end of <i style="mso-bidi-font-style: normal;">Jurassic World 1</i>). The pilots are
nervous, obviously afraid of the whale-sized <i style="mso-bidi-font-style: normal;">Mosasaurus</i> that must still be in there, but are comforted in the
knowledge it must be dead after so long.<o:p></o:p></div>
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And that’s true. The mosasaur would be dead from starvation
and thirst (the enclosure had been gated off from the outside ocean). Of course
it’s not, for some reason, and it destroys the sub but not before an <i style="mso-bidi-font-style: normal;">Indominus</i> rib sample is buoyed to the
surface, where some guys in a helicopter retrieve it after tussling with the
resident <i style="mso-bidi-font-style: normal;">Tyrannosaurus</i>. Because the
gate wasn’t shut properly, the mosasaur escapes.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8S1ixfeMtfPTzbe_di08_TLwV089w9-fS4_0-2otlNVR3VdkTVoMZJLlEz5WHAmKVLFpcMWtQ6i402bcE8wXx3VxkUg_8Sdgxk0K75JYYNsuGlAn-_AjrG5l_WFzgEW6_k94UTdnjDWM/s1600/Indominus+Skeleton.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="579" data-original-width="1400" height="132" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8S1ixfeMtfPTzbe_di08_TLwV089w9-fS4_0-2otlNVR3VdkTVoMZJLlEz5WHAmKVLFpcMWtQ6i402bcE8wXx3VxkUg_8Sdgxk0K75JYYNsuGlAn-_AjrG5l_WFzgEW6_k94UTdnjDWM/s320/Indominus+Skeleton.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Seems like there would be easier ways to do this.</td></tr>
</tbody></table>
Meanwhile, Bryce Dallas Howard’s Claire is trying to drum up
political support for a dinosaur rescue operation. Turns out John Hammond built
his park on an active volcano, which totally checks out, and it’s set to blow
at any second. Jeff Goldblum returns for a two-minute Ian Malcolm cameo in
which he argues in front of a congressional subcommittee that, you know, maybe
that’s for the best.</div>
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Just when all hope seems lost, Claire gets a call from
Zefram Cochrane—I mean the pig farmer—I mean <i style="mso-bidi-font-style: normal;">Benjamin Lockwood</i>, an old man who was apparently John Hammond’s
original business partner. Lockwood also wants to save the dinosaurs, and he’s
arranged for them to be shipped to a new island (not just Site B?) that’s not,
at this time, geologically active, where they’ll be left alone, free of human
intervention. Lockwood then turns Claire over to his obviously-evil assistant
Eli Mills, who says they need Claire’s handprint to turn on the island’s
tracking system so they can find all those dinosaurs. Mills also presses upon
Claire that it’s extremely important that they save Blue, the heroic <i style="mso-bidi-font-style: normal;">Deinonychus</i> from the last movie, because
she’s apparently the second-most intelligent creature on the planet.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnb6FMpxSrQVANo0wLC9YdTLmwjxbjVO2jyh5ErTGYYhkfs74u9wvQNssJyWpH6FCa1Uu50tmyP4QrzVLwQ-kPG9ifiHdEHeYXcQLE9rKQMQSBRDCGDouBfCrlHfVOH4mAaPxCRFQDWyk/s1600/Mills.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="713" data-original-width="1600" height="142" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnb6FMpxSrQVANo0wLC9YdTLmwjxbjVO2jyh5ErTGYYhkfs74u9wvQNssJyWpH6FCa1Uu50tmyP4QrzVLwQ-kPG9ifiHdEHeYXcQLE9rKQMQSBRDCGDouBfCrlHfVOH4mAaPxCRFQDWyk/s320/Mills.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Would devil horns be too obvious?"</td></tr>
</tbody></table>
This is the part where I started to wonder why they needed
to save <i style="mso-bidi-font-style: normal;">any </i>of these dinosaurs,
including Blue, because as the last movie made clear, Henry Wu saved all his
research and samples and whatever else once things went south and <i style="mso-bidi-font-style: normal;">he can just make new dinosaurs, including
Blue</i>. But you know what? Fine, whatever.</div>
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Claire goes out to try and convince Chris Pratt’s Starlord
to help her find and rescue Blue. He’s living in a van on a scenic cliff,
building a house because he’s apparently turned into Ron Swanson. He and Claire
broke up for reasons that are never entirely clear but sure, he’ll come along.
Claire also drags along her “dinosaur veterinarian,” Zia, and her nerdy
computer guy, Franklin (I had to look these names up). Within absolutely no
time, they’ve touched down on Isla Nublar, which is in the process of violently
exploding. Our heroes meet Leland Stottlemeyer, who got into the mercenary gig
after retiring from the San Francisco police force. No, wait, it’s just Ted
Levine playing resident bad guy Ken Wheatley, and he’s already been rounding up
dinosaurs and putting them on a barge by the time Claire & Co. arrive.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiayo8ycjxtiZqH-taxxGtdidbsvEPnepAbYkD0pDqqJT3yyuEdCfMXGDUfY381TGXoIh8Z7ZBd7Q1YJjUkaa5HtlGDiKsVh3S4LiinOIGlLpMI6BlJHSHDyH7xB5djjQd5lvovG3CHQzg/s1600/Blue.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="540" data-original-width="960" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiayo8ycjxtiZqH-taxxGtdidbsvEPnepAbYkD0pDqqJT3yyuEdCfMXGDUfY381TGXoIh8Z7ZBd7Q1YJjUkaa5HtlGDiKsVh3S4LiinOIGlLpMI6BlJHSHDyH7xB5djjQd5lvovG3CHQzg/s320/Blue.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Starlord playing with a rubbery baby raptor</td></tr>
</tbody></table>
About a minute later, <i style="mso-bidi-font-style: normal;">Jurassic
World 2</i> drops its first direct homage to <i style="mso-bidi-font-style: normal;">Jurassic Park</i>: a lone <i style="mso-bidi-font-style: normal;">Brachiosaurus</i>
strolling across the ruins of the visitor center, right in front of the humans.
It’s the first dinosaur that Zia and Franklin have seen, so the scene is meant
to be awe-inspiring, but it’s not, because of course <i style="mso-bidi-font-style: normal;">Jurassic World 2</i> doesn’t have the patience to set up the scene like
Spielberg set up his <i style="mso-bidi-font-style: normal;">Brachiosaurus</i>
reveal in <i style="mso-bidi-font-style: normal;">Jurassic Park</i>. Then,
happily checking that particular box, <i style="mso-bidi-font-style: normal;">Jurassic
World 2</i> moves right along to the next checkpoint.</div>
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<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNTshEuMk6LNMD4Su1-g-Os65I6SHqJacIRkMGQse9PiezpT-2ocHSlraALlj-3qKd46TyCReRVzFBrUKWJyNHRzVhahvvVwv0V3d1G3d8KVXYKCFi2X_3pGkSGtOK3W4V5IKW8wo_XRc/s1600/Brachiosaurus.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="251" data-original-width="599" height="134" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNTshEuMk6LNMD4Su1-g-Os65I6SHqJacIRkMGQse9PiezpT-2ocHSlraALlj-3qKd46TyCReRVzFBrUKWJyNHRzVhahvvVwv0V3d1G3d8KVXYKCFi2X_3pGkSGtOK3W4V5IKW8wo_XRc/s320/Brachiosaurus.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"Remember me?"</td></tr>
</tbody></table>
Claire and Franklin activate the park’s tracking system and
they zoom in on Blue, who conveniently happens to be right outside. Starlord
and Wheatley go off to find her while Claire and Franklin stay behind
for…reasons. Starlord immediately finds Blue but as she’s trying to determine
whether or not this movie is worth appearing in, Wheatley’s guys shoot her full
of tranquilizer (and a bullet after she attacks one guy). Wheatley then shoots
Starlord with a dart and leaves him to die, I guess. Meanwhile, Claire and
Franklin get trapped in the visitor center as the volcano starts going off and
liquid hot magma starts pouring into the room.</div>
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<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtMZLsE3L_dWSVPxOzkMwblma9-XzXKOFCEVU-g5Q2PQG3Z_NyWo317BJ9mGsT1XgKnAaJYLvgUWtAyCB0xAp-KASCCp7XIGmzJINg1YT-3_0UPTF7EAguCh2vxlGDNdaKT8FWsEpvqP0/s1600/Blue+vs.+Starlord.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="385" data-original-width="945" height="130" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtMZLsE3L_dWSVPxOzkMwblma9-XzXKOFCEVU-g5Q2PQG3Z_NyWo317BJ9mGsT1XgKnAaJYLvgUWtAyCB0xAp-KASCCp7XIGmzJINg1YT-3_0UPTF7EAguCh2vxlGDNdaKT8FWsEpvqP0/s320/Blue+vs.+Starlord.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"I live in that overturned car."</td></tr>
</tbody></table>
They are then set upon by a…hold on, I have to look this
up…wait, really? Okay, that thing was supposed to be a <i style="mso-bidi-font-style: normal;">Baryonyx</i>. Like every other carnivorous dinosaur in these movies,
the piscivorous <i style="mso-bidi-font-style: normal;">Baryonyx</i> just decided
to attack Claire & Franklin, unprovoked, and nothing will stop it including
liquid-hot magma and a concrete escape hatch that’s too small for it to get
through. Anyway, they of course escape, and meet up with Starlord (who has
miraculously recovered) and they all run away from a pyroclastic flow which is
also, predictably scaring a bunch of dinosaurs. They get behind a big log and lots
of dinosaurs (including <i style="mso-bidi-font-style: normal;">Gallimimus</i>)
jump over or break through it in another direct homage to <i style="mso-bidi-font-style: normal;">Jurassic Park</i>.</div>
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<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYgk0RmDRODQUkcWDpE2lRQMDkh7UP5HPAHibwuh1pBfGozG-_Cz4iZVFQoeC-KrbWL9P2FSP7axCi306oLTIOHdiPfkQ76NTHNCxV7cMPknziUn85UhsdmwAY8Bzg0UVTH5dsQeIt7o0/s1600/Carnotaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="583" data-original-width="1400" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYgk0RmDRODQUkcWDpE2lRQMDkh7UP5HPAHibwuh1pBfGozG-_Cz4iZVFQoeC-KrbWL9P2FSP7axCi306oLTIOHdiPfkQ76NTHNCxV7cMPknziUn85UhsdmwAY8Bzg0UVTH5dsQeIt7o0/s320/Carnotaurus.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Carnotaurus</i>, seconds before being attacked by a more boring theropod.</td></tr>
</tbody></table>
In the middle of this sequence, a <i style="mso-bidi-font-style: normal;">Carnotaurus</i> (my actual favorite dinosaur) decides that eating something
is more pressing than outrunning a volcano and attacks a <i>Si</i><i style="mso-bidi-font-style: normal;">noceratops</i>. Yes, you read that right, <i style="mso-bidi-font-style: normal;">Jurassic World 2</i> features <i>Si</i><i style="mso-bidi-font-style: normal;">noceratops</i>.
This would be more exciting if the character designers hadn’t mistaken the
parietal fenestrae as <i style="mso-bidi-font-style: normal;">actual holes in the
frill of the living animal</i>. Being smarter than its attacker, the <i>Si</i><i style="mso-bidi-font-style: normal;">noceratops</i> is like “BRUH” and runs off
but the <i style="mso-bidi-font-style: normal;">Carnotaurus</i> spies Claire
& Co. As it’s about to attack, the meat-eating bull is put down at the last
second by, yes, the heroic <i style="mso-bidi-font-style: normal;">Tyrannosaurus</i>,
who roars triumphantly and then just…runs off. Doesn’t take the <i style="mso-bidi-font-style: normal;">Carnotaurus</i> with her. Doesn’t eat the
protagonists, just saves their lives for no reason.</div>
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<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYZ4DHNFG9d_lwsNCXE6ynVxV83fcsN9AfiL3TL7_OgmtBqO8O-kqn40ljTCAggq1rzy-SU-gI5TIxbVe6EXV-A2VRY7cWHM1W_5J7GLOPjP_f_-ugzWAi-h2V95oFEgCAZKuAR8Vjcas/s1600/T.rex+gif.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="282" data-original-width="500" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYZ4DHNFG9d_lwsNCXE6ynVxV83fcsN9AfiL3TL7_OgmtBqO8O-kqn40ljTCAggq1rzy-SU-gI5TIxbVe6EXV-A2VRY7cWHM1W_5J7GLOPjP_f_-ugzWAi-h2V95oFEgCAZKuAR8Vjcas/s320/T.rex+gif.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">*heavy, labored sigh*</td></tr>
</tbody></table>
Then there’s a whole thing with a gyrosphere and they wash
up on the beach right next to the barge. Of course our heroes get on the boat
just as the island starts spewing lava from every orifice. There’s a somewhat
touching scene of a <i style="mso-bidi-font-style: normal;">Brachiosaurus</i>—maybe
that same one from before—also trying to get on the boat and is all like “don’t
forget me, guys” before rearing up in another blatant homage to the first <i style="mso-bidi-font-style: normal;">Jurassic Park</i>, and then dying horribly.
Claire is sad.</div>
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Meanwhile, back at the Lockwood estate, Mills is planning to
sell the dinosaurs at auction <i style="mso-bidi-font-style: normal;">that night
in the basement of Lockwood’s mansion for some reason</i>, with Toby Jones’
Gunner Eversol as auctioneer. Couldn’t wait a day. Toby Jones can do no wrong,
and he’s clearly enjoying himself in this role. His wig is also fabulous. We
also discover that the mansion contains a full genetic laboratory downstairs.
We also learn more about Lockwood’s granddaughter, Maisie. <o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCy4optwG64XYDznpmA1vO9QXkiajxsDn7RGVbnMrLdYRKQi5hm8gpaWdrLp2Jy8lIvMNsrthSipPJldTgHfEDYVIDQ8Zh8sx9-Y98uMJWSwkH5zQSyuSxEPpZt29ZKhuKoL4kqIZrVrE/s1600/Dino+Auction.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="750" data-original-width="1500" height="160" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCy4optwG64XYDznpmA1vO9QXkiajxsDn7RGVbnMrLdYRKQi5hm8gpaWdrLp2Jy8lIvMNsrthSipPJldTgHfEDYVIDQ8Zh8sx9-Y98uMJWSwkH5zQSyuSxEPpZt29ZKhuKoL4kqIZrVrE/s320/Dino+Auction.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Here she is...Miss Isla Nublar...</td></tr>
</tbody></table>
Oh, sorry, I didn’t mention that Lockwood has a
granddaughter named Maisie. That will be important—or at least the filmmakers
seem to think so—later on.</div>
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<o:p></o:p></div>
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Claire and Starlord find Zia, who’s been trying to keep Blue
alive. I guess she’s losing blood from being shot and Zia doesn’t want to risk
pulling the bullet out without a blood transfusion. Sure, okay, I’ll buy that.
But hey, there aren’t any other <i style="mso-bidi-font-style: normal;">Deinonychus</i>
on board, or even on the (now lava-covered) island. But hey that’s okay,
because—<o:p></o:p></div>
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<br /></div>
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Dear readers, hold on to your butts.<o:p></o:p></div>
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<br /></div>
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It’s okay because as long as they find another <i style="mso-bidi-font-style: normal;">tetanuran</i> the blood should be “close
enough.” <o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
Yeah.<o:p></o:p></div>
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<br /></div>
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Trevorrow and Derek Connelly, who share writing credits, clearly
learned a new word, “tetanuran,” and proudly wanted Zia to sound like she knew
something about dinosaurs despite having never seen or treated one. “They’re
theropods that have only two or three fingers.” Technically, that’s true. You
get a gold star, Trevorrow. So of course the only other tetanuran theropod they
can find is the <i style="mso-bidi-font-style: normal;">Tyrannosaurus</i>, who
shrank considerably since pinning that <i style="mso-bidi-font-style: normal;">Carnotaurus</i>
earlier so that she could fit in a shipping container.<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZwitq0ind69YiPeVWBRj5ANcZaUoW4qzbKrvTnOynHrOKTXcJ6DkwHTh6KvbzcxNSYpasVKPGnYMdIWR6D16UK03Lp5ItnLTW6M0fQpr7dOtlmgStgefQrgTBki4wNYvYXpqMOI5fBPw/s1600/T.rex+blood.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZwitq0ind69YiPeVWBRj5ANcZaUoW4qzbKrvTnOynHrOKTXcJ6DkwHTh6KvbzcxNSYpasVKPGnYMdIWR6D16UK03Lp5ItnLTW6M0fQpr7dOtlmgStgefQrgTBki4wNYvYXpqMOI5fBPw/s320/T.rex+blood.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"I mean they all have frog DNA anyway, right?"</td></tr>
</tbody></table>
Just so we’re clear, this would be like a person needing a
blood transfusion and the doctor saying “you know, we don’t have any blood of
your type, or even from other people, but as long as we use <i style="mso-bidi-font-style: normal;">simiiforme</i> blood, that’s close enough.”
Monkey blood, basically. They’re giving a <i style="mso-bidi-font-style: normal;">Deinonychus</i>
the equivalent of monkey blood. And of course it works.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Anyway.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Good lord. Where’s that whiskey?<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
All of the animals arrive at the mansion just in time for
Henry Wu to start lecturing Mills about their new <i style="mso-bidi-font-style: normal;">Indoraptor</i>, which is like a fun-size <i style="mso-bidi-font-style: normal;">Indominus</i> but with raptor claws and (apparently) mommy issues. It’s
kept in seclusion in a dark cage at the end of a hall, which seems fine. At
least the <i style="mso-bidi-font-style: normal;">Indominus</i> had a whole
jungle enclosure. Claire and Starlord are caught and, instead of being shot
immediately, are put in an animal cell. The auction begins, with, of course,
Russian arms dealers buying up the dinosaurs. One of the dinosaurs goes for
$10M, which may seem like a lot until you remember that FMNH PR 2081 (Sue) sold
at auction for $8.4M. You’d think living dinosaurs would sell for significantly
more. <o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgL6K87sBGWnwurjAnBRvsE81xdnPIlncU1OTcGKOOtNbyKZ4GFWKQ35HPsdQn823P3QFDesrVPQZlzsswMDSAB0Y9QdBrVrSZ0jQ_zJIDQE5-wqtkybMKBQIAjXq1QiIN00Y5Yhn0Fz6c/s1600/Sue.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="533" data-original-width="1200" height="142" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgL6K87sBGWnwurjAnBRvsE81xdnPIlncU1OTcGKOOtNbyKZ4GFWKQ35HPsdQn823P3QFDesrVPQZlzsswMDSAB0Y9QdBrVrSZ0jQ_zJIDQE5-wqtkybMKBQIAjXq1QiIN00Y5Yhn0Fz6c/s320/Sue.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cheap!</td></tr>
</tbody></table>
There’s literally a shot, somewhere during this sequence,
where Mills is just watching his laptop screen as a dollar figure trends
upward, representing the millions he’s making, in case his motivations prior to
this point were unclear. Oh, did I mention he killed Lockwood? He kills
Lockwood by suffocating him with a pillow after Lockwood finds out what Mills
is doing with his dinosaurs.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Eventually, the <i style="mso-bidi-font-style: normal;">Indoraptor</i>
is wheeled out. It’s essentially a jet-black, gigantic raptor with a yellow
racing stripe down its side. It has the dumb quills, dorsal armor, and
misshapen fish teeth that <i style="mso-bidi-font-style: normal;">Indominus</i>
had, but it also has oversized claws, four fingers, and regularly reverts to
quadrupedality. Toby Jones brags that it’s the most dangerous animal in the
world. BUT JUST THEN—<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Wait, let’s back up a second. Claire and Starlord are having
a heart-to-heart in their empty cell about who’s fault this is (look, you’re
both idiots) when the latter realizes there’s a <i style="mso-bidi-font-style: normal;">Stygimoloch</i> in the next cell. He goads the spunky little bonehead
into breaking through the brick wall separating them, and then breaking out of
the locked cell door. Starlord then sets the <i style="mso-bidi-font-style: normal;">Stygimoloch</i> loose on the auctioneers in what’s honestly the
funniest scene in the film. I mean, they already kind of did this in <i style="mso-bidi-font-style: normal;">The Lost World</i> but who’s counting?<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlGVMZkaoqyT0tgo5tm2KPhcxI-GIfg0_ZXxOIIbPtvnBgt9Axs1Qj_RFdZsbDHAELzhblb8WJmXvqUjNRfu4UM2_D4zvO4pJRqRPSTRIjvgpIafmPfb0pd5qXDxfSuRO3g0DArSEwePc/s1600/Stygimoloch.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="534" data-original-width="950" height="179" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlGVMZkaoqyT0tgo5tm2KPhcxI-GIfg0_ZXxOIIbPtvnBgt9Axs1Qj_RFdZsbDHAELzhblb8WJmXvqUjNRfu4UM2_D4zvO4pJRqRPSTRIjvgpIafmPfb0pd5qXDxfSuRO3g0DArSEwePc/s320/Stygimoloch.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Stygimoloch</i> is the only one getting anything done around here.</td></tr>
</tbody></table>
Oh, right, ALSO at the same time, Zia and Franklin free
Blue, who has recovered completely from being shot in the leg, being tranquilized,
and getting a blood transfusion and she goes hog-wild on some mean-looking
mercenaries but also accidentally causes a cyanide gas leak.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Where were we? Oh, right, so the auction has essentially
disbanded because of the rogue subadult <i style="mso-bidi-font-style: normal;">Pachycephalosaurus</i>
and Wheatley—remember him?—wanders in asking where his “bonus” is. There’s
nobody around, but the <i style="mso-bidi-font-style: normal;">Indoraptor</i> is
just sitting there in its cage in the center of the room and Wheatley decides
to take one of its teeth as a trophy.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
I don’t know why. He did this with a few of the dinosaurs on
the island, too.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
I’m not going to tell you what happens next because you
already know. They didn’t even have to film the scene. They could’ve just cut
between Ted Levine looking at the <i style="mso-bidi-font-style: normal;">Indoraptor</i>
and the <i style="mso-bidi-font-style: normal;">Indoraptor</i>, now free,
attacking Toby Jones. Our brains would have easily filled in the blank.<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcWDGhJpiLVwCC7V9PxmOeLQrE3R-Tr27meV2rqpt1Xo_QHIdXE-dv15-0XgSWWWi0OjO4mp1tmJF0Og4HV541IdiGtbgCLrGo9bSI4u8d_DMRMqZqqZZKKnanlvBwX-poFB7TjdknixM/s1600/Indoraptor+2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="559" data-original-width="1200" height="149" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcWDGhJpiLVwCC7V9PxmOeLQrE3R-Tr27meV2rqpt1Xo_QHIdXE-dv15-0XgSWWWi0OjO4mp1tmJF0Og4HV541IdiGtbgCLrGo9bSI4u8d_DMRMqZqqZZKKnanlvBwX-poFB7TjdknixM/s320/Indoraptor+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Indoraptor</i> stalking the heroes for some reason.</td></tr>
</tbody></table>
So now the <i style="mso-bidi-font-style: normal;">Indoraptor</i>
is looking for things to kill. It somehow gets upstairs and starts stalking
Claire, Starlord, and Maisie through Lockwood’s mansion. I say “stalking” but
what I really mean is “chasing them for no reason whatsoever and not letting
anything stop it” because that’s what predatory dinosaurs in these movies do,
right? So anyway, after a brief scuffle in which Maisie runs to her bedroom,
the <i style="mso-bidi-font-style: normal;">Indoraptor</i> somehow gets out of
the building and crawls (I’m saying crawls because that’s literally what it’s
doing) to the other side, right where Maisie’s room happens to be, and reaches
down—it is upside-down at this point—to unlatch her window—again, the animal
does this while upside-down—and walks right in. Just as it’s about to attack
Maisie—for no reason whatsoever—Starlord pops in, tries to tranquilize it but
fails, and is then YES YOU GUESSED IT, IS SAVED BY BLUE, THE HEROIC <i>DEINONYCHUS</i>.</div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi77vizgw1psUqBrfmxJVRTmcPt9XLvXNxwK-UU4A2wgLbZgH0FZT1CjQ0y6OVPIZa8L_2f76n0qEcsxV3W6Gwtc2Akoh9eQwz_4VzENmaankACXw8Z5WKtBENrFkD7mc6-ndXt95b9aew/s1600/Blue+vs.+Indoraptor.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi77vizgw1psUqBrfmxJVRTmcPt9XLvXNxwK-UU4A2wgLbZgH0FZT1CjQ0y6OVPIZa8L_2f76n0qEcsxV3W6Gwtc2Akoh9eQwz_4VzENmaankACXw8Z5WKtBENrFkD7mc6-ndXt95b9aew/s320/Blue+vs.+Indoraptor.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This is every Marvel movie: the hero vs. an evil version of him/herself.</td></tr>
</tbody></table>
Starlord and Maisie escape to the rooftop in the commotion
but Blue is thrown out a window (I think) as the <i style="mso-bidi-font-style: normal;">Indoraptor</i> pursues its human prey across a glass rooftop, which is
shining down over Lockwood’s dinosaur skeleton room (he has a dinosaur skeleton
room).* With some help from Claire, they manage to get the <i style="mso-bidi-font-style: normal;">Indoraptor</i> to break through the glass BUT OF COURSE IT HANGS ON AND
PULLS ITSELF BACK UP OH NO and then YES, YOU GUESSED IT AGAIN, BLUE MAGICALLY
APPEARS AGAIN, JUMPS ON ITS BACK AND THE TWO PLUMMET DOWN INTO THE SKELETON
ROOM WHERE THE <i style="mso-bidi-font-style: normal;">INDORAPTOR</i> IS SKEWERED
ON TWO <i style="mso-bidi-font-style: normal;">TRICERATOPS</i> HORNS.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilVU2o5QQrRAhhp3BwI6cqqWUUugGPqtJ3GhztHKJeTvEmkC8KdDvgLgevdYoDy8qxz2f4Rz99HyZEIydgahbMfnILUCx-jBnhgzlTgKJEtEnghBx7z-CrDCmQ7peHWUicBbZ6VDBw9tI/s1600/Indoraptor.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="540" data-original-width="960" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilVU2o5QQrRAhhp3BwI6cqqWUUugGPqtJ3GhztHKJeTvEmkC8KdDvgLgevdYoDy8qxz2f4Rz99HyZEIydgahbMfnILUCx-jBnhgzlTgKJEtEnghBx7z-CrDCmQ7peHWUicBbZ6VDBw9tI/s320/Indoraptor.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"You're next!"</td></tr>
</tbody></table>
Meanwhile—yes, there’s more—all of the unsold dinosaurs are
succumbing to cyanide poisoning. Claire runs down to the control room, opens
the cages, and the dinosaurs all stumble around, bumping into each other, but
can’t actually leave because the bay doors are closed.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So they’re still dying. Good job, Claire.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Our plucky heroine then has a sudden and uncharacteristic
moment of clarity, thinking that maybe we <i style="mso-bidi-font-style: normal;">should</i>
let these things die because they really <i style="mso-bidi-font-style: normal;">do</i>
kill a lot of people. She does not open the bay doors, and she and Starlord
watch pensively as the dinosaurs suffocate. The end.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
No, of course not. Maisie opens the bay doors because
somewhere along the line she realized that she’s a clone of Lockwood’s daughter
and dammit, if she’s a clone and…hasn’t been killed (I guess), these cloned
dinosaurs should ALSO be able to live.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
That narrative thread and all its implications vanishes
immediately. There is absolutely no payoff to the fact that Lockwood is cloning
people in his basement. It’s a good thing he decided to clone her, because
otherwise nobody would have opened those bay doors.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So anyway, Mills has chosen this moment to flee, and while
Henry Wu’s people are busy reenacting his escape from the last movie, Mills is
put in charge of the <i style="mso-bidi-font-style: normal;">Indominus</i> rib
fragment, because I guess Wu doesn’t have its DNA blueprints already? But if
that’s true, how did he create the <i style="mso-bidi-font-style: normal;">Indoraptor</i>?
You know what, trying to make sense of this movie is a fool’s errand. Mills
hides under his car while all of these freed dinosaurs run into the woods but
hey you know who hasn’t done a heroic thing for awhile?<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
YES, KIDS, THE <i style="mso-bidi-font-style: normal;">TYRANNOSAURUS</i>
MATERIALIZES AND GOBBLES MILLS DOWN WHILE SIMULTANEOUSLY REBUFFING A SECOND <i style="mso-bidi-font-style: normal;">CARNOTAURUS</i>. THE <i style="mso-bidi-font-style: normal;">TYRANNOSAURUS</i> THEN ADOPTS THE EXACT SAME POSE AS IT DID AT THE END
OF <i style="mso-bidi-font-style: normal;">JURASSIC PARK</i> AND ROARS
VICTORIOUSLY before running off into the woods with its cloned friends.
Starlord tells Blue that she did good and he’ll take her somewhere safe but
she’s all like NAW DOG I’M OUT and also runs off.<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDPFydkVcnTy_igbt_8Uzg7WTTgdsdmJ0n8l0U-5zQWoy4t5YrkEw3Vl5mNS7eSknVuvdQBUBU11vWYXMe8P7MUObW3JbJvi12Bi0SgOZTV0-BBKJ33f0bS9hiIIL5hvr1-818m1M8Fok/s1600/T.rex.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="414" data-original-width="759" height="174" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDPFydkVcnTy_igbt_8Uzg7WTTgdsdmJ0n8l0U-5zQWoy4t5YrkEw3Vl5mNS7eSknVuvdQBUBU11vWYXMe8P7MUObW3JbJvi12Bi0SgOZTV0-BBKJ33f0bS9hiIIL5hvr1-818m1M8Fok/s320/T.rex.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Edit out the flag and this is how <i>Jurassic World 2</i> ends.</td></tr>
</tbody></table>
Then there’s a montage of the bought-and-sold dinosaurs
being driven to their new homes, oh and also Henry Wu still has a bunch of test
tubes filled with neon-colored stuff so, you know, whatever. Ian Malcolm
continues talking about how humans have fucked it all up and we’re going to
cause our own extinction because two dozen dinosaurs are still out there. The
giant <i style="mso-bidi-font-style: normal;">Mosasaurus</i> shows up near
surfers, eager to appear in the inevitable sequel to <i style="mso-bidi-font-style: normal;">The Meg</i>. The <i style="mso-bidi-font-style: normal;">Tyrannosaurus</i>
breaks into a zoo and roars at a lion in order to signify…something. Blue runs
around a rocky outcropping and notices a residential neighborhood nearby. <i style="mso-bidi-font-style: normal;">THE WORLD WILL NEVER BE THE SAME</i>.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaEDjIisfFmZs5DJCvHuiLkMuccHl4YETm6SeqIA_lESDFUpOk5jZOl5IEeaxmTQaTr17ygawJicOk6lhwEBjTsPocrES0si4_2Puh1aEKkJs6CvU5KQ905dxhXHpHygwCLiEZwpUIMAk/s1600/Rex+vs.+Lion.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="900" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaEDjIisfFmZs5DJCvHuiLkMuccHl4YETm6SeqIA_lESDFUpOk5jZOl5IEeaxmTQaTr17ygawJicOk6lhwEBjTsPocrES0si4_2Puh1aEKkJs6CvU5KQ905dxhXHpHygwCLiEZwpUIMAk/s320/Rex+vs.+Lion.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">"I AM THE CAPTAIN NOW"</td></tr>
</tbody></table>
There’s also a post-credits scene that’s 10 seconds long
where a few <i style="mso-bidi-font-style: normal;">Pteranodon</i> are flying
around Las Vegas in case those last three images didn’t get the point across.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This was one of the worst movies I’ve seen in a long time.
Barring all the ridiculous dinosaur nonsense, no part of the film made any
sense from a story perspective. Why would Mills go to any of this trouble when
he can just tell Henry Wu to make new dinosaurs? Henry Wu is clearly already
making dinosaurs, and it’s not like you can’t sell those dinosaurs to Russian
mobsters ahead of time. Lockwood has no actual role. He didn’t need to be in
this movie. It could’ve just been Mills from the get-go who gives Claire the
assignment. Maisie being a clone literally had no impact on the overall story
except for her reasoning behind opening the bay doors and saving the dinosaurs.
Claire could’ve done that. Starlord could’ve done that. BLUE could’ve done
that. <o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So now there are dinosaurs out in the wild. So what? Unless
they’re all miraculously parthenogenetic, the threat of a dinosaur takeover is
less than zero. These animals are going to be shot, hit by trucks, succumb to
unfamiliar diseases, or die of old age <i style="mso-bidi-font-style: normal;">and
then there won’t be any more dinosaurs</i>. The mosasaur is only a problem for
as long as people decide not to shoot a torpedo at it. The dinosaurs who were
sold to dictators and arms dealers have an even lower life expectancy. And has
everybody forgotten about Isla Sorna? You know, Site B from <i style="mso-bidi-font-style: normal;">The Lost World</i> and <i style="mso-bidi-font-style: normal;">Jurassic Park III</i>? If Mills wanted more dinosaurs, there’s a whole
island filled with them that is NOT, at least to my knowledge, exploding.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The dinosaurs themselves exist in a weird uncanny valley.
Most of them are shiny—this is especially apparent on the <i style="mso-bidi-font-style: normal;">Indoraptor</i>. They look almost moist. Almost every herbivorous
dinosaur, no matter how bulky, is shown galloping away from that pyroclastic
flow. It looks silly. There are a few new dinosaurs but only three of them (<i style="mso-bidi-font-style: normal;">Carnotaurus, Stygimoloch </i>and, if I’m
being generous, <i style="mso-bidi-font-style: normal;">Allosaurus</i>) looks
anything like their IRL counterparts. As I said before, the <i>Si</i><i style="mso-bidi-font-style: normal;">noceratops</i> has actual holes in its
actual frill. I’m not convinced the character designers were looking at the
right animal when they were designing <i style="mso-bidi-font-style: normal;">Baryonyx</i>.
Blue continues to be a cartoonish, rubbery mess of a character who’s just doing
way too much all the time in exaggerated ways. Like <i style="mso-bidi-font-style: normal;">Indominus</i> before it, the <i style="mso-bidi-font-style: normal;">Indoraptor</i>
is incredibly dull, as if Trevorrow told the character designers “make a <i style="mso-bidi-font-style: normal;">Velociraptor</i> on steroids.” And, in
another bit of intellectual bankruptcy, the <i style="mso-bidi-font-style: normal;">Indoraptor</i>
of course taps its claw impatiently.<o:p></o:p></div>
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I keep calling Chris Pratt’s character “Starlord” instead of
“Owen” because there’s virtually no difference between the two characters. The
villains, especially Mills, are so stereotypically evil that I’m surprised
nobody gave Rafe Spall a Snidely Whiplash mustache with which to twirl. Colin
Trevorrow is no Steven Spielberg, although he seems to think (based on
interviews I’ve read) that these <i style="mso-bidi-font-style: normal;">Jurassic
World</i> films really are emulating <i style="mso-bidi-font-style: normal;">Jurassic
Park</i>. They are not, and it’s clear that, in wedging in so very many direct
references to its predecessor, Trevorrow's films don’t understand what made that
movie great or memorable. Using the final <i style="mso-bidi-font-style: normal;">Tyrannosaurus</i>
turn-and-roar is not a touching homage—it’s evidence that (1) you don’t have
any original ideas; and (2) you’re acknowledging that <i style="mso-bidi-font-style: normal;">Jurassic Park</i> is a better movie.<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3yQwFaoCgdjqeIvRFXdwYUx1YeHSyLoVE7X-EvXvZ8MaH2st31xBmU6TV2Lam3SfWL-ESC7A32b4AYTfoWFcp5l6UbuKaiU7P5WxgWL-aibF2RZck89MqhXGCghl_8dQtgeEbikgrcuc/s1600/Trike+Poop.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="693" data-original-width="1280" height="173" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3yQwFaoCgdjqeIvRFXdwYUx1YeHSyLoVE7X-EvXvZ8MaH2st31xBmU6TV2Lam3SfWL-ESC7A32b4AYTfoWFcp5l6UbuKaiU7P5WxgWL-aibF2RZck89MqhXGCghl_8dQtgeEbikgrcuc/s320/Trike+Poop.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dr. Ellie Sattler digs through <i>Jurassic World 2</i>.</td></tr>
</tbody></table>
So just rewatch that instead of seeing this pile of <i>Triceratops</i> droppings. And if you do see it, be sure to wash your hands before eating anything.</div>
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*There’s actually a miniature <i style="mso-bidi-font-style: normal;">Concavenator</i>
in there, which is kind of cool.<o:p></o:p></div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com14tag:blogger.com,1999:blog-4675540394850433221.post-12338783061132941352018-06-07T15:04:00.002-07:002018-06-07T15:05:43.938-07:00Faux Theropods<div class="MsoNormal">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy1cbMnorjxrR3jvJsfVAe5FDWFaCEMnNrsTvVKfF2M_ZgDLvvG18qb0Bga0tT6T4_CLIKCaN7aEzqMHv98IfbD_LymLiaAhfysYGq7WfMv078SeLkLcGgLFzF4r_-flGL0KiT0W3d1_k/s1600/Effigia+Skeleton.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="249" data-original-width="798" height="99" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy1cbMnorjxrR3jvJsfVAe5FDWFaCEMnNrsTvVKfF2M_ZgDLvvG18qb0Bga0tT6T4_CLIKCaN7aEzqMHv98IfbD_LymLiaAhfysYGq7WfMv078SeLkLcGgLFzF4r_-flGL0KiT0W3d1_k/s320/Effigia+Skeleton.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skeleton of <i>Effigia</i></td></tr>
</tbody></table>
Bit of a shorter post this month, as I'm prepping a photo-heavy review of the Creative Beast raptor toys that I just received. This month I’ve decided to tackle one of my absolute
favorite groups of Triassic weirdos: shuvosaurids! They are a fairly obscure clade outside of paleo circles, consisting of only three (used to be four) named
genera but shuvosaurids should be poster children for the concept of convergent
evolution. These things are pseudosuchian <i style="mso-bidi-font-style: normal;">theropod
mimics</i>, and not just theropods but <i style="mso-bidi-font-style: normal;">ornithomimosaurs</i>.
Ostrich dinosaurs in the Triassic...but suchians!<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTI8Ia_P3BB8ZWxR-RE_q8NAwYdtcrnNouCoDYMsxKm5iJkuGbel92FY63VeRtLro-ZbzHc4gq2DwiZp5M6Bk8lwUOKl6FWmaI0zV1Mc2Qg-b_Qnk-s5Bq0wvAWllWTdBkf3yulFh1xeE/s1600/Shuvosaurus+Skull.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="332" data-original-width="532" height="199" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTI8Ia_P3BB8ZWxR-RE_q8NAwYdtcrnNouCoDYMsxKm5iJkuGbel92FY63VeRtLro-ZbzHc4gq2DwiZp5M6Bk8lwUOKl6FWmaI0zV1Mc2Qg-b_Qnk-s5Bq0wvAWllWTdBkf3yulFh1xeE/s320/Shuvosaurus+Skull.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The largely complete skull of <i>Shuvosaurus</i></td></tr>
</tbody></table>
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<i style="mso-bidi-font-style: normal;">Shuvosaurus
inexpectatus</i> was the original shuvosaurid (as you might expect), a Late
Triassic taxon described in by Chatterjee in 1993. While the Texas holotype
(TTU-P-9280) consists of most of the skull, paratypes (TTU-P-9281 & 9282)
filled in some details. He referred some associated fragmentary bits—a
vertebra, fragment of scapula, and tibia—to <i style="mso-bidi-font-style: normal;">Shuvosaurus</i>
as well, but it’s not clear whether those bones belong with the skull, and have
been ignored by subsequent authors. The skull is small, probably from a
juvenile, and toothless. Rather incredibly, Chatterjee referred it to the
Ornithomimosauria in a new basal family, the Shuvosauridae. This doesn’t just
pull ornithomimosaurs back to the Late Triassic but every other theropod
lineage that branched off prior to ostrich dinosaurs (coelurosaurs, basically).
Of course, this referral was met with some degree of disbelief from other
workers.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_tE-7yGIFGBbW61MGyG5TSoFsrm4nMXBgwc8rX43KNjbpSUiDOBNszGy7Ukte-Wz-STitjd3uPzCVqsONaLSVAW0-l_v0KvsK2Y_nW8TfYBlV6F69QpQ_KhWqPmLMdNq4B4qSdQWjmKc/s1600/Chatterjeea+Holotype.bmp" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="519" data-original-width="1600" height="103" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_tE-7yGIFGBbW61MGyG5TSoFsrm4nMXBgwc8rX43KNjbpSUiDOBNszGy7Ukte-Wz-STitjd3uPzCVqsONaLSVAW0-l_v0KvsK2Y_nW8TfYBlV6F69QpQ_KhWqPmLMdNq4B4qSdQWjmKc/s320/Chatterjeea+Holotype.bmp" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The holotype of <i>Chatterjeea</i></td></tr>
</tbody></table>
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The first blow came in 1995, when Long & Murry described
both <i>Chatterjeea elegans</i> and its new
family, the Chatterjeea (sigh). The holotype, from the same area as <i>Shuvosaurus</i>, is an incomplete but very
informative postcranial skeleton. Additional fragmentary material from Arizona
and New Mexico was referred to this new genus. In short, there’s apparently a lot
of <i>Chatterjeea</i> material. Despite
being bipedal and gracile, the authors refer their new taxon to the
Poposauridae. They also comment on Chatterjee’s <i>Shuvosaurus</i>, expressing doubt that <i>Shuvosaurus</i> is a theropod at all, much less an ostrich dinosaur,
instead of a “highly derived pre-dinosaurian archosaur.” Further, they suspect
that the holotype skeleton of <i>Chatterjeea</i>
may belong with the holotype skull of <i>Shuvosaurus</i>.
Although they admit that the two cannot be synonymized with certainty pending
the discovery of overlapping material, that possibility can’t be ignored. If
they are from the same species, then <i>Chatterjeea</i>
becomes a junior synonym of <i>Shuvosaurus</i>.</div>
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Despite <i style="mso-bidi-font-style: normal;">Chatterjeea</i>’s
poposaurid affinities, Long & Murry admit that “If it were not for a number
of similarities in common with the popposaurids and the presence of a
crurotarsal [ankle] joint, the chatterjeeids might be confused as a sister
group to the Dinosauriformes.” Foreshadowing!<o:p></o:p></div>
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Almost on cue, Rauhut (1995), in his redescription of the
skull of <i style="mso-bidi-font-style: normal;">Shuvosaurus</i>, refers the
animal to Theropoda, but does not endorse an ornithomimosaur affiliation. After
going over why <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> can’t be
an ornithomimosaur, coelurosaur, or tetanurine, he settles on a “basal
theropod” position, noting that “more information is needed to assess its
phylogenetic position.” Rauhut does not comment on the possibility that <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> may be synonymous with <i style="mso-bidi-font-style: normal;">Chatterjeea</i> and probably considers them
to be very different animals.<o:p></o:p></div>
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Onward and upward: brief mentions of <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> in Murry & Long (1997) and Osmolska (1997) further
question its theropod affinity. Hunt et al. (1998) supported the synonymy of <i style="mso-bidi-font-style: normal;">Shuvosaurus </i>and <i style="mso-bidi-font-style: normal;">Chatterjeea.</i><o:p></o:p></div>
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<i style="mso-bidi-font-style: normal;"><br /></i>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgADBSwZLPFuhyAIfpEsTHvwb_LL5oERLPBQbDwKTF4jEy6Ysmk3KTu8RNf48Xy5U0h9-cif_L9V5BA4lmk0ELca2RIYMcRDsGY-wMzJ2i6Q3Ae_DY692RFlfRS3Y06C8PrllhYT3z2bbk/s1600/Effigia+Skull.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="697" data-original-width="833" height="267" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgADBSwZLPFuhyAIfpEsTHvwb_LL5oERLPBQbDwKTF4jEy6Ysmk3KTu8RNf48Xy5U0h9-cif_L9V5BA4lmk0ELca2RIYMcRDsGY-wMzJ2i6Q3Ae_DY692RFlfRS3Y06C8PrllhYT3z2bbk/s320/Effigia+Skull.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skull of <i>Effigia okeeffeae</i></td></tr>
</tbody></table>
Then, in 2006, <i style="mso-bidi-font-style: normal;">Effigia
okeeffeae</i> happened when a nearly complete skull and skeleton was described
by Nesbitt & Norell (2006). Here was a relatively small-bodied, bipedal,
toothless, puny-armed pseudosuchian complete with crurotarsal ankle that also,
finally, illuminated the murky identity of <i style="mso-bidi-font-style: normal;">Shuvosaurus</i>.
Nesbitt & Norell further endorse the idea that the <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> skull belongs to the <i style="mso-bidi-font-style: normal;">Chatterjeea</i> skeleton, and so sink former as a junior synonym of the
latter. The authors pull a third fragmentary taxon, <i style="mso-bidi-font-style: normal;">Sillosuchus longicervix</i> from Argentina (Alcober & Parrish, 1997), into the
Shuvosauridae as well, demonstrating that these animals had a much wider
distribution than just the southwestern United States.</div>
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<o:p></o:p></div>
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The very next year, Nesbitt (2007) published a complete
description of <i style="mso-bidi-font-style: normal;">Effigia</i>. This
impressive monograph details its osteology, tests its growth (via histology),
tests its relationships with other pseudosuchians, and goes over its impressive
list of convergences with dinosaurs. Surprisingly, shuvosaurids form a sister
group relationship with the larger, sail-backed <i style="mso-bidi-font-style: normal;">Lotosaurus</i> (who is also toothless) and <i style="mso-bidi-font-style: normal;">Arizonasaurus</i>.* Finally, Nesbitt et al. (2007), in their
comprehensive review of North American Triassic dinosaurs, concluded that the
vertebrae of alleged Triassic theropod <i style="mso-bidi-font-style: normal;">Gojirasaurus
quayi</i> (Carpenter, 1997) cannot be differentiated from <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> while its pubis and tibia cannot be differentiated from
<i style="mso-bidi-font-style: normal;">Coelophysis</i>.<o:p></o:p></div>
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCeS7co3HERMSCJ8Fnk0F-H2h-z65DRAxFJXtq3dBSpV-D454xjm2jZ8tQ03dxWNcGJaeAvLDBmukkx7zBDH01WOQUv-ETSnnQq_nfn-fCUKXLNOqDuLz6EqGBcmvU1bRw7KjKtkeqYtA/s1600/Effigia+Buell.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="187" data-original-width="600" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCeS7co3HERMSCJ8Fnk0F-H2h-z65DRAxFJXtq3dBSpV-D454xjm2jZ8tQ03dxWNcGJaeAvLDBmukkx7zBDH01WOQUv-ETSnnQq_nfn-fCUKXLNOqDuLz6EqGBcmvU1bRw7KjKtkeqYtA/s400/Effigia+Buell.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Effigia okeefeae</i> by Carl Buell</td></tr>
</tbody></table>
Shuvosaurids present an incredible case of convergent
evolution with theropods. Nesbitt (2007) presents an impressive list, but the
ones I found most interesting were:</div>
<div class="MsoNormal">
</div>
<ul>
<li>No osteoderms, and this also appears to be
the case in the shuvosaurids’ sail-backed sister group including <i style="text-indent: -0.25in;">Arizonasaurus</i><span style="text-indent: -0.25in;"> and </span><i style="text-indent: -0.25in;">Lotosaurus</i><span style="text-indent: -0.25in;">.</span></li>
<li><span style="text-indent: -0.25in;">Strongly reduced forelimb—what could it do with
those tiny hands?</span></li>
<li><span style="text-indent: -0.25in;">Four sacral vertebrae. It’s apparently rare to
find a croc-line archosaur with more than two. Furthermore, in </span><i style="text-indent: -0.25in;">Effigia</i><span style="text-indent: -0.25in;"> and </span><i style="text-indent: -0.25in;">Shuvosaurus</i><span style="text-indent: -0.25in;">, the vertebrae are fused into a rigid rod of bone.</span></li>
<li><span style="text-indent: -0.25in;">An expanded pubic boot, which is very common
among theropods (think </span><i style="text-indent: -0.25in;">Allosaurus</i><span style="text-indent: -0.25in;">).</span></li>
<li><span style="text-indent: -0.25in;">Toothless jaws, which must be exceptionally rare
in pseudosuchians.</span></li>
</ul>
<div class="MsoListParagraphCxSpLast" style="mso-list: l0 level1 lfo1; text-indent: -.25in;">
<o:p></o:p></div>
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<i style="mso-bidi-font-style: normal;">Effigia</i> was a
dog-sized animal, but <i style="mso-bidi-font-style: normal;">Shuvosaurus</i> may
have grown much, much larger based on the vertebrae originally assigned to “<i style="mso-bidi-font-style: normal;">Gojirasaurus</i>.” When it was originally
described, “<i style="mso-bidi-font-style: normal;">Gojirasaurus</i>” was thought
to be as large as <i style="mso-bidi-font-style: normal;">Dilophosaurus</i>! <i style="mso-bidi-font-style: normal;"><o:p></o:p></i></div>
<div class="MsoNormal">
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvKPHPsySq3A4ItnlVulYWvKtIfFP5ISAxUAirGR2KZxXbXwBAAYW10UkyAWU5HxVezleM2lxk9A3D6CGttI6wX_hgbQsrEewD-d-vOPZO3TGHWoYcZwb_WRjIYpHDS6PyM6TS_eS7-qA/s1600/Dinosauromorphs.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="620" data-original-width="620" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvKPHPsySq3A4ItnlVulYWvKtIfFP5ISAxUAirGR2KZxXbXwBAAYW10UkyAWU5HxVezleM2lxk9A3D6CGttI6wX_hgbQsrEewD-d-vOPZO3TGHWoYcZwb_WRjIYpHDS6PyM6TS_eS7-qA/s320/Dinosauromorphs.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Hayden Quarry dinosauromorphs by Donna Braginetz</td></tr>
</tbody></table>
Shuvosaurids were living alongside lagerpetids, silesaurids,
and basal theropods (like <i style="mso-bidi-font-style: normal;">Tawa, Chindesaurus, </i>and <i style="mso-bidi-font-style: normal;">Coelophysis</i>)<i style="mso-bidi-font-style: normal;"> </i>during what I assume to be their entire history. And that’s weird
because all four of these groups had similar bauplans and were not too
disparate in size (see image at left which does not include a shuvosaurid). However, they likely avoided direct competition by going
after different food: shuvosaurids were probably herbivores and/or insectivores, silesaurids were definitely
herbivores, and basal theropods were predators of small vertebrate game. Can’t
really be sure what <i style="mso-bidi-font-style: normal;">Dromomeron</i> was
eating because there’s no skull material associated with any specimens (that I
know of), but as a lagerpetid, I have to assume it was predating insects and
tiny vertebrates.<br />
<br /></div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFaEWmR2ZEAnToMkYmV7eMbTKkrzuSWao_rsqvrEoHJ60rhrQw-SGFoPLNS0V3ivRc8eGEoAwSIwr-6dM_cpm-UKdiI_9WnsDDwCCoiWBowRs3xsCXC35uQ__6O1TP1SioqUJ3rZwyYIY/s1600/Effigia+Ankle.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="415" data-original-width="371" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFaEWmR2ZEAnToMkYmV7eMbTKkrzuSWao_rsqvrEoHJ60rhrQw-SGFoPLNS0V3ivRc8eGEoAwSIwr-6dM_cpm-UKdiI_9WnsDDwCCoiWBowRs3xsCXC35uQ__6O1TP1SioqUJ3rZwyYIY/s200/Effigia+Ankle.jpg" width="178" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Effigia</i>'s "crocodile-normal" ankle</td></tr>
</tbody></table>
I wonder if the shuvosaurid ankle structure, which Nesbitt
(2007) compares to <i style="mso-bidi-font-style: normal;">Alligator</i>,
differentiated it from contemporary ornithodirans. Ornithodirans have limited
motion in the ankle joint, being only able to bend the foot in a fore-and-aft
arc. Crocodilians, however, have some rotation in the foot relative to the
lower leg. Unfortunately, I don’t think
anybody’s done any speculation on the functional morphology of these suchian
dinosaur-mimics. Paleoartist Gabriel Ugueto has wondered if shuvosaurids were <a href="https://twitter.com/SerpenIllus/status/987044406141358082">plantigrade or not</a> given their ankle structure--I tend to think walking would've been difficult if they were flat-footed but it's an interesting question. <i>Effigia</i> remains the youngest shuvosaurid known, living alongside <i>Coelophysis</i> towards the end of the Late Triassic. The group does not appear to have survived the End-Triassic Extinction. Perhaps their niche was taken over by basal ornithischians.<br />
<br />
Anyway, there you have it. Shuvosaurids remain my favorite example of convergent evolution, even moreso than fully-shelled placodonts or dolphin-shaped ichthyosaurs. These are animals that, if you never found their ankle bones, might today be classified as aberrant theropods.</div>
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<o:p></o:p></div>
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*This group (sail-backed poposaurs) fascinates me and I
don’t understand why nobody’s gotten around to describing <i style="mso-bidi-font-style: normal;">Lotosaurus</i>, an especially interesting taxon whose skeleton and skull are apparently completely
known based on dozens of individuals who all died together. It was “announced”
in a one-paragraph paper from 1975 (Zhang) and since then there’s only been a
publication on the taphonomy of a giant <i style="mso-bidi-font-style: normal;">Lotosaurus</i>
bonebed (Hagen et al. 2018) but no real osteological description has been put
forward.<o:p></o:p></div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-47022851799867894082018-05-14T11:48:00.000-07:002018-05-14T11:50:37.363-07:00One More Strange Reptile<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwZuoVsAnuD0ZvEVPa45CRFmw62Zb8-9qTPqJh9i1YHizE7nkT9M0maPkRGLITDqTtDD7YNv02MglSz7E8nTDGk_wwf3WdxbJlHJbUSE3ZSTTMRaib34IMFdOzX0HSXiSJqT3lTYu5uYU/s1600/Teraterpeton.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="675" data-original-width="1200" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwZuoVsAnuD0ZvEVPa45CRFmw62Zb8-9qTPqJh9i1YHizE7nkT9M0maPkRGLITDqTtDD7YNv02MglSz7E8nTDGk_wwf3WdxbJlHJbUSE3ZSTTMRaib34IMFdOzX0HSXiSJqT3lTYu5uYU/s320/Teraterpeton.jpg" width="320" /></a></div>
<br />
Remember my post from last year about azendohsaurs and trilophosaurs? Well just the other day, paleoartist extraordinaire Gabriel Ugueto <a href="https://twitter.com/SerpenIllus/status/993847242078523392">posted a sketch</a> of something called <i>Teraterpeton</i>. I had no idea what this zany-looking reptile was, so I looked it up and was flabbergasted to find that it's a trilophosaur that is quite unlike <i>Trilophosaurus</i>. You'll notice that I did mention <i>Teraterpeton</i> in passing in that post, which must mean I didn't think it was a trilophosaur or at least was not unambiguously a trilophosaur. Turns out I'm incorrect--<i>Teraterpeton </i>is a perfectly good trilophosaur, and therefore an allokotosaur!<br />
<a name='more'></a><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhH0l8jc6hJjQjvJTbk-7V8hcPe8rxDra-pMfm3AJLGY4_msuenMLOckTng5mh89d7ZaA6cE02p3_kS1YPh9LUu2BORdjBXBW7z1cjOJokDm6RILV1d9AUK1ZWMExC85nxjcrrwCIAMmPw/s1600/Teraterpeton+Skull.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="259" data-original-width="781" height="106" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhH0l8jc6hJjQjvJTbk-7V8hcPe8rxDra-pMfm3AJLGY4_msuenMLOckTng5mh89d7ZaA6cE02p3_kS1YPh9LUu2BORdjBXBW7z1cjOJokDm6RILV1d9AUK1ZWMExC85nxjcrrwCIAMmPw/s320/Teraterpeton+Skull.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A drawing of the header image from Sues (2003).</td></tr>
</tbody></table>
Hans-Dieter Sues <a href="http://www.nrcresearchpress.com/doi/abs/10.1139/e02-048?journalCode=cjes#.WvnYcWgvyUk">named and described</a> <i>Teraterpeton hrynewichorum</i> based on a wonderful skull, a partial skeleton, and a referred right dentary. Now, even for a Late Triassic hellasaur, <i>Teraterpeton</i> is pretty trippy: the skull is long and low, characterized by a short maxilla, where the teeth are concentrated, followed by an extremely long, toothless snout that may have ended in a beak. The maxillary teeth occlude with matching teeth at the back of the dentary. Like <i>Trilophosaurus, </i>the lateral temporal fenestrae is closed off. You may think that <i>Teraterpeton</i> has an extremely large antorbital fenestrae and that the naris is quite small.<br />
<br />
In fact, that's probably not the case. <i>Trilophosaurus</i> lacks an antorbital fenestrae, as do the closely-related azendohsaurs. Sues initially believed the large opening to be an antorbital fenestra but, given what bones it's bordered by, "the opening most likely represents a greatly enlarged external narial fenestrae." Indeed, the premaxillae are extremely long and the nasals have been reduced to oddly-shaped bones that have been shoved backwards toward the skull roof. Behind them, the prefrontals form small lateral flanges overhanging the orbits.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY4R5xNPZ-3oFT7FP2Qb2E68La3C2U42pjN-Xbmap3LBEwormmWyJ92ccv8lFPKT8bBo71HAz99HgA0_PkwiAcrRaPc5VzThJBGOSmgpXZAKHVACQ5MIJAt6k8kg00NsyvJgYx4RN8JiQ/s1600/Teraterpeton+Jaw.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="398" data-original-width="512" height="248" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY4R5xNPZ-3oFT7FP2Qb2E68La3C2U42pjN-Xbmap3LBEwormmWyJ92ccv8lFPKT8bBo71HAz99HgA0_PkwiAcrRaPc5VzThJBGOSmgpXZAKHVACQ5MIJAt6k8kg00NsyvJgYx4RN8JiQ/s320/Teraterpeton+Jaw.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dentary dentition</td></tr>
</tbody></table>
The mandibles match the structure of the skull. Each tooth has a single tall cusp and a smaller "heel." The teeth are wider than they are long, which is expected for a trilophosaur, but they are otherwise quite different from <i>Trilophosaurus</i>. Interestingly (to me, anyway), each tooth has a "collar" of thin bone below its bulbous base that covers up what would be the upper portion of the root. <i>Teraterpeton</i> also surprisingly large palatal teeth that run right up against the maxillary teeth and are of the same morphology.<br />
<br />
The rest of the skeleton is mostly unremarkable although the incomplete right manus has distinctive claws: they are tall but narrow and "blade-like." This is also a major difference from <i>Trilophosaurus</i>, who has slender fingers and relatively small claws. <i>Trilophosaurus</i> is usually considered arboreal, but what was <i>Teraterpeton</i> doing?<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHL-f14DoJUQSI-hKuJy8BAcgNWkWR2ETLXID0NWhWELbedjxaEgA-GtTQD-fBtcdVCQZUQKG6Rdecw5cy1jfJliOFoVU84siTHZ3iX9wirGfiGjqxWM3wPtUjDGPEaH__QkWQ8m2abCk/s1600/Teraterpeton+Claws.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="288" data-original-width="623" height="147" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHL-f14DoJUQSI-hKuJy8BAcgNWkWR2ETLXID0NWhWELbedjxaEgA-GtTQD-fBtcdVCQZUQKG6Rdecw5cy1jfJliOFoVU84siTHZ3iX9wirGfiGjqxWM3wPtUjDGPEaH__QkWQ8m2abCk/s320/Teraterpeton+Claws.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The intimidating claws of <i>Teraterpeton</i></td></tr>
</tbody></table>
Well, at SVP 2016, Pritchard & Sues reported on new <i>Teraterpeton</i> material, including a complete pelvic girdle and hind limbs, and the base of the tail. The pelvic girdle shares features with a bunch of unrelated groups like rhynchosaurs, tanystropheids, and lepidosaurs (but were likely homoplastic and not indicative of a close relationship) and the calcaneum is similar to <i>Azendohsaurus</i>. The pedal claws are just like the manual claws. Despite the marked differences between <i>Trilophosaurus</i> and <i>Azendohsaurus</i>, Pritchard & Sues still found <i>Teraterpeton</i> to be a trilophosaurid, and trilophosaurids are the sister group of <i>Azendohsaurus</i> (which we already knew thanks to Nesbitt et al. (2015)). However, Pritchard & Sues did not--at least according to their abstract--comment on how <i>Teraterpeton</i> differed in terms of lifestyle from <i>Trilophosaurus</i>.<br />
<br />
It was almost certainly not arboreal, but the large claws; long, toothless snout; and closely-packed occluding teeth remind me of burrowing insectivores like aardvarks and armadillos who slurp up bugs and grubs with a long tongue and crunch them up with strong molars. Note that this is not the same as specializing for eating eusocial insects like termites or ants: in those animals, dentition is typically reduced in size or lost entirely. For example, anteaters are completely toothless and aardwolves have extremely small molars.<br />
<br />
I'm coming around to the idea that <i>Teraterpeton</i> was the Late Triassic equivalent of the aardvark. But this also speaks to the great morphological distance between <i>Teraterpeton</i>, a burrowing aardvark-like animal, and <i>Trilophosaurus</i>, an arboreal iguana-like animal. It makes me think that the Trilophosauridae is far more diverse than we currently know, which is an exciting thought!<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcEtKqHSAb98oeoZFO8Y4KqUp2_48yVE1SljE_SLgZ8PCURwAOr9MsZrNQ68E5v5KB3064SlYKRpNEQZvyZfOAANWYQpKedlN_R18mWtBTSID7M3tpqpNWH4vpZ24zt90dgun0LFnIMtQ/s1600/Aardvark.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="681" data-original-width="960" height="227" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcEtKqHSAb98oeoZFO8Y4KqUp2_48yVE1SljE_SLgZ8PCURwAOr9MsZrNQ68E5v5KB3064SlYKRpNEQZvyZfOAANWYQpKedlN_R18mWtBTSID7M3tpqpNWH4vpZ24zt90dgun0LFnIMtQ/s320/Aardvark.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An adorable aardvark emerging from its burrow, from Wikipedia.</td></tr>
</tbody></table>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-89592493411269070412018-04-28T17:54:00.000-07:002018-05-01T18:46:21.156-07:00Adorable Triassic Pseudosuchians<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi829762UAWjv1Vw6YQbjRekw73gH1qviXl7nBbM1wGJvD4Wz9fmnMoqjs9GZBB_Fi9WTFuPB4BDxcqsJwuEFAo51LBr7TQFYti7Nt0Kcttv5MeEF5TX8HN3YtMWbWOpGHdN7kuDwWHu8Q/s1600/Erpetosuchus+NA.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="223" data-original-width="751" height="95" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi829762UAWjv1Vw6YQbjRekw73gH1qviXl7nBbM1wGJvD4Wz9fmnMoqjs9GZBB_Fi9WTFuPB4BDxcqsJwuEFAo51LBr7TQFYti7Nt0Kcttv5MeEF5TX8HN3YtMWbWOpGHdN7kuDwWHu8Q/s320/Erpetosuchus+NA.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Erpetosuchus sp.</i> from North America</td></tr>
</tbody></table>
Erpetosuchids are one of those groups that I saw reference
to somewhere, filed it away in the recesses of my brain, and didn’t remember
again until I read the new paper by Nesbitt et al. (2018) about the brain and
endocast of <i style="mso-bidi-font-style: normal;">Parringtonia</i> <i style="mso-bidi-font-style: normal;">gracilis</i>. There’s a gorgeous skeletal
restoration on page 124 and that skull looked awfully familiar to me. Oh yes,
it looks a whole lot like the skull of <i style="mso-bidi-font-style: normal;">Erpetosuchus
grandi</i>, a taxon I first read about thanks to Benton & Walker (2002)
probably a decade ago. With a little more digging, I found that the
Erpetosuchidae is a small but charismatic family of mid-sized pseudosuchians
with unusual dentition and surprisingly croc-like armor. This is one of those
small, obscure groups of Triassic hellasaurs that I like to put in the
spotlight, if even briefly.<br />
<br />
<a name='more'></a><br />
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Little <i style="mso-bidi-font-style: normal;">Erpetosuchus
grandi</i> was named and described in 1893 by E. T. Newton and redescribed in
2002 by Benton & Walker. Newton recognized that <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> was related to crocodilians but considered it closer
to phytosaurs or aetosaurs. While the original specimen was found in
northeastern Scotland, a partial skull has turned up in Connecticut (Oslen et
al. 2000), which may represent a different species. Newton’s fossil represented
essentially the front third of the animal, including a complete skull. The
skull and mandible, however, was a natural mold in the rock and Newton used
gutta percha material (which is what golf balls are made of) to produce casts
from these molds. The results are extraordinarily detailed, even capturing fine
details of the outer surface of the skull bones.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEii2-zeBueAY5U7xoJgbrMhzHhjut2ucaPzRSVqPFy7Qxut1dJ9kFydpQOQhwZCPbTCIsj2aR84kyxpFT3wtEaJ4SwlvEHII-mEVaqEh2Jx1eQzTVYxAwzTooDu9N9cZmqVJJXIuQ3gWao/s1600/Erpetosuchus+Skull.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1346" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEii2-zeBueAY5U7xoJgbrMhzHhjut2ucaPzRSVqPFy7Qxut1dJ9kFydpQOQhwZCPbTCIsj2aR84kyxpFT3wtEaJ4SwlvEHII-mEVaqEh2Jx1eQzTVYxAwzTooDu9N9cZmqVJJXIuQ3gWao/s320/Erpetosuchus+Skull.jpg" width="269" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skull of <i>Erpetosuchus</i> from Benton & Walker</td></tr>
</tbody></table>
The skull of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>
is interesting in a number of ways. For me, the most surprising detail is how
few teeth it has. There are four small, recurved teeth in the premaxilla and
just four larger recurved teeth in the anterior-most section of the maxilla.
The rest of the maxilla is toothless, although Benton & Walker suspect that
at least two teeth were broken off behind the first four. The situation is
similar on the dentary—several recurved teeth of varying size are found in the
anterior section of the dentary, but then there is a shot gap before three
larger recurved teeth appear. It’s not clear whether that gap represents an
actual toothless gap or if there are missing teeth. However, it should be noted that the
dentary has more teeth than the premaxilla and maxilla.<o:p></o:p></div>
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<i style="mso-bidi-font-style: normal;"><br /></i>
<i style="mso-bidi-font-style: normal;"><br /></i>
<i style="mso-bidi-font-style: normal;"><br /></i>
<i style="mso-bidi-font-style: normal;"><br /></i>
<i style="mso-bidi-font-style: normal;">Erpetosuchus</i> has a
particularly large fossa surrounding the antorbital fenestrae. Both the maxilla
and the jugal have distinct, large ventral portions that are flattened or at
the very least diagonally-facing towards the outside edge of the skull. As a
result of this, the palatine bones are narrow—packed in between the flattened
ventral surfaces of the maxilla and anterior jugal. The ectopterygoids are
quite deep, again due in part to the weirdly diagonally-directed ventral
surface of the jugal. In lateral view, the orbits look a bit like an oval
that’s in the process of tipping over, but in dorsal view they are more or
essentially circles. If you squint, the back of the skull (in lateral view)
looks a bit like that of my alligator skull in that the quadrate is strongly
diagonally-directed, the squamosal overhangs it, and there’s a small gap
between the quadrate and the quadratojugal. Unlike my alligator, however, the
lower temporal fenestra of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>
is enormous and deeply recessed.<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigcAkTtQjzy-AU86I6iqc9v0L5jx6BlBGGWy1qaYrncW6sgXy9Z0Kr6at82OBTkf2dFb5sj6dEv5lgwsSx14cT-QLPVXpr93GR4eb7rC_4dZ6C_G_6gK-IGVQT15FJ02q6IEGstaiyupA/s1600/Erpetosuchus+Restoration.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1079" data-original-width="1600" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigcAkTtQjzy-AU86I6iqc9v0L5jx6BlBGGWy1qaYrncW6sgXy9Z0Kr6at82OBTkf2dFb5sj6dEv5lgwsSx14cT-QLPVXpr93GR4eb7rC_4dZ6C_G_6gK-IGVQT15FJ02q6IEGstaiyupA/s320/Erpetosuchus+Restoration.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Skeletal restoration from Benton & Walker</td></tr>
</tbody></table>
<br />
<i style="mso-bidi-font-style: normal;">Erpetosuchus</i>
probably has seven cervical vertebrate—the transition between neck and torso is
not clear. In any case, it had a very short neck. Its neck and back, however,
were covered by two parallel rows of rectangular scutes. Two additional rows
may have begun behind the pectoral girdle. Given the proportions of the
pectoral elements, Benton & Walker suspect that <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> was a bipedal cursor, and its dentition suggests an
insectivorous diet. Their phylogenetic analysis (keep in mind this is 2002), <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> was found to be a sister
group of Crocodylomorpha among then-known croc-line archosaurs. The authors
suggest that fragmentary African taxon <i style="mso-bidi-font-style: normal;">Parringtonia</i>
may represent another erpetosuchid, but more material will be needed to make
that determination. They also note that Germany’s <i style="mso-bidi-font-style: normal;">Dyoplax</i> was initially referred to the Erpetosuchidae but it has
since been reassigned as a genuine basal crocodylomorph. Well, we’ll quickly be
revisiting both of these genera.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKQdLofE6_S42lk4Wj9_WbJgFhZbEXUZKgltByKgwH0O1-aRyoAKVhof76ju2nV0GWEMv_AOzW5cYjncn0TpwGwmKt6x-Ggkh0vcdb_kmglFVmLRiKa5CXJjGwQeLnNVDt6Tsck6Yhlt0/s1600/Dyoplax.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="177" data-original-width="975" height="72" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKQdLofE6_S42lk4Wj9_WbJgFhZbEXUZKgltByKgwH0O1-aRyoAKVhof76ju2nV0GWEMv_AOzW5cYjncn0TpwGwmKt6x-Ggkh0vcdb_kmglFVmLRiKa5CXJjGwQeLnNVDt6Tsck6Yhlt0/s400/Dyoplax.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Looks like a mummy, right? More like a natural mold.</td></tr>
</tbody></table>
<i style="mso-bidi-font-style: normal;">Dyoplax arenaceus</i>
was initially described by Fraas in 1867. Unlike <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>, <i style="mso-bidi-font-style: normal;">Dyoplax</i> is
known from a single essentially complete skeleton. Fraas did not attempt to
classify it, and over the years it wound up in various families—the Aetosauria
in 1902, the Erpetosuchidae in 1961, and the Crocodylomorpha in 1998 after
Lucas et al. redescribed it for the first time. In 2013, Maisch et al.
re-evaluated the skeleton in light of Benton & Walker’s revision of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>. While virtually complete
apart from most of the limbs and tip of the tail, the holotype of <i style="mso-bidi-font-style: normal;">Dyoplax</i> is, like Newton’s <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> specimen, preserved as a
natural cast. Unfortunately, this cast is not as finely-detailed as Newton’s,
so many details of <i style="mso-bidi-font-style: normal;">Dyoplax</i> are lost
or at least ambiguous.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8f8V2tGmgh2gjmB9x4XJOZ5HHA82mNvM49uH1Vaww6S9-1oDHpqmKty-g5d_NC9kK38s_1EBh7RGepepOj7723no11-5VuM7WcbY-oqlQ-DwMZ9pf01mhl_5c2AbjxXd9_aWcAcn-xW8/s1600/Dyoplax+Skull.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1095" data-original-width="975" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8f8V2tGmgh2gjmB9x4XJOZ5HHA82mNvM49uH1Vaww6S9-1oDHpqmKty-g5d_NC9kK38s_1EBh7RGepepOj7723no11-5VuM7WcbY-oqlQ-DwMZ9pf01mhl_5c2AbjxXd9_aWcAcn-xW8/s320/Dyoplax+Skull.jpg" width="284" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A "best guess" <i>Dyoplax</i> skull from Maisch et al.</td></tr>
</tbody></table>
The skull is restored as roughly resembling that of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>, but shallower, with a less-exaggerated
antorbital fossa. The authors don’t comment on the postcrania aside from noting
that <i style="mso-bidi-font-style: normal;">Dyoplax</i> also has median
osteoderms running down the back, and seem unique to <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> among crurotarsians. Honestly, the specimen looks like
a cheaply-made plaster cast so I’m not surprised nobody has been able to do a
detailed description. Maisch et al. note
that only Walker suspected that <i style="mso-bidi-font-style: normal;">Dyoplax</i>
may be an erpetosuchid. Even Benton & Walker accepted Lucas’ reference to
the Sphenosuchia. However, Maisch et al. point out several features that
readily link <i style="mso-bidi-font-style: normal;">Dyoplax</i> and <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>, but given the poor
preservation of the specimen, the authors refrain from definitely assigning <i style="mso-bidi-font-style: normal;">Dyoplax</i> to the Erpetosuchidae but they
strongly suspect that it belongs there.<o:p></o:p></div>
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More interestingly, Maisch et al. consider the possibility
that<i style="mso-bidi-font-style: normal;"> Dyoplax</i> is actually a German
specimen of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>. If they are
the same, then <i style="mso-bidi-font-style: normal;">Dyoplax</i> has priority,
as it was described almost thirty years before <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>. <o:p></o:p></div>
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“Both taxa are from at least
roughly coeval beds, and they are also strikingly similar in size. This is
particularly important because it excludes the possibility that observed
differences may be attributable to ontogeny.” <o:p></o:p><br />
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However, after considering that differences in armor
preservation may be taphonomic rather than taxonomic, the authors note that
many of the differences in the two animals’ skulls—especially regarding the
size and shape of the antorbital fenestra—appear to be genuine. Although it
remains an intriguing possibility, Maisch et al. conclude that without better
specimens of <i style="mso-bidi-font-style: normal;">Dyoplax</i>, synonymizing
the two is premature.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeAjXvnKxApS35a280NjTNEITuLflZhb1VO35Z2jevZDKhdpXE5dlsKbyGiazLBlj0ANmmUeIjnYGakBNvv_k7WElMgkZB3lwYYTg7eJx53lzPKm_J06VSfgb6zR3K_P4AQjMogaZ1wzc/s1600/Tarjadia+Skull+Fragment.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="787" data-original-width="861" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeAjXvnKxApS35a280NjTNEITuLflZhb1VO35Z2jevZDKhdpXE5dlsKbyGiazLBlj0ANmmUeIjnYGakBNvv_k7WElMgkZB3lwYYTg7eJx53lzPKm_J06VSfgb6zR3K_P4AQjMogaZ1wzc/s200/Tarjadia+Skull+Fragment.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fragment of the skull table of <i>Tarjadia</i></td></tr>
</tbody></table>
In 1998, Acrucci & Marsicano described a “distinctive
new archosaur,” <i style="mso-bidi-font-style: normal;">Tarjadia ruthae</i>, from
Argentina. Sadly, the holotype consists of six “almost complete” dorsal
osteoderms, fragments of a few more, and all found in association with
fragmentary vertebrae. They refer a bunch of skull fragments to the same taxon.
Unfortunately, but maybe not surprisingly, the authors could not classify <i style="mso-bidi-font-style: normal;">Tarjadia</i> as anything other than a “basal
crurotarsal archosaur.” This is another taxon we’ll be revisiting soon.<o:p></o:p></div>
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First, let’s take a hard left to the Doswelliidae, a group
of basal archosauriforms that also had distinctive armor. Desojo et al. (2011)
described <i style="mso-bidi-font-style: normal;">Archeopelta arborensis</i>, a
Brazilian taxon known from a braincase, a long string of dorsal vertebrae, a
sacrum with attached pelvis (and right femur), a right humerus and several
osteoderms. Those authors found that <i style="mso-bidi-font-style: normal;">Archeopelta</i>,
<i style="mso-bidi-font-style: normal;">Doswellia</i>, and Arcurri &
Marsicano’s <i style="mso-bidi-font-style: normal;">Tarjadia</i> share two
features related to the structure of the osteoderms. Admitting that the
holotype of <i style="mso-bidi-font-style: normal;">Tarjadia</i> hardly provides
a robust set of characters, Desojo et al. removed it from their analysis and
found eight non-osteoderm characters that united <i style="mso-bidi-font-style: normal;">Doswellia</i> and <i style="mso-bidi-font-style: normal;">Archeopelta</i>.<o:p></o:p><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlVC62gxfUilrp512Ot9bqhRhiEVTMzeOZEOyoppUOl_G8LpqIPOzesleZjqPkbqdiNJ4IY7ctLLasv_cf5OI_DdzUKFPdWKmNW4JlhP7VpkmaeYQx3fqOi5lBEQi8w3GngYTP1Vvovds/s1600/Archeopelta+the+Doswellid.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="214" data-original-width="1341" height="51" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlVC62gxfUilrp512Ot9bqhRhiEVTMzeOZEOyoppUOl_G8LpqIPOzesleZjqPkbqdiNJ4IY7ctLLasv_cf5OI_DdzUKFPdWKmNW4JlhP7VpkmaeYQx3fqOi5lBEQi8w3GngYTP1Vvovds/s320/Archeopelta+the+Doswellid.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Desojo et al. used a <i>Doswellia</i> skeletal in their <i>Archeopelta</i> description.</td></tr>
</tbody></table>
However, just two years later, in their description of Texan
doswellid <i style="mso-bidi-font-style: normal;">Ankylosuchus chinlegroupensis</i>,
Lucas et al. (2013) assert that most of the diagnostic characters of <i style="mso-bidi-font-style: normal;">Archeopelta</i> cannot be distinguished from
those of <i style="mso-bidi-font-style: normal;">Tarjadia</i>, simply because <i style="mso-bidi-font-style: normal;">Tarjadia</i> is so poorly-represented. They
thus determine that <i style="mso-bidi-font-style: normal;">Archeopelta</i> is a
junior synonym of <i style="mso-bidi-font-style: normal;">Tarjadia</i>—at least
until better remains of the latter are found....HINT HINT.</div>
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<o:p></o:p></div>
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In his massive 2016 phylogeny of basal archosaurs, Ezcurra
found that the two really do differ in important ways, resurrecting <i style="mso-bidi-font-style: normal;">Archeopelta</i>, and placing them all, once
again, in a monophyletic Doswelliidae.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRBJ8C9eJ0v3pVCHtbdkdEg5QSMujLSKsnqD8dx4-uk0IZ1ejToTIptllj4XCjiMvrBpLwz_dbty07ANgKrPLT0LdRtsGtbfbKOEc70uOHKpH72g0MjfhV2FqxFDWDUp44VACVQLxzybg/s1600/Parringtonia+Maxilla.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="627" data-original-width="1600" height="125" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRBJ8C9eJ0v3pVCHtbdkdEg5QSMujLSKsnqD8dx4-uk0IZ1ejToTIptllj4XCjiMvrBpLwz_dbty07ANgKrPLT0LdRtsGtbfbKOEc70uOHKpH72g0MjfhV2FqxFDWDUp44VACVQLxzybg/s320/Parringtonia+Maxilla.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The maxilla of <i>Parringtonia</i></td></tr>
</tbody></table>
Now before we get to the thrilling conclusion, let’s introduce
<i style="mso-bidi-font-style: normal;">Parringtonia gracilis</i>, pretty much
the only other erpetosuchid that was recognized as such relatively quickly.
Huene (1939) described this fragmentary beasty from Tanzania. Represented by a
worn-down maxilla, scapula, ischium, some dorsal and caudal vertebrae, and
osteoderms, <i style="mso-bidi-font-style: normal;">Parringtonia</i> did not
present a terribly exciting fossil and Huene could not decide whether it was an
ornithosuchid, basal crocodylomorph, or new lineage. A couple decades later,
Krebs (1965) noted the similarities between the scapulae of <i style="mso-bidi-font-style: normal;">Parringtonia</i> and <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>. Walker (1970) ran with that idea, including
both—almost with <i style="mso-bidi-font-style: normal;">Dyoplax</i>—in a new
family, the Erpetosuchidae, but six years later, Krebs removed <i style="mso-bidi-font-style: normal;">Dyoplax</i> and, as you’ll recall, Benton
& Walker (2002) were not convinced that <i style="mso-bidi-font-style: normal;">Parringtonia</i>
really was an erpetosuchid. So, once again, Erpetosuchidae is left with just <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiN5eX716Bk4MlEtfXVysLoxI3ivI9xf1R1vNe2J5siHNaF1icgYYJVQLz5NedLIlVMFLe53CG0RuCObv2RZP6G7Ow7DLmXlp-lF7DjcDAG5KqaNxD-cO-sZqczznVA69MioIAT4TP5aYU/s1600/Tarjadia+Revealed.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1380" data-original-width="1600" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiN5eX716Bk4MlEtfXVysLoxI3ivI9xf1R1vNe2J5siHNaF1icgYYJVQLz5NedLIlVMFLe53CG0RuCObv2RZP6G7Ow7DLmXlp-lF7DjcDAG5KqaNxD-cO-sZqczznVA69MioIAT4TP5aYU/s320/Tarjadia+Revealed.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Tarjadia</i> revealed! Yellow bones remain unknown.</td></tr>
</tbody></table>
Now then, let’s take a quick detour back to <i style="mso-bidi-font-style: normal;">Tarjadia. </i>As reported in Ezcurra et al.
(2017), new specimens of <i style="mso-bidi-font-style: normal;">Tarjadia</i> now
represent almost every bone of the body excluding only the feet, hands, and
most of the tail. And it looks an awful lot like <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>. In their analysis, <i style="mso-bidi-font-style: normal;">Tarjadia</i> joins <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>,
<i style="mso-bidi-font-style: normal;">Dyoplax</i>, <i style="mso-bidi-font-style: normal;">Archeopelta</i>, and <i style="mso-bidi-font-style: normal;">Parringtonia</i>
in a monophyletic Erpetosuchidae, which is the sister group of Ornithosuchidae.*
Erpetosuchidae + Ornithosuchidae is the sister group to the heavily-armored,
snub-nosed Aetosauria. I should note, however, that Nesbitt & Butler (2013)
could not determine exactly where Erpetosuchidae fell on the Archosauria tree,
and could be either a very early-diverging member or fairly derived relative of
aetosaurs and <i style="mso-bidi-font-style: normal;">Revueltosaurus</i>. Based
on braincase characters, Nesbitt et al. (2018) found Erpetosuchidae as an outgroup
to (Aetosauria + <i style="mso-bidi-font-style: normal;">Revueltosaurus</i>)—essentially
the earliest-diverging suchians.<o:p></o:p></div>
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It turns out that Huene’s <i style="mso-bidi-font-style: normal;">Parringtonia</i> is in the same camp as <i style="mso-bidi-font-style: normal;">Tarjadia</i>: Nesbitt et al. (2018) report that new specimens of <i style="mso-bidi-font-style: normal;">Parringtonia</i> have revealed virtually its
entire skeleton and guess what? It’s very clearly an erpetosuchid. <o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikQk-pmaa_OEI_5i6gqTYg2QPywES4LoAmaE2JPWvu9J0fQbr9J5pbv0EOHHddkLisqN6H2vLMY8IiLa-SqF0dTygdHJ89NF2C3TltNH3XyoGYT96rUbcelozdQAiK3LOO_1wX2Zj3T4s/s1600/Parringtonia+Revealed.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="524" data-original-width="1600" height="130" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikQk-pmaa_OEI_5i6gqTYg2QPywES4LoAmaE2JPWvu9J0fQbr9J5pbv0EOHHddkLisqN6H2vLMY8IiLa-SqF0dTygdHJ89NF2C3TltNH3XyoGYT96rUbcelozdQAiK3LOO_1wX2Zj3T4s/s400/Parringtonia+Revealed.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Parringtonia</i> revealed! Look at how big its head is compared to the body.</td></tr>
</tbody></table>
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And finally, literally as I was getting read to press "Publish," another erpetosuchid appeared in the literature: <i>Pagosvenator delariensis</i> from Brazil, described by Lacerda et al (2018). The holotype is a mostly complete but pretty beat up skull with mandibles and two incomplete vertebrae and five osteoderms. Like its relatives, <i>Pagosvenator</i> isn't particularly large but the skull looks a whole lot like every other erpetosuchid where good skull material is known.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTsFRqu6O1DJq64rLKScX4ZbFV4o0CJ5WKv8oUTinItYcJPnHqFFDJ3Fbd_kFyaWg3QObdt0rRRlsu1dub9HBG-8-MKbTGVpkO2P277KuCPilp8taO253zAEHHgnGb-_xMJPG3dKf82E8/s1600/Pagosvenator+Skull.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1383" data-original-width="1053" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTsFRqu6O1DJq64rLKScX4ZbFV4o0CJ5WKv8oUTinItYcJPnHqFFDJ3Fbd_kFyaWg3QObdt0rRRlsu1dub9HBG-8-MKbTGVpkO2P277KuCPilp8taO253zAEHHgnGb-_xMJPG3dKf82E8/s320/Pagosvenator+Skull.jpg" width="243" /></a></div>
The authors state that <i>Pagosvenator</i> is the first erpetosuchid from South America, but that doesn't really jive with the existence of <i>Tarjadia</i> (Argentina) or <i>Archeopelta</i> (also Brazil). In fact, if you look through their paper they only mention <i>Tarjadia</i> once, where they compare one of its osteoderms to that of <i>Pagosvenator</i>, and <i>Archeopelta</i> twice--once in the same osteoderm context and a second time where the authors call it a doswellid, citing Desojo et al. (2011). Clearly, this paper must have been in press while Ezcurra et al. (2017) and Nesbitt et al. (2018) were being prepped. The authors run a phylogenetic analysis to try and work out where erpetosuchids (minus <i>Tarjadia</i> and <i>Archeopelta</i>) fit into the rest of Archosauria. In general, their results reflect other recent phylogenies: they're either a sister group to Ornithosuchidae or they're one step above Aetosauria, as a sister group to (Gracilisuchidae + Paracrocodylomorpha).<br />
<br />
Offhand, one wonders if <i>Pagosvenator</i> is potentially a junior synonym of <i>Archeopelta</i>, as both are Brazilian and the latter is so poorly known. Desojo et al. (2011) write that <i>Archeopelta</i> is Landian or Carnian--and so is <i>Pagosvenator</i>. Lacerda et al. (2018) compare the osteoderms of <i>Archeopelta</i> and <i>Pagosvenator</i> but make no other osteological comparisons or even bring <i>Archeopelta</i> up, content to leave it as an unrelated doswellid. However, I think it's possible that the two are synonymous now that Ezcurra et al. (2017) have made a good case for <i>Archeopelta</i> being an erpetosuchid. As I always wind up saying in these essays, more material will be necessary for a more conclusive, uh, conclusion.<br />
<br />
Now, what kinds of animals are these cute little crocs?
While Benton & Walker believed (based on the proportions of the forelimbs)
that <i style="mso-bidi-font-style: normal;">Erpetosuchus</i> could have run
around on its hind limbs if it wanted to, <i style="mso-bidi-font-style: normal;">Parringtonia</i>
and <i style="mso-bidi-font-style: normal;">Tarjadia</i> present much more
traditionally-proportioned quadrupeds. They are also clearly impressively
armored. In addition to the osteoderms running down the back, <i style="mso-bidi-font-style: normal;">Tarjadia</i> at least has osteoderms on its
hind limbs and possibly its forelimbs. In Argentina, <i style="mso-bidi-font-style: normal;">Tarjadia</i> shared its habitat with rhynchosaurs, small mammals, and
mid-to-large-sized carnivorous pseudosuchians. These were dog-sized cursors
going after small game.<br />
<br />
There are several features of the skull that I find
interesting: the enormous fossa surrounding the anteorbital fenestrae; the
enlarged, posteriorly-directed jugal (which gives the lateral temporal fenestra
an odd shape); and the fact that the dentary has significantly more teeth than
the maxilla. It's also strange that the group is so homogeneous--everyone is roughly the same size, with roughly the same skull shape and dentition, and differ mainly in terms of osteoderm compliment (assuming the differences between <i>Tarjadia</i> and <i>Parringtonia</i> are genuine and not the result of missing data).<br />
<br />
This group did not last terribly long: <i>Parringtonia</i> is the earliest member (Ansian) and most of them were extinct by the beginning of the Norian
(although North America’s <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>
appears to be from the late Norian). Prior to the five-minutes-ago publication of Lacerda et al. (2018), a large ghost lineage existed between <i>Parringtonia</i> and everyone else, who turn up in the late Carnian. However, <i>Pagosvenator</i> is from the late Landian/early Carnian, which shortens the temporal gap somewhat. At any rate, erpetosuchids were certainly extinct by the
Rhaetian, and thus were spared from whatever traumatic event caused the
Triassic/Jurassic extinction.<o:p></o:p></div>
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*Funnily enough, in his original description of <i style="mso-bidi-font-style: normal;">Erpetosuchus</i>, Newton also described <i style="mso-bidi-font-style: normal;">Ornithosuchus woodwardi</i>. However, he
thinks that the latter is a very primitive dinosaur or, at least, an immediate
ancestor of dinosaurs.<o:p></o:p></div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com2tag:blogger.com,1999:blog-4675540394850433221.post-59215992719302358492018-04-13T19:29:00.002-07:002018-04-13T19:34:47.146-07:00The Camptosaurus Challenge<div class="separator" style="clear: both; text-align: center;">
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfcmZ6AOZeQ_C1uj-s7OYyF8Bsao1gB4YRXwh_YlSmHnb4qdBXtqyJxCGO0E6t-XlRYBJ0kl089-vz8Q2vVZbshtcglAFINeBAdxCoJVB3jp_HmXxNjE1nr8rjBmvHBf_6R0h15VNeg_I/s1600/Camptosaurus+Skeletal.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="341" data-original-width="966" height="112" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfcmZ6AOZeQ_C1uj-s7OYyF8Bsao1gB4YRXwh_YlSmHnb4qdBXtqyJxCGO0E6t-XlRYBJ0kl089-vz8Q2vVZbshtcglAFINeBAdxCoJVB3jp_HmXxNjE1nr8rjBmvHBf_6R0h15VNeg_I/s320/Camptosaurus+Skeletal.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Camptosaurus dispar</i> skeletal by Scott Hartman</td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
If any of you dear readers follow me on Twitter
(<a href="https://twitter.com/zmiller1902?lang=en">@zmiller1902</a>) or any of my blogger colleagues (there’s a handy list at the
bottom of this post) you’ve probably seen at least a few entries in the hashtag
<i style="mso-bidi-font-style: normal;">Camptosaurus</i> challenge. For the
deets, check out David Orr’s <a href="https://chasmosaurs.com/2018/04/09/the-camptosaurus-challenge/">two</a> <a href="https://chasmosaurs.com/2018/04/10/the-camptosaurus-challenge-strikes-back/">posts</a> on this very topic and the deluge of
paleoart that it inspired. You’ll see that I have two rather terrible
entries—both were rush jobs—but I was determined to put something respectable
together last night and I’m pretty happy with the result:<br />
<br />
<a name='more'></a><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivoTt2E_r7-KeDZnV1n_L65dHv4wTvXGEln8FaFTl3yCfI7kWuUukxNmbsG8TUiqpFKTSn2AJpxCqSIW31BIKumNbX0RfLtulhU0TbgVolpRGQF_FOmzEg-sdFyXoanqzTuUFOsaYRih0/s1600/Campto.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="741" data-original-width="761" height="311" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivoTt2E_r7-KeDZnV1n_L65dHv4wTvXGEln8FaFTl3yCfI7kWuUukxNmbsG8TUiqpFKTSn2AJpxCqSIW31BIKumNbX0RfLtulhU0TbgVolpRGQF_FOmzEg-sdFyXoanqzTuUFOsaYRih0/s320/Campto.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Camptosaurus dispar</i> in anterior view.</td></tr>
</tbody></table>
It’s not perfect, but significantly, it’s not terrible.<br />
<div class="MsoNormal">
<o:p></o:p></div>
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<br /></div>
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I used to draw all the time. And by all the time, I mean <i style="mso-bidi-font-style: normal;">all the time</i>. I would draw on whatever
paper was within arm’s reach, using whatever writing implement was on-hand. I
doodled on homework and, later in life, contract documents. I drew pictures for
my wife, friends, and family. I drew dinosaurs and other prehistoric beasties
for the most part, but I also tinkered with my own creative projects from time
to time and I had designs to learn how to draw pin-up art. My “draw all the
time” phase lasted from the time I could hold a crayon to April, 2011.<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
What happened in April, 2011? I developed a brain abscess. <o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE1S7AsnsobJGoBgpOEFezYTmwj_L6OdZlmruo_zP3xLVdHz32hgEMM12_byAs6_vzpLUg3OY56nJVIuyL-YoJKn1BPlZsQEuW8Nh1KqiFCcrElajh_fd0Te-5xJBuGwJcmR-EaPto_FQ/s1600/IMG_20180412_203710.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE1S7AsnsobJGoBgpOEFezYTmwj_L6OdZlmruo_zP3xLVdHz32hgEMM12_byAs6_vzpLUg3OY56nJVIuyL-YoJKn1BPlZsQEuW8Nh1KqiFCcrElajh_fd0Te-5xJBuGwJcmR-EaPto_FQ/s320/IMG_20180412_203710.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Here's a WIP. I'm usually disappointed by how the inks turn out, but not this time.</td></tr>
</tbody></table>
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For those who don’t know, a brain abscess is when bacteria
(in my case, <i>Streptococcus</i>) gets into
your spinal fluid and travels to your brain, where it sits on the dura mater,
eating away at it until it gets to your brain at which point you’re screwed.
They got to my abscess just in time, before it broke through, and I wound up in
the Adult ICU with a tube coming out of my skull (to drain my spinal fluid) and
a PICC line in my arm pumping me full of penicillin. I survived and had no
physical impairments when I left apart from a tremor in my hands that comes and
goes, but there’s a family history of tremor so it’s probably unrelated.</div>
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<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEx12XHqTTGmr7jyPtgHZGjFnthzYR_ujmBX_58QN5sZ01p5xqUVnn74veHQPGlp_UIXxLDBIBNXnP9chKtC6UFMDiIlzpJMzoLPi707e80xB6LlbetwJjjutm_UGHZDDlu3A6Z8mmbMo/s1600/IMG_20180405_113350.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEx12XHqTTGmr7jyPtgHZGjFnthzYR_ujmBX_58QN5sZ01p5xqUVnn74veHQPGlp_UIXxLDBIBNXnP9chKtC6UFMDiIlzpJMzoLPi707e80xB6LlbetwJjjutm_UGHZDDlu3A6Z8mmbMo/s320/IMG_20180405_113350.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Camptosaurus dispar</i>, V.1</td></tr>
</tbody></table>
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I came out the other side fine except for one critical
thing: drawing. It’s not that I suddenly couldn’t hold a pen or draw a picture,
it was that I had no motivation for doing so. If you sat me down, gave me a
pencil, and told me to draw a <i>Triceratops</i>,
I would do it for you but I wouldn’t do it on my own. This change flabbergasted
my parents and my wife and frankly they still talk about it. I’m still affected
by it, but in the last couple years, I’ve been trying to get back on the horse,
forcing myself to draw from time to time. It never sticks, but I’m hopeful that
this <a href="https://twitter.com/hashtag/camptosauruschallenge">#CamptosaurusChallenge</a> will fix that.</div>
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<o:p></o:p></div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUKxi6ZevxAIbkxfAacBps7STAbi0-t76z77eJatbPr3kgoM4DYq63uXy9P8eWnQFs-fAx0Rmj0Z8-ZdsmK5-byOTuONYQITenquVgX75XaWkdOIU9P3tNA4I9n8dBLyJ58cwMFwdLq_I/s1600/IMG_20180405_181044.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUKxi6ZevxAIbkxfAacBps7STAbi0-t76z77eJatbPr3kgoM4DYq63uXy9P8eWnQFs-fAx0Rmj0Z8-ZdsmK5-byOTuONYQITenquVgX75XaWkdOIU9P3tNA4I9n8dBLyJ58cwMFwdLq_I/s320/IMG_20180405_181044.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Camptosaurus dispar, V.2</i></td></tr>
</tbody></table>
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That picture up there took a long time to finish—probably an
hour—but I’m very happy with the result, especially considering it’s an angle
(anterior view) that I’m unfamiliar with. Maybe the most surprising thing,
though, is that after almost exactly seven years of not drawing, I can produce
something this good (and I’m not saying this is a good drawing, I’m saying it’s
good <i>for me</i>). It proves that all that
muscle memory is still intact and easily accessible. I have hope that this
challenge will be the spark that reignites my love of drawing.</div>
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<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
Oh, I guess I drew this for my wife for her birthday last
month:<o:p></o:p></div>
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<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuwERdf0IcqNP6m9L9Zt9fO011V3N5OaRPSLe4f_PbGcwdWJ2Wj9-NbgI7T_cyXs0YlH-Sid48C_KKk1zcOe5xo7wdzZgEKret3l0Zv32SqLzuWHQoi5hbrN7nVNmG07CaXn1Z0AuEzNY/s1600/IMG_20180214_100224.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuwERdf0IcqNP6m9L9Zt9fO011V3N5OaRPSLe4f_PbGcwdWJ2Wj9-NbgI7T_cyXs0YlH-Sid48C_KKk1zcOe5xo7wdzZgEKret3l0Zv32SqLzuWHQoi5hbrN7nVNmG07CaXn1Z0AuEzNY/s320/IMG_20180214_100224.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Halszkaraptor escuilliei </i>in right lateral view.</td></tr>
</tbody></table>
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It’s supposed to be <i>Halszkaraptor</i>,
but I may have gone overboard with the fluff (blame <a href="http://dinogoss.blogspot.com/2013/06/youre-doing-it-wrong-cgi-feathered.html">Matt Martyniuk</a>). This isn’t
bad either but I’m not quite as happy with it as I am with the <i>Camptosaurus</i>.</div>
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<o:p></o:p></div>
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Anyway, here’s hoping my next post features illustrations
that I do my goddamn self.<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
And here's that list of folks you should follow on Twitter. I've also updated my Links of Interest on the sidebar--long overdue. If I forgot somebody, let me know and I’ll include you too. I’m going
largely from memory and my memory is terrible. I'm far too lazy to post links to everyone's Twitter accounts, so you'll have to input these the old-fashioned way. You know, I might just make a new sidebar...thing...for Twitter. But later.<o:p></o:p></div>
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<br /></div>
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Andrea Cau: @TheropodaBlog<br />
Andrey Atuchin: @AndreyAtuchin<br />
Brian Eng: @GreyGriffon<br />
Brian Switek: @Laelaps<br />
Darren Naish: @TetZoo<br />
David Hone: @Dave_Hone<br />
David Orr: @anatotitan<br />
Ed Yong: @edyong209<br />
Emily Willoughby: @eawilloughby<br />
Ethan Kocak: @blackmudpuppy<br />
Gabriel Ugueto: @Serpenillus<br />
Glendon Mellow: @FlyingTrilobite<br />
Jaime Headden: @JaimeHeadden<br />
Julius Csotonyi: @JCsotonyi<br />
Mark Witton: @MarkWitton<br />
Matt Celeskey: @clepsydrops<br />
Natee Puttapipat: @Himmapaan<br />
Raven Amos: @alaskanime<br />
Scott Elyard: @notdeadorgone<br />
Scott Hartman: @skeletaldrawing<br />
Talcott Starr: @talcotts<br />
Trish Arnold: @babbletrish<br />
Victoria Arbour: @VictoriaArbour</div>
<br />Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-29139594543621591872018-03-15T16:16:00.003-07:002018-04-16T14:37:24.071-07:00Lesser-Known Running Lizards (minor update at the end)<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP5hC0KbYWCa0qfVD6dyVe7cgn2Zc_W5qlGiiiGLudtXu_JodNZU17EhTZ4OBJN0E5Ho_7NRU60kXzaLHEdMj9tg56Gdw2sx3sVVAZBU-LDrix6UDb6dVkuR-JELJbk_59hh0xud4D4co/s1600/Buitreraptor_gonzalezorum.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="490" data-original-width="1000" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP5hC0KbYWCa0qfVD6dyVe7cgn2Zc_W5qlGiiiGLudtXu_JodNZU17EhTZ4OBJN0E5Ho_7NRU60kXzaLHEdMj9tg56Gdw2sx3sVVAZBU-LDrix6UDb6dVkuR-JELJbk_59hh0xud4D4co/s320/Buitreraptor_gonzalezorum.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">by Jaime Headden, from Wikipedia</td></tr>
</tbody></table>
In the last post, I briefly mentioned a group of
dromaeosaurs called unenlagiines. This is still a rather obscure group,
especially to the general public, so I wanted to give these South American
dromaeosaurs some much-deserved time in the spotlight.<br />
<o:p></o:p></div>
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<br /></div>
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This is a small group—only three (but possibly four or five)
genera have been named. They are atypical dromaeosaurs for a number of reasons,
foremost among them the elongate, narrow snout packed with minute teeth which
lack serrations. While most appear to have been small, one of them was one of the largest dromaeosaurs, approaching <i style="mso-bidi-font-style: normal;">Achillobater</i> and <i style="mso-bidi-font-style: normal;">Utahraptor</i> in terms of overall size.<o:p></o:p></div>
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<a name='more'></a></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9qgSqN6oCic5U7YmOC9qlAZZWWG_k9f0Q3cpuNVT3QPihmmyM3h8baHFYN3Oo4m9JdfazQ0tf4Zd_V0vm6o_C4PlNfIdvFC0x7zRWLED8F3NaD7IuPJS3rv7Qe3umeppzKiwqGLxTFeM/s1600/Unenlagia+comahuensis.bmp" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="723" data-original-width="501" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9qgSqN6oCic5U7YmOC9qlAZZWWG_k9f0Q3cpuNVT3QPihmmyM3h8baHFYN3Oo4m9JdfazQ0tf4Zd_V0vm6o_C4PlNfIdvFC0x7zRWLED8F3NaD7IuPJS3rv7Qe3umeppzKiwqGLxTFeM/s320/Unenlagia+comahuensis.bmp" width="221" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Some pieces of <i>Unenlagia comahuensis</i></td></tr>
</tbody></table>
As you might imagine from the group’s name, the first
unenlagiine to be described was <i style="mso-bidi-font-style: normal;">Unenlagia
comahuensis</i> (<a href="https://www.researchgate.net/publication/232749074_New_evidence_concerning_avian_origins_from_the_Late_Cretaceous_of_Patagonia">Novas & Puerta, 1997</a>). Its remains are quite
fragmentary—the pelvis, left scapula, right leg (missing the foot) and some
vertebrae. Despite this, the authors marveled at how remarkably avian the
scapula was with its laterally-facing glenoid. They suggest that <i style="mso-bidi-font-style: normal;">Unenlagia</i> is representative of a
“proavian” that falls somewhere between Dromaeosauridae and <i style="mso-bidi-font-style: normal;">Archaeopteryx</i>. In 2004, a second species was described, <i style="mso-bidi-font-style: normal;">Unenlagia paynemili</i>, by <a href="https://www.researchgate.net/publication/237421017_On_a_new_maniraptoran_dinosaur_Theropoda_from_the_Upper_Cretaceous_of_Neuquen_Patagonia_Argentina">Calvo, Porfiri& Kellner</a>. Its remains are weirdly similar to <i style="mso-bidi-font-style: normal;">U. comahuensis</i>: elements of the pelvis, a humerus, a dorsal
vertebra, and a toe (with claw). Their phylogenetic analysis recovered <i style="mso-bidi-font-style: normal;">Unenlagia</i> as either in a polytomy with
other dromaeosaurs or as an outgroup of traditional Dromaeosauridae.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br />
<br />
<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdGNdMGy7U2CdmGCZvRjfG7aMatKIrfj1APdXbtvFzBu6Sd3ABlPOtpfUB2rcrIQdLJ7hw8EmwpDdS72NuIo3p_u7xjMTpH0VSDZHF1mfjGLW4d2nnpZQj8enwVWQ_RHH3gnZEtyvGAXU/s1600/Neuquenraptor.bmp" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1109" data-original-width="510" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdGNdMGy7U2CdmGCZvRjfG7aMatKIrfj1APdXbtvFzBu6Sd3ABlPOtpfUB2rcrIQdLJ7hw8EmwpDdS72NuIo3p_u7xjMTpH0VSDZHF1mfjGLW4d2nnpZQj8enwVWQ_RHH3gnZEtyvGAXU/s320/Neuquenraptor.bmp" width="147" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Some pieces of <i>Neuquenraptor</i></td></tr>
</tbody></table>
Another <i style="mso-bidi-font-style: normal;">Unenlagia</i>-like
theropod was described in 2005 by <a href="https://www.researchgate.net/profile/Diego_Pol/publication/8004984_New_evidence_on_deinonychosaurian_dinosaurs_from_the_Late_Cretaceous_of_Patagonia/links/0fcfd501337712b56d000000/New-evidence-on-deinonychosaurian-dinosaurs-from-the-Late-Cretaceous-of-Patagonia.pdf">Novas & Pol</a>: <i style="mso-bidi-font-style: normal;">Neuquenraptor argentines</i>. Sadly, it is even scrappier than <i style="mso-bidi-font-style: normal;">Unenlagia</i>, although an almost complete
foot (including toes and claws) was found. Otherwise it consists of the
proximal half of the left radius, right femur, distal tibia, and fragments of
vertebrae and dorsal ribs. Novas & Pol find <i style="mso-bidi-font-style: normal;">Neuquenraptor</i> and <i style="mso-bidi-font-style: normal;">Unenlagia</i>
in a polytomy with microraptorines and traditional Dromaeosauridae.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
If only a better-preserved unenlagiiine could be found,
right?<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Well, we didn’t have to wait too long. <a href="https://www.researchgate.net/publication/7544544_The_earliest_dromaeosaurid_from_South_America">Makovicky et al</a>. described
<i style="mso-bidi-font-style: normal;">Buitreraptor gonzalezorum</i> that same year. <i style="mso-bidi-font-style: normal;">Buitreraptor</i> finally gives us a
good idea of what these South American dromaeosaurs looked like, and they are
strange. <i style="mso-bidi-font-style: normal;">Buitreraptor</i>’s skull is long
and narrow, with a multitude of tiny teeth which lack serrations, bringing to mind spinosaurs. Interestingly, the humerus is as
long—proportionately—as basal birds and “some dromaeosaurids from Liaoning”
(keep in mind that microraptorans were still new in 2005). The killing
claw, so characteristic of dromaeosaurids, is small and offset medially,
matching <i style="mso-bidi-font-style: normal;">Neuquenraptor</i>, primitive
troodontids, and <i style="mso-bidi-font-style: normal;">Microraptor</i>. This
was not an animal that was going after big game.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLGErBcwQDK1KjRi1CMNONE9ST05oJ56Ab1bn5Lv4QuZIYf1h9uighWP9mG7uT6dAQ6wmaA9bqUlhxLeXCqKZMgQ8PPmPweV5MBCeo3f8Zb0C-eqG0QqwZhFsLUUFdV9Oktkg3nJtMs3Y/s1600/Buitreraptor+Skull.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="999" data-original-width="1600" height="199" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLGErBcwQDK1KjRi1CMNONE9ST05oJ56Ab1bn5Lv4QuZIYf1h9uighWP9mG7uT6dAQ6wmaA9bqUlhxLeXCqKZMgQ8PPmPweV5MBCeo3f8Zb0C-eqG0QqwZhFsLUUFdV9Oktkg3nJtMs3Y/s320/Buitreraptor+Skull.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skull of <i>Buitreraptor</i>, in right lateral view</td></tr>
</tbody></table>
Makovicky et al. formally defined the Unenlagiinae and suggested
that <i style="mso-bidi-font-style: normal;">Unenlagia</i> and <i style="mso-bidi-font-style: normal;">Neuquenraptor</i> may be synonymous, but the
lack of overlapping material makes the situation uncertain. They reference a
“large unnamed deinonychosaurian from the uppermost Cretaceous of Argentina”
which has similar teeth to <i style="mso-bidi-font-style: normal;">Buitreraptor</i>,
which would make the Unenlagiinae quite a long-lived group (<i style="mso-bidi-font-style: normal;">Buitreraptor</i> is from the
mid-Cenomanian). But hey, that giant deinonychosaurian sounds interesting,
doesn’t it? What could that possibly be?<br />
<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3-rUm9oGStIazfYPppd4DdYaWamoypUj11OgZmpOlumu0BvCQMbSjEa4bPMxHGzO4AT-_7XEot3UI4ZmmZk2G7CYFjOk5iiBx9rtCxxTkqeznt73vozJXzuxg_SARJyh_ad7EVoCQeBE/s1600/Austroraptor.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="998" data-original-width="876" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3-rUm9oGStIazfYPppd4DdYaWamoypUj11OgZmpOlumu0BvCQMbSjEa4bPMxHGzO4AT-_7XEot3UI4ZmmZk2G7CYFjOk5iiBx9rtCxxTkqeznt73vozJXzuxg_SARJyh_ad7EVoCQeBE/s320/Austroraptor.jpg" width="280" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Some pieces of <i>Austroraptor</i></td></tr>
</tbody></table>
Turns out it was <i style="mso-bidi-font-style: normal;">Austroraptor
cabazai</i>, described by <a href="http://rspb.royalsocietypublishing.org/content/royprsb/276/1659/1101.full.pdf">Novas et al. in 2009</a>. While fragmentary, <i style="mso-bidi-font-style: normal;">Austroraptor</i> presents a dramatic example
of how diverse the Unenlagiinae must have been. The authors estimate that this
predator was five meters long. While incomplete, the skull is generally similar
to that of <i style="mso-bidi-font-style: normal;">Buitreraptor</i> in being long
and narrow, with a multitude of small, unserrated teeth. Most of the left
hindlimb is preserved. The most surprising thing about <i style="mso-bidi-font-style: normal;">Austroraptor</i> apart from its size is its measly humerus. In stark
contrast to <i style="mso-bidi-font-style: normal;">Buitreraptor</i>, it is quite
short—less than half the length of the femur. Like Makovicky et al., the
authors find a monophyletic Unenlagiinae that sits in a polytomy with
microraptorines and traditional Dromaeosauridae.<o:p></o:p></div>
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A second specimen of <i style="mso-bidi-font-style: normal;">Austroraptor</i>
was described in 2012 by <a href="https://www.researchgate.net/publication/249992730_A_New_Specimen_of_Austroraptor_cabazai_Novas_Pol_Canale_Porfiri_and_Calvo_2008_Dinosauria_Theropoda_Unenlagiidae_from_the_Latest_Cretaceous_Maastrichtian_of_Rio_Negro_Argentina">Currie & Carabajal</a>. Although even more fragmentary
than the holotype, this second specimen preserves different bones, allowing a
better overall picture of <i style="mso-bidi-font-style: normal;">Austroraptor</i>;
for example, a complete right ulna and left radius and many foot and toe
elements, including claws. <i style="mso-bidi-font-style: normal;">Austroraptor</i>
still had a very short forelimb, but the proportions of the humerus to the
forearm are more typical for dromaeosaurs. <i style="mso-bidi-font-style: normal;">Austroraptor</i>
would have lived alongside derived abelisaurs, which is a neat image.<o:p></o:p></div>
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Andrea Cau has suggested that <i style="mso-bidi-font-style: normal;">Austroraptor</i> is not related to <i style="mso-bidi-font-style: normal;">Buitreraptor</i>
but is, instead, <a href="http://theropoda.blogspot.com/2008/12/austroraptor-atto-secondo-unenlagiino-o.html">a giant troodontid</a> which I’d also be okay with.<o:p></o:p></div>
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<a href="https://www.app.pan.pl/article/item/app003482017.html">Brisson Egli et al. (2017)</a> tried to figure out whether <i style="mso-bidi-font-style: normal;">Unenlagia</i> and <i style="mso-bidi-font-style: normal;">Neuquenraptor</i> are synonymous or not by providing a detailed osteology of
the latter. Sadly, the jury is still out. Of the few overlapping elements, the
distal ends of their tibiae seem to differ in degree of gracility, and the
proportions of the shared pedal phalanges are of slightly different proportions
between the two.<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIyQqLcz6hajrOGgPtPBn4UMb2yB-GFeY_y-fmcpGYE9oti9c35vG_tYPaB3iGFvzmOyBc5n-FrWctAPUFepa7zVC-POU1QvtBYo-mYuGaYMuZyUM5YxVRCtCSHSKwyi4cxWIAUhTPCZA/s1600/Pamparaptor.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="488" data-original-width="793" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIyQqLcz6hajrOGgPtPBn4UMb2yB-GFeY_y-fmcpGYE9oti9c35vG_tYPaB3iGFvzmOyBc5n-FrWctAPUFepa7zVC-POU1QvtBYo-mYuGaYMuZyUM5YxVRCtCSHSKwyi4cxWIAUhTPCZA/s320/Pamparaptor.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The foot of <i>Pamparaptor</i></td></tr>
</tbody></table>
Another potential unenlagiine, <i style="mso-bidi-font-style: normal;">Pamparaptor</i>, was described in <span style="background-color: white;">2011</span> by <a href="http://www.scielo.br/pdf/aabc/v83n1/v83n1a07.pdf">Porfiri, Calvo & dosSantos</a>. Originally referred to <i style="mso-bidi-font-style: normal;">Neuquenraptor</i>,
the holotype comprises only of a partial foot. The foot shows dromaeosaurid and
troodontids characteristics, and the authors reject both the idea that <i style="mso-bidi-font-style: normal;">Pamparaptor</i> might be synonymous with <i style="mso-bidi-font-style: normal;">Neuquenraptor</i> and that <i style="mso-bidi-font-style: normal;">Neuquenraptor</i> and <i style="mso-bidi-font-style: normal;">Unenlagia</i> are synonymous. For reasons I’m not completely sure of,
they conclude that this invalidates <a href="http://digitallibrary.amnh.org/handle/2246/6352">Turner et al’s (2012)</a> Unenlagiinae
and that South America’s dromaeosaurs are still in a polytomy.<br />
<o:p></o:p></div>
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Finally, you can’t spell “Unenlagiinae” with “<i style="mso-bidi-font-style: normal;">Rahonavis</i>.” This tiny Malagasy paravian,
described in 1998 by <a href="http://www.academia.edu/24083616/The_Theropod_Ancestry_of_Birds_New_Evidence_from_the_Late_Cretaceous_of_Madagascar">Forster et al.</a>, has been kicked around the Paravian family
tree ever since. Its partial skeleton presents a maddeningly ambiguous
dinobird. Of the arm, only the ulna and radius were found, but they are
proportionately quite long and the ulna bears quill knobs. The pelvis
resembles that of both <i style="mso-bidi-font-style: normal;">Archaeopteryx</i>
and <i style="mso-bidi-font-style: normal;">Unenlagia</i>, and the sacrum is
composed of six co-ossified vertebrae (one more than <i style="mso-bidi-font-style: normal;">Archaeopteryx</i>). The femur resembles that of <i style="mso-bidi-font-style: normal;">Archaeopteryx</i> and more derived birds in that the fibula does not contact
the calcaneum. A complete, articulated foot, missing only the claws of Digits
III & IV, show a reversed hallux and a (proportionately) large sickle claw
on Digit II, which was hyperextended when discovered.<o:p></o:p><br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw_SQ6qiMxew4154x2XVYKkREfP2_FShbscZH8kOB5fzxTKV2pppj9piHnon0ZtbyC2PtAUnBX_fw1m2GDF-6Sae0InseiN6lYTDEUNmPfLuHYvrGcD25VS6yxZ7HMCtIGb40hfFiDIZ4/s1600/Rahonavis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="971" data-original-width="621" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw_SQ6qiMxew4154x2XVYKkREfP2_FShbscZH8kOB5fzxTKV2pppj9piHnon0ZtbyC2PtAUnBX_fw1m2GDF-6Sae0InseiN6lYTDEUNmPfLuHYvrGcD25VS6yxZ7HMCtIGb40hfFiDIZ4/s320/Rahonavis.jpg" width="204" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Some pieces of <i>Rahonavis</i></td></tr>
</tbody></table>
Forster et al. ran a phylogenetic<span style="mso-spacerun: yes;"> </span>analysis and <i style="mso-bidi-font-style: normal;">Rahonavis</i> wound up in a monophyletic clade with <i style="mso-bidi-font-style: normal;">Archaeopteryx</i> and <i style="mso-bidi-font-style: normal;">Unenlagia</i>. However, the clade is not robustly supported. I should
note here that, in 1998, <i style="mso-bidi-font-style: normal;">Buitreraptor</i>
was unknown and alvarezsaurids were thought to be basal flightless birds.</div>
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<o:p></o:p></div>
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Concerns have been raised that the <i style="mso-bidi-font-style: normal;">Rahonavis</i> holotype might represent a chimaera, as the arm bones
(scapula, ulna & radius) are not in articulation with the rest of the
specimen. Forester et al. recognized this possibility but were confident that all the bones
belong to a single individual. <a href="http://theropoda.blogspot.com/2009/01/le-cronache-di-deinonychosauria-terza.html">Andrea Cau</a> ran the arm bones alone through his
matrix separately from the rest of the skeleton, and they wind up in completely
different places: “Rahonavis Wing” is right next to enantiornithines, whereas
the rest of it is next to <i style="mso-bidi-font-style: normal;">Mahakala</i>
(which we now know is a halszkaraptorine).<o:p></o:p></div>
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Turner et al. (2012) found <i style="mso-bidi-font-style: normal;">Rahonavis </i>to be a member of the Unenlagiinae and a sister taxon to <i style="mso-bidi-font-style: normal;">Unenlagia</i>. <a href="http://science.sciencemag.org/content/sci/317/5843/1378.full.pdf">Turner et al. (2007)</a> got the
same result in their description of <i style="mso-bidi-font-style: normal;">Mahakala</i>.
As we saw in the anchiornithid post, though, more current phylogenies have
moved <i style="mso-bidi-font-style: normal;">Rahonavis</i> back to a position
among basal birds. I suspect that until we have more complete remains from an
unambiguously single animal, its position will continue to jump
around—especially if Andrea is right and <i style="mso-bidi-font-style: normal;">Rahonavis</i>
is a chimaera. And so, that familiar refrain: we need more specimens to clarify what, exactly, <i>Rahonavis</i> is.<br />
<br />
In 2011, <a href="http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000100008">Agnolin & Novas</a> published an interesting phylogenetic analysis of Unenlagiidae in which they find the group as outside of Dromaeosauridae and, in fact, Deinonychosauria. Instead, Unenalagiines are the basalmost group of birds, forming an outgroup to <i>Archaeopteryx</i> + everyone else. Their analysis includes <i>Rahonavis</i> as an unenlagiine but they acknowledge that more detailed analyses may deposit it elsewhere in the phylogeny. Of course, this unique topology is in contrast to the standard tree, as might be exemplified by Turner, et al. (2012), in which Unenlagiinae is a basal group of dromaesaurs. Agnolin & Novas followed up their 2011 analysis with a <a href="https://www.researchgate.net/publication/316817425_Avian_Ancestors">much larger analysis in 2013</a>. They again find unenlagiines to be essentially the outgroup of Avialae. They do remove <i>Rahonavis</i> from Unenlagiinae, though, and deposit it among basal birds, in a more derived position than <i>Archaeopteryx</i>.<br />
<br />
More recently, <i>Buitreraptor</i> has received the monograph treatment in three parts: the <a href="https://www.tandfonline.com/doi/abs/10.1080/02724634.2017.1255639">skull</a>, the <a href="https://www.researchgate.net/publication/319607588_Tail_anatomy_of_Buitreraptor_gonzalezorum_theropoda_unenlagiidae_and_comparisons_with_other_basal_paravians">tail</a>, and the <a href="https://www.sciencedirect.com/science/article/pii/S0195667117300678">body</a>. Turns out it has ridiculously long, spindly fingers. In general, <i>Buitreraptor</i> is similar to dromaeosaurids, troodontids, <i>Archaeopteryx</i>, and even <i>Anchiornis</i> in several features. This is not terribly surprising considering that unenlagiines are close to the origins of paravians generally. Still, it would be interesting to know how--if at all--this full description of <i>Buitreraptor</i> shakes up Agnolin & Novas' suggestion that unenlagiines are not dromaeosaurs.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3YVDLD8QENwDbaWjE2sboVzvTLAmuirRRoXWTmPDBVXaftbIqHd4jBhBdNcp8bEe6EYp4fPh-N3Jn3bWQkpx8HxDuGxYZ3M1MwXjPnq45ggOvouItBourR9eMvvnBBir9PaF2ZYAiC_M/s1600/Buitreraptor+Skeleton.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="511" data-original-width="1600" height="127" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3YVDLD8QENwDbaWjE2sboVzvTLAmuirRRoXWTmPDBVXaftbIqHd4jBhBdNcp8bEe6EYp4fPh-N3Jn3bWQkpx8HxDuGxYZ3M1MwXjPnq45ggOvouItBourR9eMvvnBBir9PaF2ZYAiC_M/s400/Buitreraptor+Skeleton.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">From Novas et al. (2018): a very strange dromaeosaur, indeed.</td></tr>
</tbody></table>
I'm sure there's plenty more unenlagiine material left to be found in South America, and I'll be interested to see how this group fills out in the future.<br />
<br />
I'm pushing this post out the door even though I'm not 100% happy with it because I really need to post something. Maybe placodonts next month! Cross your fingers.<br />
<br />
UPDATE: A second paper on the postcranial osteology of <i>Buitreraptor</i>, based on both the holotype and referred specimens, was recently published by <a href="https://peerj.com/articles/4558/">Gianichini et al.</a> in PeerJ. Unlike Agnolin & Novas, above, they find that unenlagiines are perfectly good dromaeosaurs. Another interesting tidbit is that their phylogeny recovers <i>Mahakala</i> as an outgroup to the Unenlagiinae, which supports halszkaraptorines as basal dromaeosaurids, possibly allied closely with unenlagiines.</div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-43953775284081237222018-01-30T15:52:00.003-08:002018-01-30T15:52:33.939-08:00Nearly Birds<div class="MsoNormal">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6SGgMpQ7Rn2Dx1-KlmSc42imZI0o6FWCkFomEBDKj2jGGNQjL2s6P-uEikoOWoMTDWq4okRMw3Y8r8Odzk6Wm8cceAcSGSkQzByC4L22wNvfu9aUyUbnskNWq_EZV28HVCMefcw7aqI/s1600/Serikornis+Header.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="837" data-original-width="1200" height="223" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6SGgMpQ7Rn2Dx1-KlmSc42imZI0o6FWCkFomEBDKj2jGGNQjL2s6P-uEikoOWoMTDWq4okRMw3Y8r8Odzk6Wm8cceAcSGSkQzByC4L22wNvfu9aUyUbnskNWq_EZV28HVCMefcw7aqI/s320/Serikornis+Header.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adorable <i>Serikornis sungei</i> by Emily Willoughby</td></tr>
</tbody></table>
Something I really enjoy about paleontology is how quickly
things can change. For example, when I was growing up, Dromaeosauridae was
confined to half a dozen genera from two continents. If you wanted a complete
list, you could check out <u><a href="https://www.amazon.com/Raptors-Nastiest-Dinosaurs-Don-Lessem/dp/0316521191">Raptors: The Nastiest Dinosaurs</a></u> from your
local library. Now, though, Dromaeosauridae is more like Dromaeosauriformes
because there are something like five distinct groups now: Halszkaraptorinae,
Unenlaginae, Microraptorinae, Dromaeosaurinae and Velociraptorinae (those last
two are usually stuck together in a monophyletic Eudromaeosauria). It used to
be that dromaeosaurs came in two flavors: large and small. Now you’ve got
swan-necked, duck-billed dromaeosaurs; piscivorous, leggy dromaeosaurs; tiny,
potentially volant dromaeosaurs; and larger “classic” predatory dromaeosaurs.<br />
<o:p></o:p></div>
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All this has happened in the last twenty years. Heck, nobody
knew about <i><a href="https://www.nature.com/articles/nature24679">Halszkaraptor</a></i> until a few
weeks ago.<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Ov9cizUKPhTDdcs5sJY0LMZFzPvYCbt5SPhFzbml6YG6kggDwmpwG58iWdElOaH17UjQ2QusxBbQ23I4kAJN0DnZMurA9Xdtgsezx4kKiF77w0CSoU09u9o1ikudPh2pI8a4AoDLfVA/s1600/Anchiornis+1.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="489" data-original-width="367" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Ov9cizUKPhTDdcs5sJY0LMZFzPvYCbt5SPhFzbml6YG6kggDwmpwG58iWdElOaH17UjQ2QusxBbQ23I4kAJN0DnZMurA9Xdtgsezx4kKiF77w0CSoU09u9o1ikudPh2pI8a4AoDLfVA/s320/Anchiornis+1.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The holotype of <i>Anchiornis huxleyi</i></td></tr>
</tbody></table>
For several years now, paleontologists in China have been
digging up theropods that seem to toe the line between “bird” and “non-avian
dinosaur.” And many of them are, critically, older than <i>Archaeopteryx</i>. The first of these to be described was <i>Anchiornis huxleyi</i>, named in 2009 by <a href="http://www.ivpp.ac.cn/qt/papers/201403/P020140314379333425828.pdf">Xuet al.</a> The first described specimen (IVPP V14378) lacked a head and most of the
right arm but was otherwise quite complete. Feathers were present but weren’t
all that special: “Specifically, extremely faint carbonized feather impressions
are preserved dorsal to the presacral vertebral column…but their detailed
structure is not clear.” The authors placed <i>Anchiornis</i>
right below <i>Archaeopteryx</i>,
phylogenetically.<br />
<br />
I'm not sure why I'm including specimen numbers in this essay, but I kinda like it.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWvAAJT1GsL3_7VqYRaS2RyiAzxTkQBBmRfqktrXOH0QzindEk9jyLC9PFilJr3Ro7daKnieXkgHHUXdsj0ShcD658k_Tv4tT-FmarFc-9wMKOY62DsVEdrI3kMlPgYGk4aI0u3x4DnoE/s1600/Anchiornis+2.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="987" data-original-width="1039" height="303" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWvAAJT1GsL3_7VqYRaS2RyiAzxTkQBBmRfqktrXOH0QzindEk9jyLC9PFilJr3Ro7daKnieXkgHHUXdsj0ShcD658k_Tv4tT-FmarFc-9wMKOY62DsVEdrI3kMlPgYGk4aI0u3x4DnoE/s320/Anchiornis+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A much better specimen of <i>Anchiornis huxleyi</i></td></tr>
</tbody></table>
Well, it turns out there are many more specimens of <i>Anchiornis</i> out there, both in museums
and in private hands, and later that same year, a much more complete specimen was described
in <u>Nature</u> by <a href="https://www.researchgate.net/publication/26861082_A_pre-Archaeopteryx_troodontid_theropod_from_China_with_long_feathers_on_the_metatarsus">Hu et al.</a> This new specimen (LPM-B00169) provides a much
more dramatic picture than the holotype did. <i>Anchiornis</i> is a crow-sized dinobird with long feathers not just on
its tail, hands and arms but also on its legs and feet. Hindwings were old news
thanks to <i>Microraptor</i>, but feathered
feet and toes were new. The authors ran <i>Anchiornis</i>
through a phylogenetic analysis (like you do) and found <i>Anchiornis</i> to be the basalmost troodontid (by almost 40 mya), but also
that it shares features in common with troodontids, basal birds, and basal dromaeosaurs,
indicating that <i>Anchiornis</i> seems to
be right at the divergence point for birds and deinonychosaurs.<br />
<br />
Also, the
Tiaojishan Formation where <i>Anchiornis</i>
is found turns out to be older than <i>Archaeopteryx</i>
by up to 10 mya.<o:p></o:p></div>
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<br /></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKcLoZexl_piHsqsspeLqeV7Vks71O7s02ZoCOheehP5lMaMJxP_rK9jLBpTrrKuHXRYtSxlFDqaos_1xmlBAxJF_OxRZzxc2CAVY2fgSSj1dzlBCSiVoeuBpqk-2T5HlNMHkqmi1i9B4/s1600/Xiaotingia.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1383" data-original-width="1418" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKcLoZexl_piHsqsspeLqeV7Vks71O7s02ZoCOheehP5lMaMJxP_rK9jLBpTrrKuHXRYtSxlFDqaos_1xmlBAxJF_OxRZzxc2CAVY2fgSSj1dzlBCSiVoeuBpqk-2T5HlNMHkqmi1i9B4/s320/Xiaotingia.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Xiaotingia zhengi</i></td></tr>
</tbody></table>
Next up to the near-bird plate is <i>Xiaotingia zhengi</i>, described in 2011 by <a href="http://www.ivpp.ac.cn/qt/papers/201403/P020140314389417822583.pdf">Xu et al.</a> It is also a
small animal (STM 27-2) from Tiaojishan with faint feather impressions around
the whole skeleton, but like <i>Anchiornis</i>,
has elongated feathers on its leg and small feathers on the toes. Unlike Hu et
al. (2009), who focused on comparisons between <i>Anchiornis</i> and troodontids, Xu et al. (2011) make many comparisons
between <i>Xiaotingia </i>and <i>Archaeopteryx</i>, with fewer comparisons to
<i>Anchiornis</i>. </div>
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<br /></div>
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This paper caused a bit
of a stir in the paleo community because the authors’ phylogenetic analysis
actually removed <i>Archaeopteryx</i> from
Avialae. Instead, <i>Archaeopteryx</i> is
now in a group with <i>Anchiornis</i> and <i>Xiaotingia</i>, which is a sister group of
Deinonychosauria. This large group, then, is the sister of Avialae. Xu et al.
(2011) comment that basal birds like <i>Sapeornis</i>,
<i>Jeholornis</i>, and <i>Epidexipteryx</i> (which they seem to think is a basal bird) are “more
similar in general morphology to the oviraptorosaurs than to the
archaeopterygids and basal deinonychosaurs.”<o:p></o:p></div>
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<br /></div>
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While the removal of <i>Archaeopteryx</i>
from Avialae has not withstood subsequent testing, the idea that <i>Anchiornis</i> and <i>Xiaotingia</i> form a monophyletic group will come up again.<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFnwmgyW-sIHydW9VJgwRatWtjWf6xQ9fzk64MMbmkgalrlRjqwmnZZYXRZa_1rdrZZoZD482nx6j7Xoz6wNTafJWlSai3muETJR-doPhUGVg9-boEWhP_LDEMdW0yN_45vAj4AcyVJYE/s1600/Eosinopteryx.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1086" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFnwmgyW-sIHydW9VJgwRatWtjWf6xQ9fzk64MMbmkgalrlRjqwmnZZYXRZa_1rdrZZoZD482nx6j7Xoz6wNTafJWlSai3muETJR-doPhUGVg9-boEWhP_LDEMdW0yN_45vAj4AcyVJYE/s320/Eosinopteryx.jpg" width="217" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Eosinopteryx brevipenna</i></td></tr>
</tbody></table>
2013 saw the publication of two more near-birds, both, of
course, from Tiaojishan: <i>Eosinopteryx
brevipenna</i> (YFGP-T5197) is the first, described by <a href="https://www.nature.com/articles/ncomms2389">Godefroit et al. (2013a)</a>
in <u>Nature</u>. Like its cousins, it has elongate feathers on its hands,
arms, and legs but, notably, feathers seem to be absent on the metatarsus and
toes. Tail feathers are short, which is not the case in some of the other
near-bird taxa we’ll discuss. While <i>Eosinopteryx</i>
is smaller than <i>Anchiornis</i> or <i>Xiaotingia</i>, it appears to have died as
either a subadult or adult, so Godefroit et al. (2013a) do not believe that the
lack of a complete hindwing is ontogenetic. Their phylogeny, however, puts <i>Anchiornis</i>, <i>Xiaotingia</i>, and <i>Eosinopteryx</i>
back at the base of Troodontidae while leaving <i>Archaeopteryx</i> (and <i>Wellnhoferia</i>—a
topic for another day) at the base of the Deinonychosauria. This major group is,
again, a sister to Avialae.<br />
<br />
Godefroit et al. (2013a) posit that <i>Eosinopteryx</i> was more terrestrial than its cousins, both
because of the featherless metatarsus and feet and its smaller wings.
Interestingly, they note that <i>Anchiornis</i>
and <i>Eosinopteryx</i> are very similar
osteologically but clearly differ in terms of plumage. We may come back to this
point later.</div>
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<o:p></o:p></div>
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<br /></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTdQ3Jt8eo1oYdIA6jvAHph8aFmtDK7OTWgAwzkBpVGZ7nfarRvYAQpH8RQHE2I9XCxNLKgUCIkdP6OHxwspE77B55zIQDVM6PikRuJsV2zBu-FzUZ3hM1_yUkzfMpRWYOToyhwBZTytM/s1600/Aurornis.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="789" data-original-width="1389" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTdQ3Jt8eo1oYdIA6jvAHph8aFmtDK7OTWgAwzkBpVGZ7nfarRvYAQpH8RQHE2I9XCxNLKgUCIkdP6OHxwspE77B55zIQDVM6PikRuJsV2zBu-FzUZ3hM1_yUkzfMpRWYOToyhwBZTytM/s320/Aurornis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Aurornis xui</i></td></tr>
</tbody></table>
And then, not too much later, <a href="https://pdfs.semanticscholar.org/14d5/732dbec926f3df33f23eef2fb58ed2dc4131.pdf">Godefroit et al. (2013b)</a>
described <i>Aurornis xui</i>. While
feathers are not very well preserved on this specimen (YFGP-T5198), the
skeleton is certainly in better shape than <i>Xiaotingia</i>
and it looks a whole lot like <i>Eosinopteryx</i>. Can you guess where it's from? That's right, kids, Tiaojishan. There’s not too much to say about its anatomy that hasn’t already been said
about its brethren, but the main takeaway (for me) is that their new
phylogeny shuffles the all these basal paravians around again. None of the
previously-described near-birds are troodontids anymore. Instead, <i>Eosinopteryx</i> is the ougroup of Paraves and everyone else forms a stepwise
progression within Avialae in this order: <i>Aurornis</i>,
<i>Anchiornis</i>, <i>Archaeopteryx</i>, <i>Xiaotingia</i>,
and then all other birds.<br />
<o:p></o:p></div>
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<br /></div>
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But it’s clear that nobody can agree who is actually related
to whom because all of these near-birds are so much alike. Frustrating, right?<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0hK2xuocxcTP3BVD0aViGjqoXvpTnKDHLKgtSE8Nv69x7O_jvj4YpV4-ph5nE4mCHv2YU3m9A5DuJMq0NBPCukpw4yH_vM6F5DLLGZwUTwtzZvj1V-rrGeedyxHZ5Iqka8kd7077BRhY/s1600/Anchiornis+3.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1195" data-original-width="1600" height="239" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0hK2xuocxcTP3BVD0aViGjqoXvpTnKDHLKgtSE8Nv69x7O_jvj4YpV4-ph5nE4mCHv2YU3m9A5DuJMq0NBPCukpw4yH_vM6F5DLLGZwUTwtzZvj1V-rrGeedyxHZ5Iqka8kd7077BRhY/s320/Anchiornis+3.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A way, WAY better specimen of <i>Anchiornis huxleyi</i></td></tr>
</tbody></table>
During all this time, <i>Anchiornis</i>
was quietly becoming super well-known in terms of osteology, <a href="https://www.nature.com/articles/ncomms14576">soft</a>-tissue, and <a href="http://onlinelibrary.wiley.com/doi/10.1111/pala.12342/full">plumage</a>.
In 2017, <a href="http://digitallibrary.amnh.org/handle/2246/6707">Pei et al.</a> described four beautiful new specimens of <i>Anchiornis</i> in a gorgeous monograph that
you should all read if only for the jaw-dropping photos. Those authors confirm that <i>Anchiornis</i> is a lot like the other Tiaojishan near-birds (surprise!), and that it
shares many features with <i>Archaeopteryx</i>
that are not found in deinonychosaurs. As for its troodontids characteristics,
Pei et al. find those to simply be more commonly distributed among basal
paravians and are not unique to troodontids, so there's no good reason to call them troodontids. The authors suggest that <i>Anchiornis</i> is a basal avialan and,
furthermore, that the Tiaojishan near-birds “likely form a monophyletic group based
on their anatomical similarities.” Interestingly, Pei et al. (2017) regard <i>Aurornis</i> as a junior synonym of <i>Anchiornis</i> but <a href="http://theropoda.blogspot.com/2017/04/aurornis-e-sinonimo-di-anchiornis.html">Andrea Cau has debated that</a>.</div>
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<o:p></o:p></div>
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<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgF0YHeAXmOwb7ov8425_XHRSKysVpmLwREkoNvBf1BdJwA5KtRCpCka_OHbQuSD-oa9IUJ7nplp-StNv1uMz2dv7sdWuRkZqqs3wVn81rJbVL7PjViPF_98Wgaxq1J2H-gQxB7CAtdU9Y/s1600/Serikornis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1115" data-original-width="1527" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgF0YHeAXmOwb7ov8425_XHRSKysVpmLwREkoNvBf1BdJwA5KtRCpCka_OHbQuSD-oa9IUJ7nplp-StNv1uMz2dv7sdWuRkZqqs3wVn81rJbVL7PjViPF_98Wgaxq1J2H-gQxB7CAtdU9Y/s320/Serikornis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Serikornis sungei</i></td></tr>
</tbody></table>
Yet another near-bird was described in the middle of 2017 by
<a href="https://link.springer.com/epdf/10.1007/s00114-017-1496-y?author_access_token=qK5jILmlXqTUfzaXSeOT4fe4RwlQNchNByi7wbcMAY5XtMiIuzLHT0w7pfMEQCqN57cyEs2GIzoqs5Z9sbEt05ydpRV-wedb1KJ5MwJh8Kg2RuubzDV9r0AJl8jBoI_iqK1-9ikzq8p8bOLVXyh_UA%3D%3D">Lefevre et al.</a> <i>Serikornis sungei</i> is
yet another small Tiaojishan taxon (PMOL AB00200). While also quite small, <i>Serikornis</i> differs considerably from its
cousins in the fine details of its skeleton but also its proportions and
plumage. It would seem that all of these near-birds were covered with a
surprising variety of feather types, and that their lack of unambiguously
scansorial or arboreal adaptations suggests they were largely terrestrial. In
their phylogeny, Lefevre et al. (2017) find that <i>Aurornis</i>, <i>Eosinopteryx</i>,
and <i>Serikornis</i> form a monophyletic
outgroup of traditional Paraves, and <i>Anchiornis</i>
is the basalmost paravian. What about <i>Xiaotingia</i>?
Their results oddly place that taxon in the Scansoriopterygidae but “its
position is highly unstable and further investigations are required to fix its
position.”</div>
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<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
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Then, at the end of 2017, <a href="https://link.springer.com/article/10.1186/s12862-017-1076-y">Foth & Rauhut</a> took a closer
look at the Haarlem <i>Archaeopteryx</i> fossil and realized that it’s probably not an urvogel, but an anchiornithid
instead, which they named <i>Ostromia
crassipes</i>. Furthermore, they actually give a name to this group of
near-birds for the first time: Anchiornithidae. Their phylogenetic analysis does, in fact, place <i>Anchiornis</i> within the Anchiornithidae
(contra Lefevre et al. 2017) which includes all the other near-birds I’ve been
discussing plus <i>Ostromia</i>, of course.
Interestingly, they find that <i>Epidexipteryx</i>
is not just an avialan, but is one step higher than <i>Archaeopteryx</i>! </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
(you know, what we really need are more, and better
preserved, scansoriopterygian fossils)<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
It’s also notable that <i>Ostromia</i>
is the first anchiornithid to be found outside of China, although another one
may be described before too long based on Scott Hartman’s SVP talk…<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1O-1JKL8L5rVYK5o2_NaB7yj1yX2hhIYkMlxlg6vF-2uiD9FLMfVcMcIdEepLqgauVprP3p8gw6FRQb1xLF6bF41tvFtUTumAHu-nzZaSK8YH9VKRVuYuXC300y8lHCabp8TGL7GkKbo/s1600/Caihong.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1299" data-original-width="1600" height="259" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1O-1JKL8L5rVYK5o2_NaB7yj1yX2hhIYkMlxlg6vF-2uiD9FLMfVcMcIdEepLqgauVprP3p8gw6FRQb1xLF6bF41tvFtUTumAHu-nzZaSK8YH9VKRVuYuXC300y8lHCabp8TGL7GkKbo/s320/Caihong.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Caihong juji</i></td></tr>
</tbody></table>
And now, just last week, another small Tiaojishan near-bird
came out of the pipeline—<i>Caihong juji</i>
is the most divergent of the group (<a href="https://www.nature.com/articles/s41467-017-02515-y">Hu et al. 2018</a>) (PMoL-B00175). Its skull is
elongate, looking more like <i>Velociraptor</i>
than <i>Anchiornis</i>. It may or may not
have lacrimal horns (they might be a distortion artifact). Its arms are
proportionately shorter than other Tiaojishan theropods but, weirdly, the ulna
and radius are proportionately longer. In fact, it is longer than the humerus,
“a feature so far known only in flighted avialan taxa among theropods.”<br />
<o:p></o:p></div>
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<br /></div>
<div class="MsoNormal">
<br />
Beautiful feather impressions surround the whole body. <i>Caihong</i>’s wing feathers are much longer
than <i>Anchiornis</i> and it appears to
have an alula. Its leg feathers are also quite long, and like <i>Anchiornis</i> it has feathers on its
metatarsus and toes. The authors note that:<br />
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="margin-left: .5in;">
<i>Eosinopteryx
brevipenna</i> has been suggested to have reduced tail and hindlimb plumages,
but specimens of <i>Anchiornis huxleyi</i>
display variable plumages in terms of not only feather distribution, but also
feather size and shape. Some closely related Tiaojishan theropods not
differentiated by osteological features may need reassessment of their
taxonomic status.<o:p></o:p></div>
<div class="MsoNormal" style="margin-left: .5in;">
<br /></div>
<div class="MsoNormal">
I'm not sure any of these Tiaojishan anchiornithids have been described as identical apart from plumage differences. The tail feathers of <i>Caihong</i>
are particularly long and, like the basal troodontids <i><a href="https://www.nature.com/articles/ncomms14972">Jianianhualong</a></i>, appear to be asymmetrical; this is especially
strange given that the wing and leg feathers are not. Like <i>Serikornis</i>, <i>Caihong</i>
features a wide variety of feather types on its body. Its preserved melanosomes
suggest that <i>Caihong</i> was mostly
black, but featured hummingbird-like iridescence on its head, chest, and
possibly the base of the tail. The only other iridescent dinobird I know of is <i>Microraptor</i> (<a href="https://projects.ncsu.edu/cals/course/zo501/Other%20Articles/Microraptor%20Feathers%202012.pdf">Lu et al. 2012</a>), but its
melanosomes were not directly compared to hummingbirds. The implication
of Hu et al. (2018) is that <i>Caihong</i>
was colorful--moreso than its contemporaries, anyway.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
The authors’ phylogenetic study resembles that of Xu et al.
(2011) in that <i>Archaeopteryx</i> is
removed from Avialae and instead forms an outgroup to Anchiornithidae +
Deinonychosauria. However, all of the anchiornithids are found to be
monophyletic.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqhkUcVZfF4RQIrbFvFOLIFcCFenaspiMzh0WVIvIyZoQmEgzhQ2BUygo7uqZcIZkr2bG1AexD_EAf0BLHRMiPc1VZumSOZWRsvOxpKQD27TiQd77AjVpS50ttqvkpsJIRaT6m_IiS6MY/s1600/Anchiornis+4.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="819" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqhkUcVZfF4RQIrbFvFOLIFcCFenaspiMzh0WVIvIyZoQmEgzhQ2BUygo7uqZcIZkr2bG1AexD_EAf0BLHRMiPc1VZumSOZWRsvOxpKQD27TiQd77AjVpS50ttqvkpsJIRaT6m_IiS6MY/s320/Anchiornis+4.jpg" width="163" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Rebecca Gelernter's <i>Anchiornis</i></td></tr>
</tbody></table>
And that's where things currently stand. Another interesting thing about Tiaojishan is that it seems to be dominated by pterosaurs and small mammals. Aside from the animals discussed here, the only other dinosaurs present are all three scansoriopterygian taxa and <i>Tianyulong</i>, the fluffy heterodontosaur. Where are all the other dinosaurs? Tiaojishan is older than the famous Yixian Formation, which is where every other famous feathered dinosaur is from. That there are no deinonychosaurs or avialans at Tiaojishan seems to support the idea that anchiornithids predate the divergence of both.<br />
<br />
Another oddity is that there apparently hundreds of specimens of <i>Anchiornis</i> available for study but every other Tiaojishan anchiornithid is known from a single specimen. What made <i>Anchiornis</i> so successful compared to its neighbors? How capable were these animals from an aerodynamic angle? Did they make frequent trips up tree trunks and then glide back down or between trees? The extreme feathering on the legs and feet of several anchiornithids doesn't seem terribly useful in a terrestrial context. Rebecca Gelernter restores <i>Anchiornis</i> in a hypothetical branch-climbing pose, but would it have been able to do this in life? Would any anchiornithid? Besides, with an apparently lack of carnivores to run from, would anchiornithids feel any pressure to get off the ground at all? How did they interact with the numerous pterosaurs and small mammals who were their neighbors?<br />
<br />
Whatever the answers may be, I suspect that anchiornithids have much to tell us about the origin of birds, modern plumage, and (maybe) flight. And with such beautiful fossils coming out of Tiaojishan, the answers may be closer than we think.<br />
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Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-68691567152493508012017-12-13T23:26:00.000-08:002017-12-14T20:27:23.839-08:00Chilesaurus and Avian Arm Folding<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5ZbLIbttHzICsMyPPZKLrVlup89hxHywkykn_aacpUX9VDQFSP4ZKj4iMiklQtf089gdws4avXR2t0jqM5L2i62mZ7-ikpQpu__G1m53tDn-SN3dNtHrBUCNkpqpAiY8MlsMqk5JT2ZQ/s1600/Chilesaurus+Skeletal.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="518" data-original-width="1000" height="165" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5ZbLIbttHzICsMyPPZKLrVlup89hxHywkykn_aacpUX9VDQFSP4ZKj4iMiklQtf089gdws4avXR2t0jqM5L2i62mZ7-ikpQpu__G1m53tDn-SN3dNtHrBUCNkpqpAiY8MlsMqk5JT2ZQ/s320/Chilesaurus+Skeletal.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Chilesaurus diegosuarezi</i> by the impeccable Jaime Headden</td></tr>
</tbody></table>
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Ever since the publication of supreme oddball <i>Chilesaurus</i> (eat your heart out, <i>Halszkaraptor</i>), I’ve been dying for
somebody out there to do a full description of the critter’s unusual skeleton.
As <i>Chilesaurus </i>may hold the key to our
understanding of early ornithischians (or not), this is an animal in dire need
of detailed study. This past Sunday, a paper was published in a journal that I
can’t pronounce—<i>Ameghiniana</i>—and it is
not that description. However, it is very interesting, and since I imagine many
of you don’t have access to, uh, Ameg-HEE-ana (?), I thought I might summarize
the juicy parts here.</div>
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Authored by Chimento et al. (2017), this paper discusses the
forelimb posture of <i>Chilesaurus</i>. I
was not aware of this, probably because I didn’t read the supplementary
information in the initial description of <i>Chilesaurus</i>,
but out of the six specimens found, four of them have good forelimb material. In
all cases, the forelimbs are strongly flexed—the elbow is tightly folded and,
surprisingly, the hand is flexed to a degree we usually associate with
maniraptors. This is especially evident in specimen SNGM-1937.<o:p></o:p></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDnJydBaJJkxGj29seU73ZWE7A5kAq6CYtrRQSqi7Ugm_Es82fa34gnnjVt-x1e4_jaUimUSgtWpi90Sjhg3WrQTegzhIWiwdmK4_oJJ1ypwjysNwg_7K_vDHtBNoKna0ivBIom_bENoA/s1600/Arm+Bones.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="144" data-original-width="482" height="95" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDnJydBaJJkxGj29seU73ZWE7A5kAq6CYtrRQSqi7Ugm_Es82fa34gnnjVt-x1e4_jaUimUSgtWpi90Sjhg3WrQTegzhIWiwdmK4_oJJ1ypwjysNwg_7K_vDHtBNoKna0ivBIom_bENoA/s320/Arm+Bones.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The articulated arm of SNGM-1937</td></tr>
</tbody></table>
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And it turns out that
tightly-folding arms may be the norm, not the exception, among theropods. Avian
arm-folding is, to some degree, present in most, if not all, coelurosaurs. Does
it go farther down the tree than that? <i>Chilesaurus</i>,
here considered a basal tetanurine, could apparently adopt this tight forelimb
posture, and recall that the best specimen of basal, um, saurischian <i>Guaibasaurus </i>is preserved in an “avian resting posture,” complete
with folded limbs (though not to the degree seen in <i>Chilesaurus</i>). Folded limbs are also present in <i>Saltopus</i> and <i>Scleromochlus</i>,
both of which are not even dinosaurs.</div>
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<o:p></o:p></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQTAQDC_rQnM5a7x09sJy88kVwmmPKC3tKQJn7W60NAqxShvovGq81ACpu-1r9475nfOU0R3Aqg_W43Z0pWG3fZacKdXogRzTChsWaWk6ps1xOY8D59OvFQFLM79AQgGGqf7e0Bet74dc/s1600/Chilesaurus+Torso.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="258" data-original-width="482" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQTAQDC_rQnM5a7x09sJy88kVwmmPKC3tKQJn7W60NAqxShvovGq81ACpu-1r9475nfOU0R3Aqg_W43Z0pWG3fZacKdXogRzTChsWaWk6ps1xOY8D59OvFQFLM79AQgGGqf7e0Bet74dc/s320/Chilesaurus+Torso.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">SNGM-1938, with an articulated arm on one side, and a folded-back hand on the other</td></tr>
</tbody></table>
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Now, in birds, the limb-folding
system is essentially automatic—a series of tendons within the propatagium
controls the extension and flexion. If the elbow is extended, the wrist is too
(and vice versa). This is usually seen as a system that evolved in concert with
the feathered wing as a way to protect the primary feathers. However, the fact
that increasingly basal theropods seem to have this same system in place
suggests that (1) the propatagium appeared very early in theropod (or even
dinosauriform) evolution; and (2) its appearance is not connected to flight. I
was shocked to discover that Hutson & Hutson (2014) demonstrated that
automatic wrist-folding guided by soft tissues is also present in <i>modern crocodilians</i>. Automatic
limb-folding, to one degree or another, may be plesiomorphic for <i>Archosauria</i>.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-8kW_sa6VuKhimpeb2egFszmxKDENP8iioKoReQRgQbmy1uqk1_0QhDa1cnKsTxJrvWaYtCHkQ6TqYI_J9_7adkQMvHuOWa3qBOsrw_sk9NnCLlo37rPz4heeA5_sD_gzN1vPwIlbdOc/s1600/Chilesaurus+Drawing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="256" data-original-width="482" height="169" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-8kW_sa6VuKhimpeb2egFszmxKDENP8iioKoReQRgQbmy1uqk1_0QhDa1cnKsTxJrvWaYtCHkQ6TqYI_J9_7adkQMvHuOWa3qBOsrw_sk9NnCLlo37rPz4heeA5_sD_gzN1vPwIlbdOc/s320/Chilesaurus+Drawing.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">*headcannon*</td></tr>
</tbody></table>
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Now, after initially skimming this
paper, I got the mistaken impression that automatic limb-folding supports a
tetanurine identity for <i>Chilesaurus</i>
because the animals around it (<i>Guaibasaurus</i>,
coelurosaurs) also have automatic limb-folding. However, a closer read says
that automatic limb-folding is widely distributed among, well, archosaurs as a
whole, so its presence or absence in a given taxon may not be a valid
phylogenetic signal. Thus, my hope that <i>Chilesaurus</i>
has something to do with the origin of Ornithischia remains intact!</div>
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<o:p></o:p></div>
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It also brings up some interesting
questions. Did ornithischians retain this ability or lose it in the transition
from bipedality to quadrupedality? Certainly, the change in forelimb posture from
medially-facing to rear-facing palms would have had an effect. Did bipedal
ornithischians, like heterodontosaurs, basal ceratopsians, and basal
ornithopods retain automatic wrist-folding? How about basal sauropodomorphs
versus proper sauropods? What’s going on with <i>Aardonyx</i>?<o:p></o:p></div>
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I never gave much thought to
arm-folding in dinosaurs but it turns out it’s super interesting.<o:p></o:p></div>
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Oh, I almost forgot: this paper
also includes a restoration of the folded forelimb of <i>Chilesaurus</i>. The second finger only has one squat little phalanx,
and the third finger is nothing but a greatly-reduced metacarpal and a little
nubbin of a phalanx. So that’s something.<o:p></o:p></div>
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But I’m still waiting for that
full description.<o:p></o:p></div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com2tag:blogger.com,1999:blog-4675540394850433221.post-29643926967879118982017-11-22T13:31:00.002-08:002017-11-22T13:31:53.414-08:00An Aelurodon of My Own<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8vR6OGEoTmtQv3KHJrVmrEkIqBd0Ct_IUEvyLdTB-w23OuaqTvaS6dodUkWHZ_d_Z4jHPxCNRq_SSZPFKDtz_McgRR2wG8rVS7shWtWr3nvmfJ3WpWvgAvsRHYS1fo014vPmHJWSbTCY/s1600/Aelurodon+Anton.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="925" data-original-width="1600" height="185" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8vR6OGEoTmtQv3KHJrVmrEkIqBd0Ct_IUEvyLdTB-w23OuaqTvaS6dodUkWHZ_d_Z4jHPxCNRq_SSZPFKDtz_McgRR2wG8rVS7shWtWr3nvmfJ3WpWvgAvsRHYS1fo014vPmHJWSbTCY/s320/Aelurodon+Anton.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Aelurodon ferox</i> chasing <i>Neohipparion</i>, by Mauricio Anton</td></tr>
</tbody></table>
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You know, I never blogged about my SVP 2017 experience, more out of
sloth than anything else. I can wrap up my thoughts with this sentence: it was fun but very lonely. For me, perhaps the most enjoyable part of the conference was the silent auction. I should have stayed for the following “real” auction
because photos posted to social media afterward made it look insane, but I had
a bunch of meds to do and an early start the next morning. I bid on several
items in the silent auction, most of them 3D prints of interesting fossils, but
I was quickly outbid past my own point of comfort for most of them. However, I
was able to secure this nifty specimen:</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtVxNRLz-FWvPsKMjT8zZE0-cjB627Tsx-5VpHdhP_uaPT3ZKYD_Or9zoXiEC9eqrIjR53MLUHHxXPNrC1WiMtHl51aql0r4hXb5D6KOCLHy9eXI1ZoS23FnvPWTD56GxDHzLdxWhC1zo/s1600/IMG_20171122_120721.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtVxNRLz-FWvPsKMjT8zZE0-cjB627Tsx-5VpHdhP_uaPT3ZKYD_Or9zoXiEC9eqrIjR53MLUHHxXPNrC1WiMtHl51aql0r4hXb5D6KOCLHy9eXI1ZoS23FnvPWTD56GxDHzLdxWhC1zo/s320/IMG_20171122_120721.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lateral view of MOR 1724 (cast).</td></tr>
</tbody></table>
That is a very nice cast of MOR 1724, the holotype of <i>Aelurodon montanensis</i>. I recognized the
name at the time but couldn’t place it—I’d later realize that <i>Aelurodon</i> is a multi-species genus of
borophagine dog. Borophagines are really cool; I learned about them in the
excellent book <u>Dogs: Their Fossil Relatives and Evolutionary History</u> by
Wang & Tedford (2010) with gorgeous illustrations by Mauricio Anton.<br />
<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih7ysnLreuV0AT89uQOSEE6JH5MavRdhNRsJl3R8r2H5n5gnsTgLWA1M7YvUp5l9zY9v7Bq_EN0xVf_iyCfU-IHTBgu4KEWrDQIZCFq9lIcnqvpfC1tLicmQGWYoqxj-SNLq6nBBZbq3s/s1600/IMG_20171122_120733.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih7ysnLreuV0AT89uQOSEE6JH5MavRdhNRsJl3R8r2H5n5gnsTgLWA1M7YvUp5l9zY9v7Bq_EN0xVf_iyCfU-IHTBgu4KEWrDQIZCFq9lIcnqvpfC1tLicmQGWYoqxj-SNLq6nBBZbq3s/s320/IMG_20171122_120733.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Medial view of MOR 1724 (cast)</td></tr>
</tbody></table>
Borophagines were the canid versions of hyenas,* developing
a hypercarnivorous diet and bone-crunching molars, although never to the same
extent as modern hyenas. They never got all that big; <i>Epicyon</i> was five feet long and it is one of the largest canids.
Meanwhile, <i>Borophagus</i>, the mostly
solidly-built borophagine, was only the size of a coyote.<i> </i>However, they were powerfully built, with especially strong necks
and large heads. As the group became better-adapted at bone-crunching, the
heads changed shape: the forehead became more prominent and the snout shortened.
<i>Aelurodon</i> falls somewhere between a
typical canid (like a wolf) and <i>Borophageus</i>,
which had the most bone-crushing adaptations.</div>
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<br />
<br />
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<br />
There are many species of <i>Aelurodon</i>, which appear to have two subgroups within the genus: an <i>A. taxoides</i> species group and an <i>A. saevus</i> species group. I don’t know
enough about this animal to tell you what the difference is, but that’s not why
I’m writing this blog post.<o:p></o:p></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmy2WPF1mWYEFTirp0PJncFPPuItA53TxCrLK6_2m4xL7mAssGBsJu_GMnechJ8JzQUs159Uq1ZNyGqpYb2MkmD-sIr3Jl5GTbODWfAisvXNijdgrxthqO6lefu5mFlD22cS21Fuw1iLY/s1600/Aelurodon+Photo.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1404" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmy2WPF1mWYEFTirp0PJncFPPuItA53TxCrLK6_2m4xL7mAssGBsJu_GMnechJ8JzQUs159Uq1ZNyGqpYb2MkmD-sIr3Jl5GTbODWfAisvXNijdgrxthqO6lefu5mFlD22cS21Fuw1iLY/s320/Aelurodon+Photo.jpg" width="280" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Note there is no medial view of the upper jaw fragment.</td></tr>
</tbody></table>
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This cast has been sitting in my office ever since. Well,
just yesterday, while falling into a Wikipedia hole, I came across <a href="https://web.archive.org/web/20081216211915/http://www.nhm.org/expeditions/rrc/wang/documents/Wangetal2004MontanaAelurodon.pdf">Wang et al.(2004)</a>, which describes my specimen! It is the holotype of a new species, <i>A. montanensis</i>, and is the only
representation of the genus in Montana. However, I was surprised to find that,
while my lower jaw fragment matches the photos in the description, my upper jaw
fragment differs considerably, as if my cast has a lot more bone connecting the
teeth than the specimen as figured in the paper. In particular, there is a
chunk of bone holding the canine in place with a distinct foramina on the
lateral side. On the medial side, there seems to be a more or less continuous
strip of bone going from the canine to the anterior half of P4. Additionally,
my cast features a chunk of small chunk of bone surrounding the root of M1.</div>
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Was more material found than was figured in the description,
perhaps later? It’s a bit of a puzzle, but I am very happy that my cast was
actually described and that it represents a new species of <i>Aelurodon</i>. It’s inspiring me to learn more about borophagine dogs
and in fact, I’ve downloaded this <a href="https://www.researchgate.net/publication/267156822_Phylogenetic_systematics_of_the_Borophaginae_Carnivora_Canidae">massive monograph</a> (Wang, Tedford &
Taylor, 1999) and I intend to at least skim the whole thing.<o:p></o:p></div>
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Quality casts and 3D prints of fossils are so important for
education and outreach. <a href="http://waxing-paleontological.blogspot.com/2015/01/aquilops-in-my-hand.html">I’ve said this before</a>, but I’m stressing it again here.
It’s one thing to read about a specimen and look at pretty photographs of it,
but it’s another thing entirely to actually hold the thing and inspect it
firsthand. Thank you to the Museum of the Rockies (I assume) for donating this
excellent cast to the silent auction!<o:p></o:p></div>
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*But aren't hyenas a kind of dog? Turns out they're not! They're sitting neatly on the feline branch of the Carnivora. I know, I was surprised when I found this out, too.</div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-67983913217944434082017-10-27T15:51:00.000-07:002017-10-31T12:24:35.793-07:00Peg Teeth<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE6bEZ58E4lhHm7YrJAMRaYPQXewB-13CGA78R-VlZGxEHYGOmr69Pm-JVyVdqbpRynjmjy5l5GpYD5cYqWXIqr7L8kycEYvbj4aUMEb6uKhzUcedFHnQ8pDNChtHK4g7yoWtJrKgBGko/s1600/Aquilops+Teeth.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="627" data-original-width="1600" height="125" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE6bEZ58E4lhHm7YrJAMRaYPQXewB-13CGA78R-VlZGxEHYGOmr69Pm-JVyVdqbpRynjmjy5l5GpYD5cYqWXIqr7L8kycEYvbj4aUMEb6uKhzUcedFHnQ8pDNChtHK4g7yoWtJrKgBGko/s320/Aquilops+Teeth.jpg" width="320" /></a></div>
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<span style="font-size: 12pt;">I’m in the
midst of drafting (for the third time) an upcoming post about </span><i style="font-size: 12pt;">Drepanosaurus</i><span style="font-size: 12pt;"> and </span><i style="font-size: 12pt;">Avicranium</i><span style="font-size: 12pt;"> but I doubt they’ll be done by the end of the month.
However, I wanted to get something up on this darn blog because I'd like to
maintain the illusion of being loyal to my seven or eight readers. So I’m going
to briefly discuss something strange about ceratopsians that nobody ever seems to comment on: the weird peg teeth of basal neoceratopsians.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">What teeth
am I talking about? Well here’s a specimen of <i>Yinlong</i> (IVPP V14530) that shows them pretty nicely.<o:p></o:p></span></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE2ttRqVu63N6yU57nTfXaRHuavrXqR9B0DHO-FMscYYBh50J6mnoGd1vKbeYhoZ6LsgJtk5ySkXjHdOAoimSoyvHtPMXKoCqDwRQvz2s-yh2jEhuw7P-6rifZ9eq4CEW4D9SL_nB_Sk0/s1600/Yinlong+Skull.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1133" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE2ttRqVu63N6yU57nTfXaRHuavrXqR9B0DHO-FMscYYBh50J6mnoGd1vKbeYhoZ6LsgJtk5ySkXjHdOAoimSoyvHtPMXKoCqDwRQvz2s-yh2jEhuw7P-6rifZ9eq4CEW4D9SL_nB_Sk0/s320/Yinlong+Skull.jpg" width="226" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Yinlong</i> has some big ones.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">These peg
teeth are widely distributed among basal ceratopsians and are surprisingly
consistent between taxa. There are always at least two, and never more than
four, peg teeth per premaxilla, they differ substantially from the cheek teeth,
and they oppose the predentary bone. In many of these basal taxa, the rostral
bone originates ahead of the tip of the predentary, which makes me wonder
what purpose the rostral is even serving in these basal forms. Even assuming
“cheek-like” structures covering the cheek teeth, the peg teeth would have been
visible in the living animal even if the mouth was closed given that they
oppose the predentary.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span>
<span style="font-size: 12.0pt; line-height: 115%;">The
morphology of these peg teeth is interesting. The crowns are broadest at the
base and narrow towards the tip—a sort of asymmetrical teardrop shape. In many peg-teeth-bearing taxa, the crowns are equipped
with serrations.<o:p></o:p></span></div>
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<span style="font-size: 12pt;">Interestingly,
while peg teeth are present in </span><i style="font-size: 12pt;">Yinlong</i><span style="font-size: 12pt;">
and many other basal ceratopsians, they are absent in </span><i style="font-size: 12pt;">Psittacosaurus</i><span style="font-size: 12pt;"> and </span><i style="font-size: 12pt;">Mosaiceratops</i><span style="font-size: 12pt;">.</span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjXGXJlrZiTYJOtr4iCbRxv9oczeDCPfbwX7XLIH9YXaMvay-qGy43gKEEl1U6Ea0SgBbdKZXw96z1Adn3_nWY0XoiNfKfwm4qbo8ax7a4BZG1BgJoCS30GOPlPx1VtPzrMe2LtbapCrc/s1600/Auroraceratops+Noggin.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="382" data-original-width="1004" height="121" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjXGXJlrZiTYJOtr4iCbRxv9oczeDCPfbwX7XLIH9YXaMvay-qGy43gKEEl1U6Ea0SgBbdKZXw96z1Adn3_nWY0XoiNfKfwm4qbo8ax7a4BZG1BgJoCS30GOPlPx1VtPzrMe2LtbapCrc/s320/Auroraceratops+Noggin.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Auroraceratops</i> has some big premaxillary teeth.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">However,
among non-psittacosaurid basal neoceratopsians, they are present in a number of taxa: </span><i style="font-size: 12pt;">Aquilops</i><span style="font-size: 12pt;"> (that's it at the top of the post)</span><i style="font-size: 12pt;">, Archaeoceratops</i><span style="font-size: 12pt;">, </span><i style="font-size: 12pt;">Auroraceratops</i><span style="font-size: 12pt;">, </span><i style="font-size: 12pt;">Liaoceratops</i><span style="font-size: 12pt;">, </span><i style="font-size: 12pt;">Yamaceratops, </i><span style="font-size: 12pt;">and
</span><i style="font-size: 12pt;">Protoceratops</i><span style="font-size: 12pt;"> </span><i style="font-size: 12pt;">andrewsi</i><span style="font-size: 12pt;"> but not </span><i style="font-size: 12pt;">P.
hellenikorhinus</i><span style="font-size: 12pt;">. There might be others I'm forgetting but those are the papers I have in front of me and I'm trying to bang this post out quickly. Peg teeth are absent in leptoceratopsids (that I know of), </span><i style="font-size: 12pt;">Zuniceratops</i><span style="font-size: 12pt;">, </span><i style="font-size: 12pt;">Turanoceratops</i><span style="font-size: 12pt;">, and Ceratopsidae.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">Among other
ornithischians, the only other group I know of that has dentition that even vaguely resembles those peg teeth are…heterodontosaurs. While best known for
their impressive caniniform teeth, heterodontosaurs also have small
premaxillary teeth that oppose the predentary. They are present in <i>Echinodon</i>, <i>Tianyulong</i>, <i>Abrictosaurus</i>,
<i>Heterodontosaurus</i>, and <i>Lycorhinus</i>. In most of these animals,
the premaxillary teeth are morphologically quite different from those of basal
ceratopsians. </span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyoxPeJO4GZNPG-whKthyphenhyphenFqFRgpkBUC65N9Jm6LMTWurrClqSlp1u5zMQK5klRCi03u7OfVrsZmAl37LgV5_6FR2isVMsa7zqyYkesHpV1vre-g_Uv4ixfQvu6yunF-QxLwlo0wz-T_ow/s1600/Echinodon.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="695" data-original-width="999" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyoxPeJO4GZNPG-whKthyphenhyphenFqFRgpkBUC65N9Jm6LMTWurrClqSlp1u5zMQK5klRCi03u7OfVrsZmAl37LgV5_6FR2isVMsa7zqyYkesHpV1vre-g_Uv4ixfQvu6yunF-QxLwlo0wz-T_ow/s320/Echinodon.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Sereno's reconstruction of <i>Echinodon</i>'s teeth.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">Rather than having a teardrop shape, their teeth are more or less
straight and taper to the tip. In </span><i style="font-size: 12pt;">Heterodontosaurus</i><span style="font-size: 12pt;">
and </span><i style="font-size: 12pt;">Lycorhinus</i><span style="font-size: 12pt;">, the premaxillary teeth
become progressively larger posteriorly. The largest of these (pm3) is a proper
fang, slightly recurved, that would have overlapped the lateral edges of the
predentary. In </span><i style="font-size: 12pt;">Heterodontosaurus</i><span style="font-size: 12pt;">,
who’s been rigorously monographed by Norman et al. (2011), the two anterior
premaxillary teeth are not serrated but the largest “caniniform” tooth bears
“small square-edged serrations” on its distal edge.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">In <i>Echinodon</i>, however, Sereno (2012) writes
that:<o:p></o:p></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">There are three premaxillary teeth in middle and posterior
portions of the premaxilla, preceded by an edentulous margin…the crowns are slightly swollen, the mesial side
of the crown base more bulbous than the distal side, and have smooth surfaces
without denticles or serrations. The crowns are gently recurved with apices set
slightly distal to the center of the crown base.<o:p></o:p></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">Indeed, in
his reconstruction of <i>Echinodon</i>, above, there are superficial similarities to the premaxillary teeth of basal ceratopsians.<o:p></o:p></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">I don’t
think this similarity is necessarily evidence of a close relationship between
heterodontosaurs and ceratopsians (although that idea has been floated before).
However, functionally speaking, there may be some overlap here.<o:p></o:p></span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTn66MlXFzEwpKMrhlfqagTveH_UEti9Jp7fzEnS_Xb61eEhuzAeoVx2rrMMtyETDfL1Fp9FbzAinlX7PkKDRUUIvPooJFSo-UovQq5VMddqpT0yOtdJEpF_dkXH_Ys5DcOV7Bp9ovPZM/s1600/Heterodontosaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="792" data-original-width="1008" height="251" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTn66MlXFzEwpKMrhlfqagTveH_UEti9Jp7fzEnS_Xb61eEhuzAeoVx2rrMMtyETDfL1Fp9FbzAinlX7PkKDRUUIvPooJFSo-UovQq5VMddqpT0yOtdJEpF_dkXH_Ys5DcOV7Bp9ovPZM/s320/Heterodontosaurus.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Heterodontosaurus</i>' teeth are quite different from <i>Echinodon</i>.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">Sereno
writes that the premaxillary teeth of heterodontosaurs do actually show wear on
their lingual side from tooth-to-bill contact. As for the large caniniform
teeth of </span><i style="font-size: 12pt;">Heterodontosaurus</i><span style="font-size: 12pt;"> and </span><i style="font-size: 12pt;">Lycorhinus</i><span style="font-size: 12pt;">, Sereno assigns their
function to puncturing, cropping and rooting: </span><br />
<span style="font-size: 12pt;"><br /></span>
<span style="font-size: 12pt;">“Crown breakage in the
premaxillary series suggests at least occasional contact with hard materials,
as may occur in the course of agnostic or rooting behaviors.”</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">Could their
premaxillary teeth be used to acquire squirmier food?
Barrett (2000) suggested that heterodontosaurs may have been facultative
omnivores. This position was supported by Butler et al. (2008), who noted that the
caniniforms develop early in ontogeny and so were not strictly for display.
Porro (2011) also suggested frequent omnivory. </span><span style="font-size: 12pt;">Norman et al. (2011), in their </span><i style="font-size: 12pt;">Heterodontosaurus</i><span style="font-size: 12pt;"> monograph,
considered both it's caniniform teeth and grasping, raptorial forearms as
evidence for catching and consuming small prey items, raiding nests and/or opportunistic scavenging.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_aIhRVyNsy7NAWacjC32_p1d3MpooOqzomE9DmIlQISoUEHuvBzDzf1zGloCc8KhAryqeuQNzNm_XkJT-FTuAwg3GRsgFkH9r3UtkHh-NaWHYea9I0zaLUiEYujr8a5Ll6LR5HnF1cJA/s1600/Peccary.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="731" data-original-width="800" height="292" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_aIhRVyNsy7NAWacjC32_p1d3MpooOqzomE9DmIlQISoUEHuvBzDzf1zGloCc8KhAryqeuQNzNm_XkJT-FTuAwg3GRsgFkH9r3UtkHh-NaWHYea9I0zaLUiEYujr8a5Ll6LR5HnF1cJA/s320/Peccary.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Peccary from Wikipedia, by Tim Vickers.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">However,
Thulborn (1974) and Norman et al. (2011) also compare heterodontosaurs to
peccaries, which are modern herbivores with canines. Peccaries use their
canines to settle arguments and as defense against predators “…and may
represent the closest living analogs to heterodontosaurids.” Sereno finds that
heterodontosaurs were mostly likely predominantly, if not exclusively,
herbivorous.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">The analogy
with heterodontosaurs may be helpful in figuring out the function of the
premaxillary teeth of basal ceratopsians. They share many similarities:<o:p></o:p></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5ORkrEOcIxzNMzmaJP1PZxDMCwgZyQLVgbAlg9zQ1SKi0aTgoNwa7eCKQbtiJ4jnVf_k0QEkNRHGLDS1EuX_rWLt6EFlVHmIgASg_OEyc3J7MytLhNA00i6h6ZRFkUna3V1Gek7Xc4p4/s1600/Liaoceratops+Juvenile.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="602" data-original-width="375" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5ORkrEOcIxzNMzmaJP1PZxDMCwgZyQLVgbAlg9zQ1SKi0aTgoNwa7eCKQbtiJ4jnVf_k0QEkNRHGLDS1EuX_rWLt6EFlVHmIgASg_OEyc3J7MytLhNA00i6h6ZRFkUna3V1Gek7Xc4p4/s320/Liaoceratops+Juvenile.jpg" width="199" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This juvenile <i>Liaoceratops</i> has 'em.</td></tr>
</tbody></table>
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<span style="font-size: 12pt;">1. Size and
number of premaxillary teeth is variable between taxa;</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">
2. Premaxillary teeth turn up early in ontogeny (Hone et al. 2014, Xu et al.
2002);<br /><br />
</span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">3. Premaxillary teeth oppose the predentary.<o:p></o:p></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">From these
three similarities, we can make three inferences:<o:p></o:p></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">1. Unlike
the cheek teeth of ceratopsians or the carnivorous dentition of theropods, the
variation seen in basal ceratopsian premaxillary teeth implies they were not
consistently used for any single purpose, like gathering or processing food, because in that case their morphology would be more uniform.<br /><br />
</span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">2. Their appearance early in ontogeny, coupled with difficulties in
demonstrating sexual dimorphism in ceratopsians, shows that the premaxillary
teeth were not primarily for display.<br /><br />
</span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">3. The premaxillary teeth must have been at least somewhat important for cropping
vegetation until the embiggening of the rostral overtook their role.<o:p></o:p></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">
</span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">But, like
peccaries and heterodontosaurs, I think it's likely that basal ceratopsians used their peg teeth
to settle arguments and nip attackers. Note that, in <i>Protoceratops</i>, the rostral is enormous and the premaxillary teeth
have been reduced to toothpicks—a far cry from the proportionately larger teeth
of <i>Aquilops, Liaoceratops</i> and <i>Auroraceratops</i>. Given their apparent
loss in <i>P. hellenikorhinus</i> (Lambert
et al. 2001), I wonder if their presence is variable in <i>P. andrewsi</i>. Maybe at a certain point their presence became as
variable as our wisdom teeth. But certainly, in <i>Protoceratops</i>, the rostral was doing their job just fine.<o:p></o:p></span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<div class="MsoNormal">
<span style="font-size: 12pt;">But wait, you say, what about those other marginocephalians, the pachycephalosaurs? What do they have in the premaxillary dentition department? Unfortunately, pachycephalosaurs are not famous for their beautifully complete skulls or skeletons, but </span><i style="font-size: 12pt;">Stegoceras validum</i><span style="font-size: 12pt;"> does have three small premaxillary teeth (per side) that oppose the predentary. The crowns are roughly teardrop-shaped have large denticles. Like heterodontosaurs, the wear patterns are suggestive of tooth-to-bill motion. </span><i style="font-size: 12pt;">Prenocephale</i><span style="font-size: 12pt;"> apparently has similar wear facets on its premaxillary teeth. It would be interesting to find out how variable premaxillary tooth count and morphology are in pachycephalosaurs, but that part of the skull is so rarely preserved. For what it's worth, <i>Dracorex</i> (and I assume <i>Pachycephalosaurus</i>) does not have any premaxillary teeth.</span></div>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEKAnEZd2bg_yqUArSnEuK3OQeSFXEW3kmGDDvQv_n3_KTGfbydeOymcgyDyBqTJks3gz9ovWAxHCYedZC1BHsPjdCWuWlijXG58rdPbaYUAEYohDTXuWDcVcw9MfcY7Y6Zz61YIOBUhg/s1600/Stegoceras.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="335" data-original-width="1070" height="125" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEKAnEZd2bg_yqUArSnEuK3OQeSFXEW3kmGDDvQv_n3_KTGfbydeOymcgyDyBqTJks3gz9ovWAxHCYedZC1BHsPjdCWuWlijXG58rdPbaYUAEYohDTXuWDcVcw9MfcY7Y6Zz61YIOBUhg/s400/Stegoceras.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Stegoceras</i> skull: diagram at left and closeup of the premaxillary teeth on the right.</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="font-size: 12.0pt; line-height: 115%;">It seems that six premaxillary teeth is the plesiomorphic condition for ornithischians, as seen in <i>Lesothosaurus</i>, <i>Scuttelosaurus, Isberrysaura</i>, and even <i>Thescelosaurus. </i>If heterodontosaurs are the basalmost ornithischians, then they reduced their premaxillary tooth count independently of marginocephalians, but it is interesting to note that basal ornithopod <i>Haya</i> has five rather pointy, unserrated premaxillary teeth and <i>Jeholosaurus</i> has six. </span><br />
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO6C6F8PxqutRRNMvtzIYO278rkKLgd7CKJKelX-PMtwiobR8fx3-ryu_70hvDu25fU6oloGZz0rKzKty399Z4htX4e3kTHL_zm_M2pt9MkQfGAUkCs_K5j1Lf5Z_dD-odNRGNNL8NZ6M/s1600/Haya.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="328" data-original-width="694" height="151" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO6C6F8PxqutRRNMvtzIYO278rkKLgd7CKJKelX-PMtwiobR8fx3-ryu_70hvDu25fU6oloGZz0rKzKty399Z4htX4e3kTHL_zm_M2pt9MkQfGAUkCs_K5j1Lf5Z_dD-odNRGNNL8NZ6M/s320/Haya.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The nicely-preserved skull of <i>Haya</i>. Note the elongated premaxillary teeth.</td></tr>
</tbody></table>
<span style="font-size: 12pt;">Given that marginocephalians and ornithopods are usually found to be sister groups, it's interesting that basal members of both groups are quite different regarding their premaxillary teeth, both in number and morphology.</span></div>
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<span style="font-size: 12.0pt; line-height: 115%;">(not that I'm doubting the validity of a monophyletic Cerapoda, mind you.)</span><br />
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span>
<span style="font-size: 12.0pt; line-height: 115%;">So there you have it. Basal ceratopsians have weird peg teeth in the premaxillae, their function might be similar to that of heterodontosaurs, and they differ both from their closest relatives (pachycephalosaurs) and from basal members of their sister group (Ornithopoda).</span><br />
<span style="font-size: 12.0pt; line-height: 115%;"><br /></span>
<span style="font-size: 12.0pt; line-height: 115%;">Oh, and Happy Halloween! Don't let the vampiritic anurognathids bite!</span></div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-40874489126592800632017-09-25T15:35:00.001-07:002020-02-07T11:02:34.114-08:00Very Specific Strange Reptiles<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoxigfZRTK_FMiOu3i5FGfqmI0w_tovasntTgRKRBwV4uYMBocFy8v89u9zklJi5VYZLW-j0MoDD5sAZ3QoovRi6tbIY3J1NsF7K3Gwa0DDSPYGtjZqvoEyC09nL1wBQMjufqI9691bec/s1600/2014_Azendohsaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="921" data-original-width="1600" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhoxigfZRTK_FMiOu3i5FGfqmI0w_tovasntTgRKRBwV4uYMBocFy8v89u9zklJi5VYZLW-j0MoDD5sAZ3QoovRi6tbIY3J1NsF7K3Gwa0DDSPYGtjZqvoEyC09nL1wBQMjufqI9691bec/s400/2014_Azendohsaurus.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Azendohsaurus madagaskarensis</i> by Matt Celeskey.</td></tr>
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The term "strange reptiles" could apply to just about every animal I've ever written about on this blog, so you'll forgive me for not loving the name Allokotosauria, an up-and-coming group that was formalized in 2015. The name really says nothing about its members, the similarly newly-minted Azendohsauridae
and the longstanding Trilophosauridae. These are archosauromorphs that sit well
outside of the Ornithodira-Crurotarsi divide, and are instead related to such
eclectic animals as rhynchosaurs and protorosaurs. As I suspect my readers have at least heard of <i>Trilophosaurus</i>, I'll start this essay by discussing <i>Azendohsaurus</i>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiahthBAXNoMHLkUkTyVNNyf4dT93tpSf9QA-1KbETAetAvbHrP4to88Ryd32U7EhjkXTA2gcKMeTNixcu2rMzp3Wr_NICbPukccyEK5eFXVws8YGCww-c25kUIRmRLKCcXRFQ1wMC9iaY/s1600/A.+laarousii.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="499" data-original-width="377" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiahthBAXNoMHLkUkTyVNNyf4dT93tpSf9QA-1KbETAetAvbHrP4to88Ryd32U7EhjkXTA2gcKMeTNixcu2rMzp3Wr_NICbPukccyEK5eFXVws8YGCww-c25kUIRmRLKCcXRFQ1wMC9iaY/s320/A.+laarousii.png" width="241" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Azendohsaurus laaroussii</i></td></tr>
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<i>Azendohsaurus
laaroussii</i> was initially described in 1972 by Dutuit as a Moroccan
ornithischian dinosaur—it had those leaf-shaped teeth, after all, but it was
quickly moved into the “Prosauropoda” by subsequent studies. There's not much to the holotype--a fragment of dentary and a partial maxilla, both with teeth--but that was enough (in 1972) to warrant a dinosaurian identity. Several decades later, disarticulated
postcranial remains discovered at the holotype site suggested that either <i>Azendohsaurus</i>
was not a dinosaur at all or that taphonomic processes had mixed the holotype
skull—still possibly a dinosaur—and the postcranial remains, which were
definitely NOT from a dinosaur. Unambiguously associated cranial and
postcranial material would be necessary to determine the true identity of <i>Azendohsaurus</i>.</div>
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Well, don’tcha know those associated remains were found in
the 1990's in Madagascar of all places, during a field survey. <a href="https://www.academia.edu/13535963/A_new_species_of_Azendohsaurus_Diapsida_Archosauromorpha_from_the_Triassic_Isalo_Group_of_southwestern_Madagascar_cranium_and_mandible?auto=download">John Flynn and colleagues</a> (2010) discovered a monotypic bonebed of an animal that matched up
quite well with the Moroccan holotype skull. The authors named and described their
new animal as <i>Azendohsaurus
madagaskarensis</i> and determined that it was not a dinosaur—far from it, in
fact. Among its obviously non-dinosaurian features include nasal bones that do not
contact the premaxillae, making for an undivided naris; an incomplete lower
temporal bar; and a multitude of teeth on the vomers, palatines, and
pterygoids (and that's just the skull). The authors eventually found it to be outside of Archosauriformes
while noting its many features convergent with prosauropods. While a
description of the postcranial material was outside the scope of Flynn et al.
(2010), that paper did come a few years later.<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrw02Jqf4Gtog7HC9FxgcdapWY-ulE14H5OEKMANwwfFq0xznCuGh0CcGq835OfpTPJKd9de6Qz5mYFzo1Jf6JQ2rkLHyQaycrxY5YxTWey0UaI2sLa5Npya-vkO8uGBvBYOUQ3ptp4ps/s1600/A.+madagaskarensis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="477" data-original-width="375" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrw02Jqf4Gtog7HC9FxgcdapWY-ulE14H5OEKMANwwfFq0xznCuGh0CcGq835OfpTPJKd9de6Qz5mYFzo1Jf6JQ2rkLHyQaycrxY5YxTWey0UaI2sLa5Npya-vkO8uGBvBYOUQ3ptp4ps/s320/A.+madagaskarensis.jpg" width="251" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The skull of <i>Adendohsaurus madagaskarensis</i></td></tr>
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<a href="http://digitallibrary.amnh.org/handle/2246/6624">Nesbitt et al.</a> (2015) describes the completely-known
skeleton of <i>Azendohsaurus madagaskarensis</i>
in an impressive monograph for the Bulletin of the American Museum of Natural
History. It paints a picture of a large-bodied quadruped with a long neck and surprisingly robust pectoral girdle. The animal’s fingers are all of similar size
and shape as opposed to, say, <i>Trilophosaurus</i>
with its fingers of increasing length toward the outer edge of the hand (except
the short pinkie). The feet are of similar construction, with large claws on
each toe. A phylogenetic analysis placed <i>Azendohsaurus</i>
as a sister taxon to a group containing <i>Trilophosaurus</i>,
<i>Spinosuchus</i>, and <i>Teratepeton</i> (but read on). India’s suddenly-not-that-weird <i><a href="http://www.sciencedirect.com/science/article/pii/S1367912002001104">Pamelaria</a></i>, described in 2003 as a new kind of protorosaur, turns out to be an outgroup to this
dichotomy.</div>
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It is this large clade—<i>Pamelaria</i>
plus those other guys—that constitutes the Allokotosauria ("strange reptiles"). Azendohsauridae only included one genus (<i>Azendohsaurus</i>) and two species (<i>laaroussii</i> & <i>madagaskarensis</i>) until just recently. </div>
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While I was waiting in the Seattle airport to board my
plane to Calgary for SVP this year, a new azendohsaurid was described—<i><a href="https://www.nature.com/articles/s41598-017-08658-8">Shringasaurus indicus</a></i>. Another Indian
form, <i>Shringasaurus</i> is known from another
large monotypic bonebed featuring animals of many different ages. In general,
it looks similar to <i>Azendohsaurus</i>
with one big caveat: each of its frontal bones bears a robust, forward-curving
horn that Sengupta et al. (2017) compares to ceratopsids. You can actually line
up frontals from young to old animals and watch the horns grow. Surprisingly,
one pair of frontals in the bonebed, while the same size and shape of the
horned frontals, completely lacks horns. The authors cite this as evidence of
sexual dimorphism. I’m not sure you can make that argument with one data point,
but it’s an interesting idea. The authors’ phylogenetic analysis placed <i>Shringasaurus</i> as a sister taxon to <i>Azendohsaurus</i> and <i>Pamelaria</i> moves from being the most basal allokotosaurian to the
most basal azendohsaurid (not a big leap).<o:p></o:p></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeCQ852hFZsY_sDGQKvzImhhbVzMhVvek69jMXIHdUk3uFA4GqLRx4Rpdv1yuXMXSFsL4hsmqU62DejaavLxcRE43RLQ0G78vgnH-ouzJCYbzH5XluhN58YSznd1sD1GSuQPbgo27A5fs/s1600/Azendohsaurus+Postcrania.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="446" data-original-width="1600" height="110" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeCQ852hFZsY_sDGQKvzImhhbVzMhVvek69jMXIHdUk3uFA4GqLRx4Rpdv1yuXMXSFsL4hsmqU62DejaavLxcRE43RLQ0G78vgnH-ouzJCYbzH5XluhN58YSznd1sD1GSuQPbgo27A5fs/s400/Azendohsaurus+Postcrania.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A full skeletal reconstruction of <i>Azendohsaurus madagaskarensis</i>.</td></tr>
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Generally speaking, azendohsaurids were large-bodied
quadrupeds with long necks and small heads equipped with spatulate teeth. They
look like the group of animals that sauropodomorphs evolved from in some
alternate universe. They were around during the Middle-Late Triassic, so they
may have lived alongside their dinosaurian counterparts for a little while.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmg9oL2O7j9a6p1Gwu6cpCQBdj0HfbR8pogG5wkIZEfSKIWWzlPJ48kPzgaQbXCJOtQjBrnpN0LTUMaHjws4_6VMlHQgHUxxEdmi2E-UnqDQN9MBc_fISheDBFMn-eD5OcP8kmRsn2yJA/s1600/Shringasaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="822" data-original-width="1600" height="205" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmg9oL2O7j9a6p1Gwu6cpCQBdj0HfbR8pogG5wkIZEfSKIWWzlPJ48kPzgaQbXCJOtQjBrnpN0LTUMaHjws4_6VMlHQgHUxxEdmi2E-UnqDQN9MBc_fISheDBFMn-eD5OcP8kmRsn2yJA/s400/Shringasaurus.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The reconstructed skeletal and selected elements of <i>Shringasaurus indicus</i>.</td></tr>
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Geographically speaking, azendohsaurids were, before this
year, limited to Gondwannaland: Madagascar, India, and Morocco. Madagascar and
India were still joined together during the Triassic, but Morocco was a fair
distance away. Sterling Nesbitt gave a talk at SVP this year about <i><a href="https://www.researchgate.net/publication/247604868_Malerisaurus_A_New_Eosuchian_Reptile_from_the_Late_Triassic_of_India">Malerisaurus</a></i>, an old taxon that was originally classified as an "Eosuchian" (and later as a <a href="https://www.researchgate.net/publication/267398643_REINTERPRETATION_OF_THE_HOLOTYPE_OF_MALERISAURUS_LANGSTONI_A_DIAPSID_REPTILE_FROM_THE_UPPER_TRIASSIC_CHINLE_GROUP_OF_WEST_TEXAS">chimaera</a>) that his team
recognized as a basal azendohsaurid that’s from the southwestern United States.
It was a great talk; there’s a lot of material assigned to <i>Malerisaurus</i> and it apparently survived for a very long time. I got
the feeling it was the <i><a href="http://waxing-paleontological.blogspot.com/2016/11/from-triassic-monster-manual.html">Vancleavea</a></i> of
allokotosaurs. I eagerly await the paper.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKFv-E6wwTyGC8gnp5QJUrMZOMeeniaMYalQ38gSEf1UJZ2DCK_xuVGD_Eb53O0Rks0OxcoF6HNC5j41l_SYXLEgUvDNALQ2ZCsN30Hmgctmy3JPDUvB0rAy79aWoOdQGaZnjIlAN3N0c/s1600/Trilophosaurus+Skeletal.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="434" data-original-width="1600" height="105" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKFv-E6wwTyGC8gnp5QJUrMZOMeeniaMYalQ38gSEf1UJZ2DCK_xuVGD_Eb53O0Rks0OxcoF6HNC5j41l_SYXLEgUvDNALQ2ZCsN30Hmgctmy3JPDUvB0rAy79aWoOdQGaZnjIlAN3N0c/s400/Trilophosaurus+Skeletal.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Skeletal reconstruction of <i>Trilophosaurus buettneri</i></td></tr>
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And then there’s the Trilophosauridae. Like the
Azendohsauridae, it's generally thought to include only one genus split into two species: <i>Trilophosaurus buettneri</i> and <i>T. jacobsi </i>(but read on). Surprisingly,
despite being known since 1928, <i>Trilophosaurus</i>
wasn’t fully described until 1945, by Gregory. In 2008, <a href="http://econtent.unm.edu/cdm/ref/collection/bulletins/id/585">Spielmann et al.</a> penned an extensive
monograph for the New Mexico Museum of Natural History and Science Bulletin. They
have lots of material to work with—<i>Trilophosaurus</i>
is apparently quite common. Two other animals have been flip-flopping around
the Trilophosauridae for awhile now—<i>Teraterpeton
hrynewichorum</i> and <i>Spinosuchus
caseanus</i>. Nesbitt et al. (2015) make the case that <i>Trilophosaurus jacobsi</i> is a junior synonym of <i>Spinosuchus caseanus</i>. While <i>Teraterpeton</i> is fragmentary and its assignment to Trilophosauridae tenuous, <i>Spinosuchus </i>is more likely to be a trilophosaurid
(<a href="https://www.academia.edu/457255/Redescription_of_Spinosuchus_caseanus_Archosauromorpha_Trilophosauridae_from_the_Upper_Triassic_of_North_America">Spielmann et al. 2009</a>).</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHzxyTOp3QyvrpGJGzmDie5xzEzTXuCaD-kfiOBK3nZe7KsE3p0aNMoMQ84Uixh2j4tKciFV07h0f7FhV6M9x6lp3SFgI6CBwjXWvNwwFHDQ_g6w-_7EXOdMECXLIK01ggBcnJi7HZ-mU/s1600/Trilophosaurus+in+Life.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="593" data-original-width="522" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHzxyTOp3QyvrpGJGzmDie5xzEzTXuCaD-kfiOBK3nZe7KsE3p0aNMoMQ84Uixh2j4tKciFV07h0f7FhV6M9x6lp3SFgI6CBwjXWvNwwFHDQ_g6w-_7EXOdMECXLIK01ggBcnJi7HZ-mU/s320/Trilophosaurus+in+Life.jpg" width="281" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Trilophosaurus</i> in the treetops by Matt Celeskey</td></tr>
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<i>Trilophosaurus</i> itself
was an iguana-sized animal that would have looked a lot like an iguana in life
and probably spent a lot of time in trees…like an iguana. Its namesake comes
from the distinctive teeth that fill its mouth. The teeth are narrow
front-to-back but quite wide and only appear in the maxillae (and dentary).
Along the width of each tooth are three “peaks” and two “valleys,” giving
the animal its name (“three-crested lizard”). Allokotosaurs (azendohsaurids + trilophosaurids) share
several features in the forearm and skull, but there was some question (in
Nesbitt et al. 2015) about whether <i>Pamelaria</i>
is an outgroup to this pairing or not: </div>
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“Although <i>Pamelaria
dolichotrachela</i> is identified as the nearest outgroup of Trilophosauridae + Azendohsauridae,
curiously a number of derived character states occur in Azendohsauridae and <i>Pamelaria dolichotrachela</i> to the
exclusion of trilophosaurids, apparently homoplastically.”<o:p></o:p></div>
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This ambiguity is seemingly resolved by Sengupta et al.
(2017) who find <i>Pamelaria</i> to be the
basalmost azendohsaurid, rather than the basalmost allokotosaur.<o:p></o:p></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj71_cO7Wm6GNNbDJVAgNnaYai7egeGqlcb1SgLmV6tj_KBc0wLvXipzxArW9piDAxc9knNN3UsWIBaP2XXsDOC_iy_2Akyfk0XObiAk2DHlH1x0iJ5D7XdaWTHd-WORS_8GWDlEwSDNuE/s1600/Pamelaria.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="321" data-original-width="877" height="146" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj71_cO7Wm6GNNbDJVAgNnaYai7egeGqlcb1SgLmV6tj_KBc0wLvXipzxArW9piDAxc9knNN3UsWIBaP2XXsDOC_iy_2Akyfk0XObiAk2DHlH1x0iJ5D7XdaWTHd-WORS_8GWDlEwSDNuE/s400/Pamelaria.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Pamelaria</i>: weird in 2003, not as weird in 2015.</td></tr>
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Azendohsaurs are especially fascinating to me, evolving in the sauropodomorph direction long before sauropodomorphs existed. They were probably the largest herbivores in their ecosystems and could go after food too high for their neighbors. Trilophosaurs are also strange in that they were strongly arboreal--I can't think of any other Middle to Late Triassic reptiles (besides basal pterosaurs) that were spending a lot of time in the trees apart from drepanosaurs--and even they're not a sure thing. Both groups disappeared certainly prior to the Early Jurassic. I imagine azendohsaurs were outcompeted by their dinosaur mimics, the sauropodomorphs, and trilophosaurs may have simply been an unlucky casualty of the Triassic-Jurassic extinction event that cleared the way for dinosaurs to take over.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibro8QXH7JApxV-WhmUh92IR0u0wNSEDEosHmABVaqbGeugfFBk4ugIZpDtJ2exg8N9vM4x2z044Ens86XxwWR7OiMEOvQPxI54OSiAYwUdUOZuGVASXcchdszOTh3p5AdX_Tl_v9rd6g/s1600/Shringasaurus+Life.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1044" data-original-width="1600" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibro8QXH7JApxV-WhmUh92IR0u0wNSEDEosHmABVaqbGeugfFBk4ugIZpDtJ2exg8N9vM4x2z044Ens86XxwWR7OiMEOvQPxI54OSiAYwUdUOZuGVASXcchdszOTh3p5AdX_Tl_v9rd6g/s400/Shringasaurus+Life.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Shringasaurus indicus</i> by Gabriel Ugueto</td></tr>
</tbody></table>
</div>
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Special thanks to Matt Celeskey and Gabriel Ugueto for letting me use their wonderful pieces for this essay!</div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3tag:blogger.com,1999:blog-4675540394850433221.post-16106243183761651632017-08-14T09:57:00.001-07:002017-08-28T15:39:55.604-07:00And Then There Were None<div class="MsoNormal">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcB9gZ5xN8vSbPHFb3kgnWHwhaTtt0dSxxy34TxKeBg7kli3A26kaLI97e2ISlRcWzZINzc9adaRqF0t2k92fhuKIbKFnQC_zzXnwWYlHsWlXtg9ea1kOGZPxlxUmU3aw5l865x7m-rxg/s1600/Pisanosaurus.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="563" data-original-width="750" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcB9gZ5xN8vSbPHFb3kgnWHwhaTtt0dSxxy34TxKeBg7kli3A26kaLI97e2ISlRcWzZINzc9adaRqF0t2k92fhuKIbKFnQC_zzXnwWYlHsWlXtg9ea1kOGZPxlxUmU3aw5l865x7m-rxg/s320/Pisanosaurus.jpg" width="320" /></a></div>
Today, we add an addendum to what’s turned out to be one of
my favorite blog posts: <a href="http://waxing-paleontological.blogspot.com/2016/12/hopeful-dinosaurs.html">Hopeful Dinosaurs</a>. In that essay, I introduced you all
to a group of near-dinosaur dinosauriforms called silesaurids. These small,
quadrupedal, herbivorous critters all hail from the Late Triassic, but were
impressively cosmopolitan, being found in the United States, South America,
Africa, and Poland.<br />
<br />
<a name='more'></a><br />
Among their more interesting features is a
pseudo-predentary that was initially thought to be a precursor to the
ornithischian unifier. However, this pseudo-predentary is not a separate
ossification, but merely a pointed, toothless anterior end of the normal
dentary bones. While silesaurids are usually found to be just outside of the
Dinosauria, a few authors (Dzik, 2003; Ferigolo & Langer, 2007; Langer
& Ferigolo, 2013) have suggested that silesaurids, either as a monophyletic
or paraphyletic group, were basal ornithischians (actual phylogenetic support
for this idea, per Langer & Ferigolo, 2013, remains low).<br />
<br />
<o:p></o:p></div>
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Toward the end of that post, I briefly went over a
conference abstract by Federico L. Agnolin in which he suggested that
foundational Triassic ornithischian <i>Pisanosaurus
mertii</i> was actually a silesaurid. This is surprising given that taxon’s
status as the Last Surviving Triassic Ornithischian.<o:p></o:p><br />
<br /></div>
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Oh, maybe a little background: Prior to 2005,
Triassic ornithischians were downright common, but fragmentary and based on
teeth. Ornithischians, indeed, have unique dentition. But in 2005, Parker et
al. went and harshed that mellow by demonstrating that Late Triassic archosaur <i><a href="http://rspb.royalsocietypublishing.org/content/272/1566/963.full">Revueltosaurus callenderi</a></i> was a pseudosuchian, not an ornithischian as had been previously believed, and had independently evolved ornithischian-like dentition. Furthermore, <i><a href="http://www.ing.pan.pl/Keuper/02_Keuper-literature/Dzik%202003JVP.pdf">Silesaurus</a></i> was described
in 2003 and combined a dinosauriform skeleton with ornithischian-like
dentition: two knocks against Triassic ornithischians that were based on teeth
alone. Parker et al. (2005) sank several ornithischian taxa: <i>Galtonia</i>, <i>Tecovasaurus</i>, <i>Lucianosaurus</i>,
<i>Pekinosaurus</i>, and <i>Technosaurus </i>were no longer unambiguously referable to Ornithischia. They write that “naming
isolated herbivore-like teeth can be hazardous because future work may show
that separate species possess identical dental morphologies.”<o:p></o:p><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHpGrh3D9MU_Zc-uxGloosdOdZrRO3cHZcLTRni8GDWP9NLUWOWYu3s89rzzB1RXx15zbO8G_dD2uTeE4loq2ZjE3iLi9Dy1W6VWiVPY9ngAf1CAIKewTLqc1XYFBuiX8rDddfQUMz2Pg/s1600/Revueltosaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="315" data-original-width="760" height="132" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHpGrh3D9MU_Zc-uxGloosdOdZrRO3cHZcLTRni8GDWP9NLUWOWYu3s89rzzB1RXx15zbO8G_dD2uTeE4loq2ZjE3iLi9Dy1W6VWiVPY9ngAf1CAIKewTLqc1XYFBuiX8rDddfQUMz2Pg/s320/Revueltosaurus.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Gorgeous <i>Revueltosaurus </i>skeletal by Jeff Martz. Obviously not a dinosaur.</td></tr>
</tbody></table>
After this Great Purge, the authors state that only <i>Pisanosaurus</i> (Casamiquela, 1967) and an
unnamed <a href="https://www.researchgate.net/publication/299006661_A_heterodontosaur_ornithischian_dinosaur_from_the_Upper_Triassic_of_Patagonia">Argentinian heterodontosaurid</a> (Baez & Marsicano, 2001) remain as unquestionable Triassic ornithischians. Sadly, since the
heterodontosaurid’s description, Irmis et al. (2007) wrote that its poor
preservation requires further evidence to confirm a heterodontosaurid identity,
Sereno (2012) wasn’t sure it could be diagnosed to Heterodontosauridae at all, and
<a href="https://www.researchgate.net/publication/259408663_Implications_of_the_Newark_Supergroup-based_astrochronology_and_geomagnetic_polarity_time_scale_Newark-APTS_for_the_tempo_and_mode_of_the_early_diversification_of_the_Dinosauria">Olsen, Kent & Whiteside</a> (2011) claimed that the age of the Laguna Colorada
Formation, where it found, could be Late Triassic or Early Jurassic. Thus, a great deal of
ambiguity surrounds this “Triassic heterodontosaurid.”</div>
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<br />
<o:p></o:p></div>
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Since Parks et al. (2005) sank most Triassic ornithischians,
only one other has been discovered: <i><a href="https://www.academia.edu/239852/The_anatomy_of_the_basal_ornithischian_dinosaur_Eocursor_parvus_from_the_lower_Elliot_Formation_Late_Triassic_of_South_Africa">Eocursor parvus</a></i> was described in 2007 and 2010. This South African ornithischian is
wonderfully complete and well-preserved. However, Olsen, Kent & Whiteside
(2011) wrote that the Lower Elliot Formation might also be Early Jurassic
(this was reaffirmed at an SVP talk last year, apparently). Thus, <i>Pisanosaurus</i> is the only “surviving”
unambiguous ornithischian dinosaur. Right?<o:p></o:p></div>
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<br />
Well, maybe not.<o:p></o:p><br />
<br /></div>
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As <a href="http://www.tandfonline.com/doi/abs/10.1080/14772019.2017.1352623?journalCode=tjsp20">Angnolin & Rozadilla</a> (2017) demonstrate, there’s not much keeping <i>Pisanosaurus</i> in
the ornithischian camp. On the contrary, it shares a lot of features with
silesaurids including (but not limited to) details of tooth, sacral vertebrae,
pelvis, tibia, and foot morphology. To make a long story short, they write that: “<i>Pisanosaurus</i>
lacks any features that unambiguously position it among ornithischians and even
dinosaurs, while possessing several traits that are shared with basal
dinosauriforms of the clade Silesauridae.”<br />
<o:p></o:p><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiEDw_M9ZNg76qWuSeUuNHOR1ceKWZ9eqHTokVx9HF2ZhNdZXivhK9K2C_vmmQRgBQqLnUemEgdpUo9Nn1ysgpcX56xEcAuTCGCqJn8acj1toR44Om3YX3RHV6s_t-oB1qXBNocLHZn0Q/s1600/Pisanosaurus+New.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="599" data-original-width="1000" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiEDw_M9ZNg76qWuSeUuNHOR1ceKWZ9eqHTokVx9HF2ZhNdZXivhK9K2C_vmmQRgBQqLnUemEgdpUo9Nn1ysgpcX56xEcAuTCGCqJn8acj1toR44Om3YX3RHV6s_t-oB1qXBNocLHZn0Q/s320/Pisanosaurus+New.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Pisanosaurus</i> then (top) and now (bottom).</td></tr>
</tbody></table>
This implies a 30 million-year gap between <i>Pisanosaurus</i> and the earliest records of
ornithischians in unambiguously Early Jurassic sediments, like <i>Laquintasaura</i> and <i>Lesothosaurus</i>. This could mean several things:</div>
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<br />
<o:p></o:p></div>
<div class="MsoNormal">
1. Ornithischians are still a valid “suborder,” but were <i>ridiculously rare</i> components of their
ecosystems until after the Triassic-Jurassic extinction event, after which they
diversified rapidly;<o:p></o:p></div>
<div class="MsoNormal">
2. Ornithischians are a subgroup of Theropoda, branching off
after the Triassic-Jurassic extinction event. Animals like <i>Chilesaurus</i> make me think this might be a serious possibility.<o:p></o:p></div>
<div class="MsoNormal">
3. Phytodinosauria is real, but Ornithischia still didn’t
diversify until the Early Jurassic. Animals like <i>Chilesaurus</i> (which retains some weirdly sauropodomorph features)
make me think this might be a serious possibility.<o:p></o:p><br />
4. I sort of said this already, but some or all silesaurids could actually be basal ornithischians. This would force a lot of convergence with saurischians (Sauropodomorpha + Theropoda for the sake of argument).<br />
<br />
UPDATE: Baron gave a talk at SVP about <i>Chilesaurus</i> and Ornithoscelida and it sounds like things might be WAY crazier than we think based on what's currently published. But that's all I'll say.<br />
<br /></div>
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But whatever the answer, the point here is that there are no
more unambiguous Triassic ornithischian dinosaurs, which is really weird.<o:p></o:p></div>
<br />
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Oh, by the way, if <i>Pisanosaurus</i>
is a silesaurid, shouldn’t the group be renamed Pisanosauridae? After all,
Casamiquela (1976) considered <i>Pisanosaurus</i>
unique enough from other ornithischians that he gave it its own family, the Pisanosauridae.
Given the principle of priority, Pisanosauridae should have priority over
Silesauridae. However, the authors argue that Pisanosauridae has not been
employed for decades, whereas Silesauridae is well-known and widely accepted
today.<br />
<br />
Thus, “for the sake of clarity,” Agnolin & Rozadilla recommends
retaining Silesauridae. “Further,” they write, “it is probably best not to
abandon Silesauridae at least until further evidence definitively shows that <i>Pisanosaurus</i> belongs within this clade.”
I think they made a pretty good case already, but I also appreciate the clarity
argument. <o:p></o:p></div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com1tag:blogger.com,1999:blog-4675540394850433221.post-57976409201254517252017-07-17T14:29:00.001-07:002017-07-17T14:31:46.471-07:00The Saurosphargid That Wasn't<div class="MsoNormal">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_UrETVRrdACUYFt4XfiGrK-pnZt3X0JNdu7r-u3aQUNi-3WBW4C51JvQ4RPuVN-IbUx1uf1y2iIi7iOMSSTnTNNT0s_CrVTTjg3p5uhIxPkKHH0jumEMqS-cwl7deow_EbUZF6782m20/s1600/Derpophargis.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="638" data-original-width="825" height="247" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_UrETVRrdACUYFt4XfiGrK-pnZt3X0JNdu7r-u3aQUNi-3WBW4C51JvQ4RPuVN-IbUx1uf1y2iIi7iOMSSTnTNNT0s_CrVTTjg3p5uhIxPkKHH0jumEMqS-cwl7deow_EbUZF6782m20/s320/Derpophargis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Saurosphargid by Ethan Kocak</td></tr>
</tbody></table>
You might all remember that, some time ago, I introduced you
all to an obscure group of Triassic marine reptiles called <a href="https://waxing-paleontological.blogspot.com/2016/02/saurosphargids-primer.html">saurosphargids</a>. This
strange group of tubby critters includes just three genera: <i>Saurosphargis</i>, <i>Largocephalosaurus</i>, and <i>Sinosaurosphargis</i>.
Confusingly, Nosotti & Reippel (2003) named and described <i>Eusaurosphargis</i> under the assumption
that the original genus—<i>Saurosphargis</i>—was
a <i>nomen dubium</i> as the original (and
only) specimen of that taxon was destroyed during WWII.* Nosotti & Reippel
named it <i>Eusaurosphargis</i> even
though—according to their own analysis—<i>Eusaurosphargis</i>
was not a saurosphargid, but a sister taxon to <i>Hovasaurus</i>, a very different marine reptile from the Permian. They
could not decide whether <i>Eusaurosphargis</i>
was aquatic or terrestrial, but since it was routinely found to be closely allied
to Triassic marine reptiles, though, a life aquatic was the more obvious
choice.<o:p></o:p></div>
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</div>
<a name='more'></a><br />
<br />
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Now we seem to have a definitive answer, although it’s not
what you’d expect.<o:p></o:p></div>
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<br /></div>
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<a href="https://www.nature.com/articles/s41598-017-04514-x">Scheyer et al. (2017)</a> recently described a complete juvenile
specimen of <i>Eusaurosphargis</i> from
Switzerland. It’s a tiny, short-tailed, fat little critter that reminds me of a
horny toad (<i>Phrynosoma</i>). It’s also
very clearly terrestrial.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXnLA_QX6m1bOvbj1zpwhhtewZwaQE5jVszxtQpLcnI5tWhz46AkafiQtNOvzFSjRUfDVST0ClV2T_xhR2taqYhQPTIDT_4vKOdNrqDhqZdHyTUtHCwMkOqgh0DJAeO0ll5qgRdDRxoH4/s1600/Eusaurosphargis.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="609" data-original-width="675" height="288" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXnLA_QX6m1bOvbj1zpwhhtewZwaQE5jVszxtQpLcnI5tWhz46AkafiQtNOvzFSjRUfDVST0ClV2T_xhR2taqYhQPTIDT_4vKOdNrqDhqZdHyTUtHCwMkOqgh0DJAeO0ll5qgRdDRxoH4/s320/Eusaurosphargis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Notice the shingle-like osteoderms along the sides of the body.</td></tr>
</tbody></table>
<div class="MsoNormal">
Notably, <i>Eusaurosphargis</i>
has several rows of osteoderms along its body. There’s a central row of small
osteoderms which reaches from the neck to the tail, another row of small
osteoderms on either side of the central row, and a lateral row of much larger,
overlapping, single-shaped osteoderms on either side of the body, between the
fore- and hindlimbs. More osteoderms cover the forelimbs and the pelvis was
also covered with small plate-like osteoderms. This arrangement reminds me of <i>Largocephalosaurus qianensis</i>, really,
although that animal lacks the shingle-shaped lateral osteoderms.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDKWSgHFgEaZuz7srEZdoVZV06GlHmR7wmT2XBFzYAa68JiErgZeIrgE8VX7F0ggLHJPHj7OrsJMWy38kcuYm7gyXYI9lZ1I6HTWaSJp2Q3PmwMhDfrNfD4noFWbBpmm5V4efFfh5v1uo/s1600/Eusaurosphargis+Drawing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="864" data-original-width="720" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDKWSgHFgEaZuz7srEZdoVZV06GlHmR7wmT2XBFzYAa68JiErgZeIrgE8VX7F0ggLHJPHj7OrsJMWy38kcuYm7gyXYI9lZ1I6HTWaSJp2Q3PmwMhDfrNfD4noFWbBpmm5V4efFfh5v1uo/s320/Eusaurosphargis+Drawing.jpg" width="266" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fantastic reconstruction by Beat Scheffold</td></tr>
</tbody></table>
<div class="MsoNormal">
The authors compare the (disarticulated) skull of <i>Eusaurosphargis</i> to basal placodonts like
<i>Palatodonta</i> and <i>Paraplacodus</i>. The juvenile’s ischium is apparently similar to <i>Pararcus</i> (a placodont) and <i>Largocephalosaurus qianensis</i>; however,
the presumably adult holotype’s ischium has a very different shape. After some
discussion on the pros and cons of running phylogenies of Triassic marine
reptiles with or without obvious marine adaptations, Scheyer et al. find <i>Eusaurosphargis</i> as the sister taxon to
(Placodontiformes + Sauropterygia). <i>Helvicosaurus</i>,
thalattosaurs, and ichthyopterygians form successive outgroups of this
relationship.</div>
<div class="MsoNormal">
<br /></div>
<div style="text-align: left;">
</div>
<div class="MsoNormal">
But wait, you say, <i>Eusaurosphargis</i>
is terrestrial, but it’s surrounded by fully marine taxa. This incongruity does
not go unnoticed by the authors, who write that the “inferred terrestrial
lifestyle of <i>E. dalsassoi</i>…would thus
represent a reversal from aquatic habitats rather than retention of an
ancestral terrestrial condition.”</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO-xv9HLKAvhZwGwlQT3itzKTVUsAckoqUB8Zbc2c-DmTixbx_tvIelZODHGaYDVC0qeji0_Z9duhiCPB1xvfVQxur24OH1rw9wBRj9txcSVBd06V5R-ffQ6x3AhsRkG77VeI9vwjpI6I/s1600/Eusaurosphargis+Tree.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="364" data-original-width="675" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhO-xv9HLKAvhZwGwlQT3itzKTVUsAckoqUB8Zbc2c-DmTixbx_tvIelZODHGaYDVC0qeji0_Z9duhiCPB1xvfVQxur24OH1rw9wBRj9txcSVBd06V5R-ffQ6x3AhsRkG77VeI9vwjpI6I/s320/Eusaurosphargis+Tree.jpg" width="320" /></a></div>
<div class="MsoNormal">
Well, I mean, that’s not the only option. Look at your
outgroups—ichthyopterygians and thalattosaurs almost certainly took to the
water independently. Aside from its crazy tail, <i>Hovasaurus</i> looks perfectly at ease both in and out of the water.
Why assume that your marine superclade families were all ancestrally marine to begin
with? I think it’s also interesting that <i>Eusaurosphargis</i>
turns out to be the sister group of placodontiformes (which are armored) and
sauropterygia, since saurosphargids are also armored. Is it possible that <i>Eusaurosphargis </i>simply represents the
terrestrial ancestor of (Placodontiformes + Sauropterygia)?<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So there you have it. <i>Eusaurosphargis</i>
is not a saurosphargid and also isn’t aquatic.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<br />
<div class="MsoNormal">
*Hilariously, Scheyer et al. agree with Nosotti &
Reippel that ‘<i>Saurosphargis’</i> is a <i>nomen dubium</i>, and for largely the same
reasons. They disagree with Li et al. (2011) that Huene’s 1936 description is
sufficient to hang on to the genus, instead alleging that the description and
its accompanying photographs lack any diagnostic characters. If accepted, that
means “Saurosphargidae” must be abandoned as well, right?<o:p></o:p></div>
Zachary Millerhttp://www.blogger.com/profile/05035947146927565746noreply@blogger.com3