Hopeful Pterosaur(omorph)s

Lagerpetid by Rodolfo Nogueira

As we’ve seen, the Triassic was a period filled with all manner of charismatic animals, including reptilian platypuses and whales, praying mantis-like drepanosaurs, semi-aquatic dragons, pseudosuchian dinosaur mimics, 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, giant dicynodonts, 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.

Slightly More Hopeful Dinosaurs

Lewisuchus--basalmost ornithischian? (from Ezcurra et al., 2019)

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: silesaurids, Pisanosaurus, and the Triassic Ornithischian Crisis. Below, I will offer the briefest of recaps, but hit those links if you want a more complete picture.

Marine Snouters of the Triassic II: Gunakadeit Rising

Alaska's own Gunakadeit joseeae by the amazing Gabriel Ugueto, or @SerpenIllus on the Twitters.

A very long time ago, I posted an essay about one of my favorite groups of Triassic marine reptiles: thalattosaurs. These lizard-shaped swimmers, while generally similar in body form, differ from one another quite strongly in terms of feeding adaptations. While Anshunsaurus and Askeptosaurus may seem, to our modern eyes, rather vanilla in their clearly faunivorous dentition, others strain credulity. Xinpusaurus, 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. Thalattosaurus and its “claraziid” brethren have reduced, shell-crushing dentition and snouts which curve downward—Hescheleria 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.

Whale-Lizards of the Triassic III: Revenge of Eretmorhipis

You might fondly remember the two previous posts in this series: Part I and Part II 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: Nanchangosaurus, Hupehsuchus, Eohupehsuchus, Parahupehsuchus, and Eretmorhipis. Eretmorhipis 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 Parahupehsuchus although it's missing most of the tail, too.

Thanos Deserves Better

Thanos, the Mad Titan, disappointed with his namesake.

A new dinosaur was published today in Historical Biology: Thanos simonattoi, 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 Etrigansauria, an unnecessary name that has designs on replacing the perfectly-good Neoceratosauria. Delcourt & Vidoi lori (2018) identify Thanos as an abelisaurid close to Brachyrostra. This all seems fine until you see the holotype:

An Update on Stem Turtles

The beaky noggin of Eorhynchochelys by...IVPP?

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 way back in 2015 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.

Chilesaurus and Avian Arm Folding

Chilesaurus diegosuarezi by the impeccable Jaime Headden

Ever since the publication of supreme oddball Chilesaurus (eat your heart out, Halszkaraptor), I’ve been dying for somebody out there to do a full description of the critter’s unusual skeleton. As Chilesaurus 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—Ameghiniana—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.

The Saurosphargid That Wasn't

Saurosphargid by Ethan Kocak

You might all remember that, some time ago, I introduced you all to an obscure group of Triassic marine reptiles called saurosphargids. This strange group of tubby critters includes just three genera: Saurosphargis, Largocephalosaurus, and Sinosaurosphargis. Confusingly, Nosotti & Reippel (2003) named and described Eusaurosphargis under the assumption that the original genus—Saurosphargis—was a nomen dubium as the original (and only) specimen of that taxon was destroyed during WWII.* Nosotti & Reippel named it Eusaurosphargis even though—according to their own analysis—Eusaurosphargis was not a saurosphargid, but a sister taxon to Hovasaurus, a very different marine reptile from the Permian. They could not decide whether Eusaurosphargis 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.

The Long, Complicated History of Appalachian Ceratopsians

North America during the Campanian

The title is a joke. Finding ceratopsian remains east of Texas is an incredibly recent phenomenon. Oh sure, there are plenty of (fragmentary) dinosaurs known from the eastern half of the United States, but those taxa tend to be tyrannosauroids, nodosaurs, ornithomimids, and hadrosaurs. I should mention at this point that, during much of the Late Cretaceous, North America was cleaved into three islands by the presence of a shallow interior sea called the Western Interior Seaway (WIS): Laramidia to the west, Nunavut to the north, and Appalachia to the east. Laramidia’s eastern north-south shoreline is where we get most of North America’s dinosaurs—Alberta, Montana, Utah, and (to a lesser extent) Texas are all hotbeds of dinosaur action, and that includes ceratopsians.