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.

Walk This Way

The right manus of Camarasaurus. Note the columnar arrangement and virtual absence of fingers.

Late last year, I introduced you all to the Lessemsauridae, a group of near-sauropod "prosauropods" that grew unreasonably large—up to 12 tons in Ledumahadi mafube. 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 Melanorosaurus and Barapasaurus.

Don't knock my Smok or I'll clean your clock!

We miss you, Bill Watterson.

A few months ago, I wrote that my favorite paleo story of 2018 was the publication of Lisowicia bojani, a ridiculously large dicynodont from Poland. In that same post, I mentioned Smok wawelski, a similarly-sized predatory archosaur of uncertain phylogenetic affinities that very likely hunted Lisowicia. It strikes me that Smok 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 Calvin & Hobbes strip because every time I hear the name Smok I immediately think of it.

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.

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.

Faux Theropods

The skeleton of Effigia

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 theropod mimics, and not just theropods but ornithomimosaurs. Ostrich dinosaurs in the Triassic...but suchians!

One More Strange Reptile

Remember my post from last year about azendohsaurs and trilophosaurs? Well just the other day, paleoartist extraordinaire Gabriel Ugueto posted a sketch of something called Teraterpeton. 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 Trilophosaurus. You'll notice that I did mention Teraterpeton 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--Teraterpeton is a perfectly good trilophosaur, and therefore an allokotosaur!

Adorable Triassic Pseudosuchians

Erpetosuchus sp. from North America

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 Parringtonia gracilis. 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 Erpetosuchus grandi, 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.

Very Specific Strange Reptiles

Azendohsaurus madagaskarensis by Matt Celeskey.

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 Trilophosaurus, I'll start this essay by discussing Azendohsaurus.

And Then There Were None

Today, we add an addendum to what’s turned out to be one of my favorite blog posts: Hopeful Dinosaurs. 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.

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.

Marine Snouters of the Triassic

The holotype of Thalattosaurus

When I started this humble blog in (dear lord) late 2014, I did not intend for it to becomes a blog dedicated to Triassic hellasaurs, but here we are. The more I read about the Triassic, the weirder it gets. For example, it seems like half of the reptiles alive during the Late Triassic were marine or at least semi-aquatic. We’re already covered hupehsuchians (twice) and those wonderful but woefully obscure saurosphargids. There was that recent post about underappreciated vancleaveans. Placodonts will come later and will probably spread across several posts—it was a big group. Today we’ll be talking about a diverse, well-known family of Triassic marine reptiles that still aren't well-known outside the paleo community: thalattosaurs.

Hopeful Dinosaurs - Updated!

Silesaurus opolensis, by Scott Hartman--used with permission.

We’re going to start this discussion with an assumption so that I don’t have to go back a hundred years and talk about the history of dinosaur phylogeny: Dinosauria is a monophyletic group, and it consists of the Saurischia (Theropoda + Sauropodomorpha) and Ornithischia (everyone else). I’ll also invoke Robert Bakker’s bizarre suggestion that the Theropoda was separate from a (Sauropodomorpha + Ornithischia) group he called the “Phytodinosauria” because they all ate plants, had similar teeth and, back in 1986, Segnosaurus was thought to be maybe a missing link between prosauropods and early ornithischians (details in The Dinosaur Heresies). You'll see why soon.

D&D Monsters of the Triassic

Alas, this is the biggest size I could find for this image.

We’ve already discussed some Triassic marine reptiles on this here blog: we talked about hupehsuchians HERE and HERE and then saurosphargids HERE and Atopodentatus HERE. Today, I want to talk about an emerging group of Triassic marine reptiles, one that only contains two genera (right now) and doesn’t even have an official name. I’m calling them "vancleaveans" and I expect full credit when that name is used later in actual paleontological literature.

Whale Lizards of the Triassic: Part II

A gorgeous new specimen of Hupehsuchus (ZMNH M8127).

When last we discussed Hupehsuchians, I ran down the known genera and went a bit into their lifestyle and phylogenetic relationships. The short version: these are small marine reptiles that are allied with ichthyosaurs in a monophyletic Ichthyosauriforms. They are long-snounted, toothless, filter-feeding creatures with closely-knit ribs and gastralia that form various degrees of “bony body tubes” across genera. They all lived around the same time, in the same place. Although they are taxonomically diverse, they are morphologically conservative.

Marine Lawnmowers of the Triassic

Sometimes you read a paper about a new fossil animal and just shake your head in disbelief. That was the posture I adopted back in 2014, when Atopodentatus unicus was unveiled to the world in the pages of Naturissenchaften. It’s a pretty good-sized marine reptile with a long tail and body, stout limbs, and a very small skull. From the neck down, this is a pretty nondescript critter that, according to its description, seems to have a close relationship with the Sauropterygia.

Tubby, Armored Sea Lizards of the Triassic

You may not remember, but I've briefly mentioned Saurosphargids before. In my hupehsuchian primer (that old chestnut), I tossed their name into the list of Triassic reptiles that were trying to make a name for themselves in a marine environment--perhaps to avoid becoming dinner for such the vicious rauisuchian pseudosuchians that were prowling the terrestrial environments. After doing some research, it turns out they are obscure to a fault--nobody's heard of them and there appear to be only four technical papers devoted to them. This should be an easy one, folks! Strap in and enjoy the ride. And stick around 'til the end for some fantastic art from Ethan freakin' Kocak of "The Black Mudpuppy" fame.

Monkey Lizards of the Triassic

Another exciting entry in the "Primer" series (which started with hupehsuchians)! Again, we're tackling a Triassic oddity. There are lots to choose from. Indeed, I sense a theme!

The Late Triassic was an exciting time in the history of life on Earth. Ecosystems were finally in full recovery after the brutal Permio-Triassic Extinction in which life nearly died, and the ancestors of modern groups were becoming established—this is where you find the great-great granddaddies of birds, mammals, and crocodilians. However, even though the world’s food webs and the roles within it were similar to today, the actual composition of those roles was much different. Mother Nature was going through a period of divine inspiration: the predator guild was ruled by large, vicious (distant) relatives of crocodiles—Postosuchus, Carnufex, and Teratosaurus—preyed on their own herbivorous relatives, the armored aetosaurs. These critters looked like a cross between an armadillo and a crocodile, but grubbed around on the ground for plants. The other big role in the herbivore guild went to the dicynodonts, therapsid holdovers from the Permian with tusked, toothless, beaked jaws, some of which grew to be the size of cows.