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.

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.

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.

The Rise & Possible Immediate Fall of the Ornithoscelida

Last week, the world was stunned by a new paper by Baron, Norman & Barrett (2017) that challenged Seeley's 130-year-old dichotomy of the Dinosauria. No longer were Saurischia and Ornithischia neatly separated. Instead, ornithischians were the sister group of theropods in a united Ornithoscelida, and sauropodomorpha (which now included Herrerasauridae as its most basal member) were spun off on their own in a weirdly lonesome Saurischia.

I spent several days writing a very lengthy post about this subject, as I considered it interesting and important. I also haven't really found the thesis statement for my WIP article on 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.

Titanosaur Heads

Illustration by "Stocktrek Images, Inc."

Sauropods are among the most familiar of all dinosaurs—consider that pretty much everybody knows Brontosaurus or Brachiosaurus. But what may surprise you is that most sauropods are known from fairly scant remains—isolated vertebrae or pieces of the axial skeleton. Brontomerus was named for, essentially, an incomplete ilium and scapula. Argentinosaurus, one of the largest tetrapods that ever lived, was named for a series of vertebrae, ribs, and a fibula. But you know what’s most often missing from a sauropod skeleton? The head.

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.