Monday, April 24, 2017

Thalattosaurs: Doin' Things With Snouts

The holotype of Thalattosaurus
Author's Note: I am still editing this post--mainly trying to find good links for references--but I needed to post this damn thing and get on with other research projects.

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.

Thursday, March 30, 2017

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.

Saturday, December 10, 2016

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.

Thursday, November 17, 2016

From the Triassic Monster Manual

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.

Wednesday, September 14, 2016

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.

Friday, July 29, 2016

Hupehsuchians 2: The Return

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.

Thursday, July 21, 2016

Book Review: Recreating an Age of Reptiles

I think we’re all familiar with the work of one Dr. Mark P. Witton. 

If you follow Mesozoic paleontology at all, you’ve probably read some of his papers (this one among many others) and you probably own his wonderful Pterosaurs book. Perhaps you even visited his inspiring 2010 pterosaur show in London. I have to imagine you read his excellent paleo-blog, too. 

Heck, maybe you’ve met him at SVP, perhaps back in 2009, when mutual friend Julia Heathcote introduced you but you were too intimidated and tongue-tied to say anything intelligent. I can tell you, from that brief encounter, that Dr. Mark P. Witton is the only person I’ve ever known who can successfully pull of an ascot.

Monday, May 9, 2016

Whatever The Hell This Thing Is: a Primer

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.

Monday, February 29, 2016

Saurosphargids: a Primer

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.

Friday, December 25, 2015

Drepanosaurs: a Primer

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.