Turnersuchus - Blog Posts
these all look phenominal!
Results from the #paleostream! Turnersuchus, Batrachognathus, Platyhystrix and Kundurosaurus. Some details might confuse you here. I explain below.
The Batrachognathus here are flying around a curious structure, a "Steinerne Rinne", a rare occurrence in which small, calciumhydrogencarbonat rich creeks over time turn into natural aqueducts because of moss and algae taking the Co2 out of the water. Limestone comes out and encrusts the moss.
Platyhystrix is not only shown with an osteoderm-only-sail but also producing spermatophores. Some modern day salamanders do this after a mating dance instead of the usual watery copulation.
The last scene shows a Kundurosaurus unsure about the situation it is in. It has it's nest next to a blue lava stream. Blue lava is created by high concentrations of burning sulfur on the surface.
Turnersuchus: First of the Sea Crocs
A big find for crocodile finds was revealed two days ago. Turnersuchus hingleyae (Hingley's and Turner's crocodile) is the oldest known and basalmost thalattosuchian described so far and is of great importance to slowly figuring out where thalattosuchians come from.
But lets start with a brief introduction to thalattosuchians. As the name already suggests, thalattosuchians are primarily known to have been marine animals (tho exceptions are known). thalattosuchians can broadly be split into two groups. The teleosauroids, which look somewhat similar to what one might call a normal crocodile, and the metriorhynchoids, which especially in the derived members could aptly be described as crocodile mermaids. Below an example of each, on the left Macrospondylus by Nikolay Zverkov and on the right a generalized metriorhynchid by Gabriel Ugueto.
Thalattosuchians such as these two groups, which are sister clades and not successive lineages (so they co-occured rather than one having evolved from the other), were incredibly successful during the Jurassic, evolving enormous forms such as Plesiosuchus, Dakosaurus and Machimosaurus. Their wild success held on throughout the Jurassic until they eventually went extinct in the early Cretaceous. But despite how common and whidespread they are, we don't actually have much of a clue where they come from. Thalattosuchians just kinda appear during the Toarcian and are already found across multiple continents with both groups established. To complicate matters, their position among crocodiles is also rather shaky. Three main hypothesis exist. One is that they are a sister group to crocodyliforms (Protosuchians, Notosuchians and Neosuchians), that they are basal mesoeucrocodylians or that they are Neosuchians related to Pholidosaurids (like Sarcosuchus) and Dyrosaurs.
This is where Turnersuchus comes in. Discovered in the Charmouth Mudstone Formation of Dorset, England, this genus is known from the skeletal material belonging to the back of the head, mandible, parts of the forearms and shoulder girdle as well as neck, body and tail vertebrae all preserved in five blocks and a few isolated pieces of bone. From that we can already see general similarities to derived thalattosuchians and basic traits like narrow jaws and reduced forelimbs (tho not nearly as extreme as in metriorhynchids).
The first significant part about this discovery is its age. Turnersuchus is from the Pliensbachian stage of the Jurassic, so it predates any previously diagnostic thalattosuchians. Secondly is its position. As I said above, thalattosuchians are divided into teleosauroids and metriorhynchoids. But Turnersuchus is neither, with both phylogenetic analysis finding it to fall outside of these groups. Now in fairness this is not rock solid, as there is only a single trait excluding it from the derived groups in either analysis, so future works might shake things up. But as things are right now, it's the oldest named and basalmost member of the entire clade. On a sidenote at least the oldest part is bound to change, as the paper mentions a Moroccon teleosauroid currently in press that is even older.
All of this allows for two things. For one, by comparing Turnersuchus with the basal members of both teleosauroids and metriorhynchoids scientists were able to gather a list of traits that appear to be ancestral to the group. In addition, Turnersuchus also preserves some features that separate it from all other thalattosuchians that are also indicative of being an early member. Just as one example a specific part of the basioccipital thats associated with long skulls is poorly developed, which means that while slender the jaws weren't as long as in some later thalattosuchians. A Bayesian analysis was also conducted in an attempt to nail down when thalattosuchians evolved. Now depending on which phylogeny is used (one with thalattosuchians as non-crocodyliforms and another with them as mesoeucrocodylians) you get different times. The former would place their origin in the Norian stage of the Triassic, the later in the Sinemurian stage of the Jurassic. In light of the Moroccon material alluded to by the paper, it would appear that they likely split from other crocodylomorphs sometime in the late Triassic.
And finally to wrap this up let me share the press release artwork to finally give a face to all this information. Now if you've read my post about fossil crocs of 2022 you might already recognize the artist, as she's been on a real streak with illustrating fossil crocs. If you don't know her, I highly recommend checking out her work. I'm of course talking about Júlia d'Oliveira.
And yes, of course I got the Wikipedia page for it ready. Tho with work getting in the way when it was published I almost feared I'd be unable to get to it first.
