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New review paper with Martín Ezcurra just published in @journalsystpal.bsky.social as part of a special issue! Modern reptiles comprise archosaurs 🐊🦉, lepidosaurs🦎🐍, and turtles🐢, but their origins is murky. Where do turtles fit in, really? And most marine reptiles? Choristoderes? Drepanosaurs? ->

Reconstructed skull of Eunotosaurus africanus, an early reptile from the Permian of southern Africa. 🐢 Long hypothesized to be an ancient ancestor of turtles, recent work led by @semifossorial.bsky.social shows this curious creature is instead a 'turtleized' millerettid. (1/🧵) #FossilFriday

I feel like this is going to be a constant narrative for a while now

Gosh. Would love an anatomy-heavy documentary. But maybe the target audience is too niche? (writing our pitch now)

Dimetrodon's Daydream #berensart2026 #paleoart

🔵🟠KNICKS IN 5!*🟠🔵

A fossil thought to be key to turtle evolution turns out to be something else - which clarifies where our shelly friends came from. Today’s free newsletter is out (short article + my latest writing + upcoming events + ear perks from the week).

Led by the incomparable Sanaa El-Sayed, a study out today in Science Advances throws open an important new window on marine fish diversity during the critical few million years following the K-Pg mass extinction. Below: artistic vision of the new fauna by Ian Baylatry.

New paper. Modern hagfishes (Myxiniformes) have radically reduced eyes. When did these reductions happen, and how? Leveraging the diverse hagfish fauna from Mazon Creek, we show this happened gradually in animals occupying shallow marine environments royalsocietypublishing.org/rsbl/article...

It means we should really revisit some of of the more recent hypotheses on an exclusively burrowing origin of the turtle shell. We should look at Triassic turtles more closely! 👀

The skeletal reconstructions in our paper are by @slvrhwk.bsky.social and @literallymiguel.bsky.social , and the amazing Gabriel Ugueto @serpenillus.bsky.social brought Eunotosaurus back to life. 😃

Huge thanks to ALL of my coauthors here, who all contributed to this project in significant ways. This work would not have been possible without our South African colleagues and the utterly amazing fossil collections there.

So, long story short: soft tissues, molecules, and fossils are now in agreement… turtles are close relatives of archosaurs. 🐢

To be thorough, we used constraint analyses to test all other alternative hypotheses of turtle origins, including with extinct groups such as captorhinids, pareiasaurs, and even living lepidosaurs 🦎. Each of these hypotheses are statistically rejected.

When we incorporate all of this into a phylogenetic analysis of 962 characters, the result is unambiguous: Eunotosaurus is a millerettid. Turtles (Pantestudines) are among the earliest relatives of archosaurs.

And those T-shaped, overlapping ribs? That were supposed to be strong support for Eunotosaurus-as-a-turtle? We show that they’re present in another millerettid from South Africa: Milleretta rubidgei. In fact, both Eunotosaurus and Milleretta develop these broadened ribs during ontogeny.

The secondary closure of the upper temporal fenestra - the key feature used to link Eunotosaurus to turtles and crown reptiles - turns out to be a diagnostic feature of Millerettidae, first recognized in 1957, and further documented by us last year.

Instead, it shares a suite of braincase and skull roof features that are nearly identical to millerettids…. the very group some researchers had allied it with before the turtle hypothesis took over again.

Our data also show that braincase of Eunotosaurus is unlike any fossil turtle. It’s even more primitive than all known neodiapsids, a group living and fossil reptiles known from the late Permian onward.

We re-segmented the skull of CM-777 and revisited EVERY specimen of Eunotosaurus present in South African collections, as well as the holotype in the UK. Our segmentation shows some key differences, for instance, the ‘supratemporal’ of recent studies is just the parietal.