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Xavier A. Jenkins

@semifossorial.bsky.social

Paleontologist and postdoc at the American Museum of Natural History. I study tetrapod origins, sensory evolution, and all things Permian🦎🐢🐊

183 Posts757 Follower297 Folgt
Tiago Simões@trsimoes.bsky.social · 2w ago

Proud to share our latest paper in out in Nature today on the origin of #snakes. We present Tametara mirim, an articulated 3D preserved stem snake from the Late Cretaceous of Brazil. Tametara helped us re-tell the story of snake origins in a novel way... www.nature.com/articles/s41...

Exceptional brain and ecological diversity in the earliest snakes - Nature

A well-preserved fossil snake from the Late Cretaceous of Brazil shows early ecological and brain shape disparity in the group.

nature.com

Matt Friedman@friedmanlab.bsky.social · 2mo ago

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.

Illustration of many fishes swimming in sunlit blue water.
Dr. Jaimi Gray@jaimiagray.bsky.social · 3mo ago

The Pacific spiny lumpsucker, an inefficient swimmer but a highly efficient suction cup. The pelvic fins have evolved into a strong suction disk on the belly, giving it the ability to anchor itself to substrates. Plate-like structures called "tubercles" provide defense against predators.

A 3D model made from a micro-CT scan of a Pacific spiny lumpsucker, with the skeleton rendered in light brown/beige and the tubercles rendered in a gradient of colors, beginning with pink at the head, and changing from purple, to blue, to teal as you move towards the tail. Outline of the body is rendered in white and transparent. Shown in antero-lateral view (top), anterior view (bottom left), and left lateral view of the head (bottom right). Scale bar at the bottom right is 5 mm.A 3D model made from a micro-CT scan of a Pacific spiny lumpsucker, with the skeleton rendered in light brown/beige and the tubercles rendered in a gradient of colors, beginning with pink at the head, and changing from purple, to blue, to teal as you move towards the tail. Outline of the body is rendered in white and transparent. Shown in dorsal view (top), right lateral view (middle), and ventral view (bottom). Scale bar at the bottom left is 10 mm.
J Pardo@jdpardo.bsky.social · 5mo ago

A couple years ago, we reported one from even further south, in Namibia. A giant early tetrapod with affinities to species of tetrapod from the earliest Carboniferous, which we named Gaiasia. But is Gaiasia unique only to the far south, or was it part of a Gondwana-wide fauna?

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Cy Marchant@slvrhwk.bsky.social · 6mo ago

Very excited to share Scyllacerta creanae, a new Permian stem-reptile from South Africa known from an aggregation of several individuals. This specimen provides unprecedented detail regarding the anatomy of the early reptile skull. 🦎 (1/🧵)

Graphic illustrating the reconstruction process for Scyllacerta creanae (SAM-PK-K7710). The holotype aggregation specimen (left) comprises four skulls and at least six nearly complete skeletons preserved in lifelike positions. Using synchrotron micro-CT scans of the skulls, the bones could be segmented, digitally isolating them from the matrix and allowing their full morphology to be studied in detail (top center). Combining information from all four skulls, a reconstructed version could be assembled, depicting the likely life appearance (center, with each bone in a distinct color). This reconstruction can be used to make line drawings for science communication and skeletal reconstructions (bottom center). These reconstructions were the basis for a detailed life restoration of the head of Scyllacerta (bottom right, by @LiterallyMiguel). Despite its incredibly small size (top right, compared to a human hand), the known individuals were likely nearing full maturity.
Robert Gay@paleorob.bsky.social · 6mo ago

First paper of 2026 is out for #FossilFriday, and the first of probably several ornithischian papers over the next interval. Here my coauthors and I describe some tantalizing bits that suggest that ornithischian diversity in the Morrison Formation is higher than previously recognized.

The first page of the paper described in the post.
Owen Goodchild@paleowen.bsky.social · 7mo ago

peerj.com/articles/204... My first mammal project, which I started as an REU intern at the AMNH is finally published! Huge thanks to my mentors and coauthors on this project for all their help, and to the reviewers for their comments and suggestions!

The petrosal and bony labyrinth of extinct horses (Perissodactyla, Equidae) and their implications for perissodactyl evolution

Perissodactyla, or odd-toed ungulates, are represented today by 16 species of rhinoceroses, tapirs, and horses. Perissodactyls were much more diverse in the past, having a rich fossil record spanning ...

peerj.com