Eons Roundup 11

It’s time for another batch of PBS Eons commission work!

The marine reptiles Atopodentatus and Henodus, from “The Triassic Reptile With ‘Two Faces'”
https://www.youtube.com/watch?v=-8W26SiCylI


The marine turtles Archelon and Euclastes, from “The Return of Giant Skin-Shell Sea Turtles”
https://www.youtube.com/watch?v=Tmb8XCwb3FI

Eons Roundup 7

It’s another PBS Eons commission roundup day!

The metatherian mammals Pucadelphysand Khasia, and lineart of the sparassodont Paraborhyaena, from “How South America Made the Marsupials”
https://www.youtube.com/watch?v=l5doyrUWFbE


The dyrosaurid crocodyliform Acherontisuchus and the bothremydid turtle Puentemys, from “How a Hot Planet Created the World’s Biggest Snake”
https://www.youtube.com/watch?v=T-hDNbM-WLk


The early penguin Waimanu and the giant penguin Anthropornis, from “When Penguins Went From The Sky To The Sea”
https://www.youtube.com/watch?v=HMArjGQwLvY

Chupacabrachelys

Bothremydids were an extinct group of side-necked turtles that existed from the late Cretaceous to the early Miocene, between about 100 and 20 million years ago. Found across most of the world (with the exception of Antarctica and Australia) they were a diverse group occupying a range of ecological niches, inhabiting both freshwater and near-shore marine habitats.

Although their fossils are mainly just fragmentary remains like pieces of shell, Chupacabrachelys complexus here is actually known from a fairly complete skeleton.

Living in what is now western Texas, USA, during the late Cretaceous (~75 mya), it was an average-sized member of the group at around 1m long (3’3″) and was probably marine, swimming around in the shallow tropical waters of the Western Interior Seaway.

It had a particularly unusual skull for a turtle, narrow and triangular and slightly flattened, with elongated eye sockets. The paleontologists who described Chupacabrachelys thought the overall shape was vaguely reminiscent of a canid, and so that ended up inspiring its name — a reference to the mangy coyotes that are occasionally mistaken for the mythical chupacabra.

Anomalochelys

Anomalochelys angulata, a terrestrial turtle from the mid-Cretaceous of Hokkaido, Japan (~100-94 mya).

Measuring around 60cm long (2′), it had a pair of large forward-facing horn-like spikes at the front of its shell – the function of which isn’t clear, but they may have been useful for defense if it was incapable of fully retracting its head into its shell.

It was part of a family of turtles from Asia and North America known as nanhsiungchelyids, a group that adapted to live fully on land and ended up convergently closely resembling modern tortoises. Other members of this group included the larger Nanhsiungchelys (which was also recently found to have possessed “horns” on its shell!) and the very flat Basilemys.

They were also a rare example of a turtle family that didn’t survive through the end-Cretaceous mass extinction, with no known remains from the Cenozoic.

Alienochelys

Alienochelys selloumi, a sea turtle from the Late Cretaceous of Morocco (70-66 mya). Although only known from a single skull, it was probably around 2-2.5m long (6′6″- 8′2″), and was closely related to both the modern leatherback turtle and the giant Archelon – and so it wouldn’t have had a solid shell but instead a leathery skin-covered carapace.

But that one skull was also incredibly weird. While most turtles have pointed beaks, Alienochelys had a blunt squared-off face, sort of “pug-nosed”, with its nostrils set high up between its eyes. It seems to have been specialized for crushing hard-shelled prey between the wide flat grinding surfaces of its beak, more similar to the jaws of rays than those of other turtles.

It also lived alongside another bizarre-jawed turtle, but that’s a subject for another time.