Eretmorhipis carrolldongi, a hupehsuchian marine reptile from the Early Triassic of China (~247 mya).
This species was originally named back in 2015, but at the time the only known specimens were missing their heads. It was assumed that its skull would have looked similar to those of other hupehsuchians… but now new fossils have been found, and it seems to have actually been much much weirder!
Eretmorhipis’ head was surprisingly tiny in proportion to its body – sort of like a marine version of Cotylorhynchus – and its shape convergently resembled the modern platypus, with a wide “duck bill” and very small eyes. It may have hunted for food along the seafloor in a similar manner to the platypus, using either a highly sensitive sense of touch or possibly even electroreception to locate small invertebrates like worms and shrimp.
It also had much larger bony osteoderms than its other known hupehsuchian relatives, forming a distinctive protruding spiky ridge down its back. At about 85cm in length (2′9″) it was one of the largest marine animals around at the time, so this structure probably wasn’t needed for defense – but as with other hupehsuchians its actual function is still unknown.
In early 2017 evidence of blubber was found in plesiosaurs, indicating that they were probably much more chubby than they’re usually reconstructed, and now in late 2018 it’s been found in an ichthyosaur, too!
Living during the Early Jurassic (~183-179 mya) in the shallow seas that covered most of Europe at the time, Stenopterygius was an average-sized ichthyosaur growing up to about 4m in length (13′). A fossil found in Germany has some incredibly good soft-tissue preservation, showing smooth flexible scaleless skin, a layer of insulating blubber very convergently similar to that found in cetaceans, and even evidence of countershaded coloration.
While the confirmation of blubber is amazing, and gives further evidence that ichthyosaurs were warm-blooded, the color preservation might actually be even more interesting. The skin pigmentation is preserved in enough fine detail for branched melanophores to be visible under a microscope – a type of cell associated with the ability to change color. So there’s a possibility that ichthyosaurs could actively darken or lighten their color patterns, for purposes such as better camouflage, UV protection, or temperature regulation.
Paludidraco multidentatus from the Late Triassic of Spain (~237-227 mya).
This 3m long (9′10″) animal was a member of the nothosaurs, a group of semi-aquatic seal-like marine reptiles that were closely related to plesiosaurs (and both were also evolutionary cousins to modern turtles).
It had long slender jaws full of numerous tiny teeth, creating an interlocking comb that was probably used for filter feeding – scooping up mouthfuls of fine-grained sediment from the seafloor and filtering out small invertebrates or soft plant matter.
The bones of its skeleton were also highly thickened and dense, a condition known as pachyostosis that provided ballast to weigh it down in the water. This would have made it a slow and unmaneuverable swimmer, but a very energy-efficient one, using its natural neutral buoyancy to hover or walk along the seabed.
It was essentially a reptilian manatee, filling a similar sort of ecological niche.
Thalattosaurs were a weird and rather mysterious group of Triassic marine reptiles. It’s not clear where they actually fit on the reptile evolutionary tree (we know they’re diapsids, but nobody can really agree on anything more definite than that), and they had some very strange skulls that seem to have been highly specialized for something, although their actual function is still unknown.
Xinpusaurus kohi here is known from the Late Triassic of China (~232-221 mya). About 1.3m long (4′3″), with half of that being its paddle-like tail, it had an elongated upper jaw that formed a protruding pointed spear-shaped snout.
It’s not clear whether this odd snoot was an adaptation for hunting similar to the long bills of swordfish – there’s quite a bit of variation in length and shape between different individual specimens – or if it was serving some other purpose like the sexually dimorphic noses of some modern lizards.
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.
Sclerocormus parviceps, an unusual ichthyosauriform from the Early Triassic of China (~248 mya).
Its short toothless snout suggests it was a suction feeder, using water pressure differences to pull small soft-bodied prey straight into its mouth like a syringe. Along with a heavily built body similar to those of hupehsuchians, and a very long tail that made up over half of its 1.6m length (5′3″), it was probably a fairly slow swimmer living in shallow coastal waters.
It was a close relative of Cartorhynchus, and may have been similarly capable of hauling itself onto land like a modern pinniped.