“Weird” is a relative term. The judgment only makes sense in the context of what’s familiar. We might think of a squirrel or a frog as weird if we had never seen one before. Still, there are some organisms that seem so downright bizarre and unlike anything else that it’s hard to resist the term. The ancient marine reptile Eretmorhipis carrolldongi is an excellent example.
Eretmorhipis is a recent addition to the prehistoric menagerie. This Early Triassic creature was named just a few years ago, in 2015. But like some other marine reptiles found from this time, it wasn’t immediately apparent just how bizzare Eretmorhipis is. A pair of new specimens have changed that, and, described by paleontologist Long Cheng and colleagues, some parts of the animal’s skeleton are reminiscent of a living animal many regard as strange.
In terms of family ties, Eretmorhipis is a hupehsuchian. These marine reptiles flourished during the early Triassic between 251 and 247 million years ago, but went bust seemingly as fast as they appeared. There wasn’t anything quite like them before, nor has there been since. Their skeletons look overbuilt, with densely-packed ribs, stiffened trunks, long tails and large paddles. But even among these unusual animals, Eretmorhipis stands out. Decorative blobs dot its back, and its skull looks ludicrously small compared to the rest of the body. More than that, Cheng and coauthors note, the eyes of the animal are tiny for its size, and there’s a strange space between the bones of the upper jaw. At least as far as the skull goes, Eretmorhipis shows a rough resemblance to today’s duck-billed platypus.
The itty bitty eyes, in particular, might offer some clues about the natural history of Eretmorhipis. Animals with such small eyes, Cheng and colleagues write, often do about their business in low-light conditions and may rely on other kinds of signals to go about essential business like finding food. The question is what Eretmorhipis did if it wasn’t relying on sight.
“Soft-tissues are not preserved in fossils in question, so it is impossible to explicitly test which non-visual sense of Eretmorhipis carrolldongi may have been enhanced,” the researchers write. Still, they note that extra sensitive hearing, tasting chemical signals in the water, and extra-sensitive smell are unlikely given that the anatomical markers for those traits are absent or not preserved. Perhaps other fossils will offer some new hints. Eretmorhipis evolved to be an oddity within a group of oddities, and we’re clearly just getting to know this unusual saurian.