This Ancient Reptile Had a Small Head, Tiny Eyes and a Platypus-Like Bill

Even paleobiologists find Eretmorhipis carrolldongi strange

Long Cheng, et al, Scientific Reports 2019, Creative Commons 4.0

Around ten years ago, the discovery of a incomplete fossil gave paleontologists their first look at a very strange creature that once swam through a vast lagoon in what is now Hubei Province, China. The extinct reptile, dubbed Eretmorhipis carrolldongi, was about two feet long, with a tail, four flippers and a series of stegosaurus-like plates lining its back. But the specimen was missing a rather important feature: the animal’s head.

In 2015, reports Nicholas St. Fleur of the New York Times, a more complete E. carrolldongi fossil was found. Experts were stunned by what they saw. E. carrolldongi, the discovery revealed, had a small head, tiny eyes and a big, cartilaginous bill—much like the modern-day platypus.

“When I first saw it, I just said ‘What?!’ and didn’t speak for a while,” Ryosuke Motani, a paleobiologist at the University of California, Davis, tells St. Fleur.

Motani and his fellow researchers describe the weird reptile, which lived some 247 million years ago, in a new paper published in Scientific Reports. Key among the questions they try to answer is how E. carrolldongi hunted.

E. carrolldongi is distantly related to ichthyosaurs, an extinct group of porpoise-like marine reptiles. But unlike many ichthyosaurs, which had large eyes to help them see prey in dark waters, E. carrolldongi’s eyes were very small. This probably means that the animal didn’t use sight to forage. No soft tissue was preserved in the fossil specimens, making it difficult for researchers to definitively say which sense E. carrolldongi relied upon instead. But the animal’s strange skeleton offers several clues.

It is unlikely, for instance, that E. carrolldongi was able to hear particularly well underwater. “[S]ound localization in water is difficult for animals with small heads,” the study authors write, “given that sound travels five times faster in water than in air.” E. carrolldongi also lacks the tell-tale palate structure of animals—like snakes—that use tongue-flicking to gather information about their surroundings.

So perhaps, the researchers posit, E. carrolldongi hunted much in the way that platypuses do: by using their ample snouts to find and scoop up prey in dark waters. Platypuses can also sense electric impulses generated by their prey; the study authors don’t know if E. carrolldongi shared this nifty ability, but it is “not impossible,” they write. The researchers add that E. carrolldongi probably ate shrimp and other small invertebrates, much like today’s duck-billed platypuses.

The recent study not only offers insight into an odd and little-understood ancient reptile, but also sheds new light on the period following the Permian mass extinction. During this devastating event, which occurred around 252 million years ago, more than 95 percent of marine and 70 percent of land species died off. Scientists once thought that the diversification of marine animals slowed in the wake of this disaster, but recent evidence suggests this was not the case. E. carrolldongi, which evolved in the aftermath of the extinction, certainly suggests that animals were diversifying rapidly.

“[T]here were a lot of open opportunities as life recolonized the Earth’s surface,” Motani tells Live Science’s Laura Geggel. This led to “bizarre forms” that “grabbed the open niches and diversified, but were soon wiped out, probably by natural selection,” he adds.

E. carrolldongi likely wasn’t a very efficient feeder, and it doesn’t appear to have been a fast swimmer either. “It wouldn’t survive in the modern world,” Motani says, “but it didn’t have any rivals at the time.”

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