Early Triassic Marine Reptile Had Platypus-Like Bill

Eretmorhipis carrolldongi, a 28-inch (70 cm) long marine reptile that lived about 250 million years ago (early Triassic epoch) in what is now China, likely used its platypus-like bill to hunt by touch.

Eretmorhipis carrolldongi had a long rigid body, a small head, tiny eyes and four flippers for swimming and steering. Image credit: Gianluca Danini.

Eretmorhipis carrolldongi had a long rigid body, a small head, tiny eyes and four flippers for swimming and steering. Image credit: Gianluca Danini.

Eretmorhipis carrolldongi was previously known only from partial fossils without a head,” said University of California, Davis’ Professor Ryosuke Motani.

“This is a very strange animal. When I started thinking about the biology I was really puzzled.”

Professor Motani and colleagues analyzed two nearly-complete specimens of Eretmorhipis carrolldongi from Yuan’an County, China.

The two fossils show the reptile’s skull had bones that would have supported a bill of cartilage.

Like the modern platypus (Ornithorhynchus anatinus), there is a large hole in the bones in the middle of the bill.

In the platypus, the bill is filled with receptors that allow it to hunt by touch in muddy streams.

First nearly complete specimen of Eretmorhipis carrolldongi, revealing an unusually small skull: (a) photograph; (b) outlines of the bones and impressions; (c) skeletal reconstruction, with flippers from the holotype. Scale bar - 5 cm. Image credit: Cheng et al, doi: 10.1038/s41598-018-37754-6.

First nearly complete specimen of Eretmorhipis carrolldongi, revealing an unusually small skull: (a) photograph; (b) outlines of the bones and impressions; (c) skeletal reconstruction, with flippers from the holotype. Scale bar – 5 cm. Image credit: Cheng et al, doi: 10.1038/s41598-018-37754-6.

In the early Triassic, the area was covered by a shallow sea, about a meter deep, over a carbonate platform extending for hundreds of miles.

The fossils of Eretmorhipis carrolldongi were found at what were deeper holes, or lagoons, in the platform.

There are no fossils to show what the ancient reptile ate, but it likely fed on shrimp, worms and other small invertebrates.

“Its long, bony body means that Eretmorhipis carrolldongi was probably a poor swimmer,” Professor Motani said.

“It wouldn’t survive in the modern world, but it didn’t have any rivals at the time.

Related to the dolphin-like ichthyosaurs, Eretmorhipis carrolldongi evolved in a world devastated by the mass extinction event at the end of the Permian era.

“The fossil provides more evidence of rapid evolution occurring during the early Triassic,” Professor Motani said.

The study was published in the journal Scientific Reports.

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Long Cheng et al. 2019. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Scientific Reports 9, article number: 152; doi: 10.1038/s41598-018-37754-6

 

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