Tiny eyes make a bizarre, ancient platypus-like reptile even weirder | Science News

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How Bizarre

Tiny eyes make a bizarre, ancient platypus-like reptile even weirder

The creature lived about 250 million years ago

By
9:00am, January 24, 2019
ancient marine reptile

SMALL-EYED SWIMMER  Two new fossils of the ancient marine reptile Eretmorhipis carrolldongi (one shown at top; outline below) are the first to include the animal’s skull.

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My, what tiny eyes you had, Eretmorhipis carrolldongi.

Two newly found specimens of the mysterious, platypus-like reptile suggest that the ancient creature had very small eyes for its size, and may have hunted mainly by touch. That makes E. carrolldongi the oldest known amniote — a group that includes reptiles and mammals — to use a sense other than sight to find its prey, scientists report online January 24 in Scientific Reports.

E. carrolldongi, which lived about 250 million years ago, is one of numerous strange creatures dating to the Early Triassic described by scientists in recent years. It is part of an oddball array of marine reptiles called Hupehsuchia that lived in a vast lagoon spanning hundreds of kilometers across what’s now central China. That flourishing of forms, which came on the heels of the mass extinction at the end of the Permian Period 252 million years ago, suggests that marine reptiles diversified millions of years earlier than once thought, the researchers say.

E. carrolldongi was named in part for its large, fan-shaped flippers, which give its body a passing resemblance to a platypus (Eretmorhipis means “oar fan”). Now, the newly discovered specimens, the first with skulls, point to one more thing that the ancient swimmer had in common with the modern platypus: very small eyes.

The creature also had a small head, meaning that it probably didn’t use hearing to forage, given the challenge of localizing sound in water. Chemoreception — used by snakes, for example, to gather information from the atmosphere through their tongues — is also unlikely based on the lack of certain telltale holes the skull, say paleontologist Long Cheng of the Wuhan Centre of China Geological Survey and colleagues.

By elimination, the researchers suggest that E. carrolldongi probably used tactile cues, such as hair cells that can help an animal detect movement, to stalk its lagoon prey. Still, electroreception, in which predators sense electric fields generated by moving prey, can’t be ruled out, the scientists say. And that would be one more thing it had in common with platypuses — they use electroreception, too.

Citations

L. Cheng et al. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Scientific Reports. Published online January 24, 2019. doi:10.1038/s41598-018-37754-6.

Further Reading

C. Gramling. A four-legged robot hints at how ancient tetrapods walked. Science News Online, January 16, 2019.

C. Gramling. Volcanic eruptions that depleted ocean oxygen may have set off the Great Dying. Science News Online, December 6, 2018.

S. Milius. Oldest known lizard fossil pushes group’s origins back 75 million years. Science News. Vol. 193, June 23, 2018, p. 6.

T. Sumner. Lack of nutrients stalled rebound of marine life post-Permian extinction. Science News Online, August 22, 2016.

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