By Will Dunham
WASHINGTON (Reuters) - In shallow warm seas about 247 million years ago in what is now China, an oddball marine reptile flourished in the aftermath of Earth's worst mass extinction, possessing a duckbilled snout and unusually small eyes that made it resemble a platypus.
Scientists on Thursday described fossils of the three-foot-long (one metre) creature, called Eretmorhipis carrolldongi, that boasted a head that looks too little for its body and weak vision that indicates it relied upon a sense of touch, not sight, to forage in murky water using its cartilaginous bill.
Eretmorhipis, previously known only from headless skeletons before new fossils were unearthed in Hubei province, appeared early in the Triassic Period in the wake of a mass extinction 252 million years ago, possibly caused by immense Siberian volcanic activity, that erased roughly 90 percent of species at the end of the Permian Period.
"It has this very strange combination of features," said paleontologist Ryosuke Motani of the University of California, Davis, also including four big flippers, triangular bony blades on its back and a stiff, bony body trunk.
"A person seeing it would probably say, 'Bizarre,' or, 'How weird.' I think I said, 'What?' when I first saw it," Motani added.
Researchers have documented a quick and dynamic rebound in marine ecosystems in a time of evolutionary experimentation after the die-off as new creatures filled ecological niches vacated by extinct ones, facing little competition.
"You did not have to be optimally tuned to survive. If this species was introduced to today's ecosystem, it would not stand a chance of survival," Motani said.
Eretmorhipis, which lived roughly 17 million years before the first dinosaurs, superficially resembles a duckbilled platypus, the primitive, semi-aquatic, egg-laying mammal from Australia. The bone structure supporting the bill in both creatures is similar, as is the reduced eye size.
This is an example of a phenomenon called convergent evolution in which unrelated organisms acquire similar characteristics in adapting to similar environments, often separated by many millions of years, Motani said. Another example is birds, bats and the extinct flying reptiles called pterosaurs all evolving wings for flight.
A slow-moving predator, Eretmorhipis probably foraged at dusk or night for soft invertebrates like worms and shrimp. It was closely related to ichthyosaurs, a marine reptile group that arose about 249 million years ago and disappeared about 90 million years ago.
Eretmorhipis is the oldest creature and only marine reptile known to have had a bill. While its bill also superficially resembles that of a duck, its underlying structure is considerably different.
The research was published in the journal Scientific Reports.
(Reporting by Will Dunham; Editing by Sandra Maler)