May 11, 2016

by Jennifer Viegas

An animal described as part Dr. Seuss, part dinosaur has been identified as being the first known plant-eating marine reptile.

The reptile, which lived 242 million years ago in southern China, arose after the planet's largest mass extinction, revealing that dire times can result in animals with seemingly improbable features.

The crocodile-sized plant eater, named Atopodentatus unicus, aka "Uniquely Strangely Toothed," is described in the journal Science Advances.

Senior author Nicholas Fraser of National Museums Scotland told Discovery News, "To me, it is very much in keeping with a Dr. Seuss creation!" said Senior author Nicholas Fraser of National Museums Scotland, adding that the Seuss tale, "The Things You Can Think" comes to mind.

Fraser and his team studied the fossils for the reptile, with a particular focus on what was previously thought to be a flamingo-like beak. The new analysis instead found that the "beak" was part of a hammerhead-shaped jaw apparatus that the reptile used to feed on plants on the ocean floor. Peg-like front teeth lined the jaw, which also had needle-shaped teeth. None of the teeth were suitable for eating meat.

Some sharks today have hammerheads, but their sharp teeth are definitely ready to sink into moving prey such as octopus and even other sharks.

Co-author Olivier Rieppel of Chicago's The Field Museum said that the marine reptile's peg teeth were used "to scrape plants off rocks on the seafloor, and then it opened its mouth and sucked in the bits of plant material. Then it used its needle-like teeth as a sieve, trapping the plants and letting the water back out, like how whales filter-feed with their baleen."

The teeth are reminiscent of those of certain dinosaurs, such as plant-eating Nigersaurus. The body of A. unicus seemed to be dinosaur-like as well, given the creature's long neck and rather chunky mid section.

While the lineage of A. unicus is a mystery for now, the researchers speculate that it was an "aberrant sauropterygian." These were aquatic reptiles that developed from terrestrial ancestors at around the time of the Permian-Triassic extinction event 252 million years ago. Sauropterygians include plesiosaurs that, like A. unicus, breathed air, had flippers and often long necks.

http://news.discovery.com/animals/very-strange-animal-was-first-marine-plant-eater-160506.htm