Extinct Pig-Snouted Turtle Discovered In Utah Sheds Light On Evolution, Researchers Say

Scientists from the Natural History Museum of Utah recently discovered an ancient turtle species unlike any other ever found, and it may help researchers fill in the gaps of turtle evolution. Unlike other turtles that have a single nasal opening in their skulls, the broad snout of the newly discovered species, scientifically known as Arvinachelys golden, has two bony nasal openings, according to a news release. 

"It's one of the weirdest turtles that ever lived," Joshua Lively, one of the study's researchers who was working on his master's thesis at the University of Utah at the time, explained in a statement. "It really helps add to the story emerging from dinosaur research carried out at the Natural History Museum of Utah."

All other turtles have just one external nasal opening in their skulls, and the division between their nostrils is only fleshy, researchers explained in their study. This biological difference observed in Arvinachelys acts as a benchmark that researchers can now use to piece together how turtles have evolved throughout their 250-million-year evolution. 

Fossils of the pig-snouted turtle were originally excavated from the Grand Staircase-Escalante National Monument in southern Utah. Researchers were able to recover the skull, shell, a nearly-complete forelimb, partial hind limbs, and vertebrae from the neck and tail of Arvinachelys, according to the release. This specimen represents one of the most complete skeletons of a turtle from the Age of Dinosaurs. 

"With only isolated skulls or shells, we are unable to fully understand how different species of fossil turtles are related, and what roles they played in their ecosystems," Randall Irmis, curator of paleontology at the museum and associate professor at the University of Utah, said in the release. This fossil, however, paints a clearer picture. 

After analyzing the fossils of this extinct turtle species, researchers discovered that it was approximately two feet long from head to tail and was adapted to living in river environments. Also, the species was dated to be 76 million years old, which means it was alive during the Cretaceous Period.

During this time, southern Utah looked more like present-day Louisiana, the researchers explained in their study. The climate was hot and wet, with rivers, bayous and lowland flood plains dominating most of the landscape. Arvinachelys would have also lived alongside dinosaur species such as the tyrannosaurs, armored ankylosaurs, and the giant duck-billed dinosaurs Gryposaurus and Parasaurolophus, the release noted. 

Previous studies indicate that it was during this time that many species diversified in isolation from their relatives. Researchers suggest this could have resulted from rising sea levels or climate change, which could have caused natural barriers between species. Nonetheless, fossil evidence of Arvinachelys and other species of turtles follow the same evolutionary pattern, which could explain why modern turtles developed only one external nasal opening. Understanding what species were alive and what physical adaptations they had developed to cope with their environment helps researchers better interpret what ecosystems may have been like during the Late Cretaceous, researchers explained. 

Understanding such adaptations will help researchers better predict how modern species will cope with future climate change. Their findings were recently published in the Journal of Vertebrate Paleontology.

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