Washington: Scientists have discovered a new species of extinct turtle with a weird pig-like snout that lived alongside dinosaurs 76 million years ago in Utah.
The turtle discovered in Grand Staircase-Escalante National Monument by a team from the Natural History Museum of Utah is one of the most complete skeletons of a turtle found from the age of dinosaurs.
"It's one of the weirdest turtles that ever lived," said Joshua Lively, a doctoral student at the University of Texas at Austin, who studied the fossil while he was at the University of Utah.
The extinct turtle was about 2-feet-long from head to tail. Its streamlined shell was adapted for living in a riverine environment, the researchers said.
When it was alive, 76 million years ago during the Cretaceous Period, the climate in Southern Utah was wet and hot, and the landscape was dominated by rivers, bayous and lowland flood plains.
It lived alongside tyrannosaurs, armoured ankylosaurs, giant duck-billed dinosaurs such as Gryposaurus and Parasaurolophus, and other dinosaurs that left abundant fossil remains in the Upper Cretaceous Kaiparowits Formation of Southern Utah.
Unlike any turtle ever found, the broad snout of the newly discovered species has two bony nasal openings. All other turtles have just one external nasal opening in their skulls; the division between their nostrils is only fleshy.
The pig-nosed turtle has been named, Arvinachelys goldeni, in honour of Jerry Golden, a volunteer fossil preparator at the Natural History Museum of Utah, who prepared the new holotype specimen - and many others in the museum's collections.
The new specimen includes not only the skull and the shell, but also a nearly complete forelimb, partial hindlimbs, and vertebrae from the neck and tail of Arvinachelys.
The discovery fills a gap in understanding the evolution of turtles.
During the time of Arvinachelys, western North America was a large island continent named Laramidia. A sea stretching from the Arctic to the Gulf of Mexico separated Laramidia from eastern North America.
During the Late Cretaceous Period, dinosaurs of southern Laramidia (southern Utah, New Mexico and Texas) seem to have diversified in isolation from their relatives in the northern part of the continent (Montana and Alberta).
The apparent confinement of Arvinachelys and other species of turtles to southern Laramidia fits that same pattern.
It remains a mystery what kept northern and southern populations isolated from each other.
A combination of rising sea levels and persistent changes in the climate might have created barriers to dispersal during the Cretaceous Period, researchers said.
The study was published in the Journal of Vertebrate Paleontology.