A discovery of ancient turtle bones in southern Utah has led a University of Texas paleontologist to identify a new species of long-extinct, pig-snouted turtle, according to a paper published today in the Journal of Vertebrate Paleontology.
Arvinachelys goldeni had a weird pig-like snout and lived in the shadows of Cretaceous dinosaurs. Image credit: Victor Leshyk.
Named Arvinachelys goldeni, the remains of the weird turtle were found in Grand Staircase-Escalante National Monument, Utah.
“The turtle’s scientific name derives from arvina, a Latin word for pig fat or bacon, and chelys, Latin for tortoise,” according to paleontologist Dr Joshua Lively, formerly of the Natural History Museum of Utah and now at the University of Texas at Austin, who is an author on the paper.
“And goldeni honors Jerry Golden, a volunteer fossil preparator at the Natural History Museum of Utah, who prepared the new holotype specimen.”
Arvinachelys goldeni lived in the Cretaceous period about 76 million years ago. The species grew up to two feet (60 cm) in length and lived in lakes and rivers.
Unlike any turtle ever found, its broad snout 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.
“It’s one of the weirdest turtles that ever lived,” Dr Lively said.
When Arvinachelys goldeni was alive, southern Utah looked more like present-day Louisiana. The climate was wet and hot, and the landscape was dominated by rivers, bayous and lowland flood plains.
It lived alongside tyrannosaurs, armored ankylosaurs, giant duck-billed dinosaurs such as Gryposaurus and Parasaurolophus.
Snout view of the skull of the fossil turtle Arvinachelys goldeni with its shell in the background. Most ancient turtle species are represented by fossil remains that often consist of nothing more than an isolated skull or shell. Arvinachelys goldeni includes not only the skull and the shell, but also a nearly complete forelimb, partial hindlimbs, and vertebrae from the neck and tail. Image credit: Natural History Museum of Utah.
The discovery also fills a gap in understanding the evolution of turtles.
During the time of Arvinachelys goldeni, western North America was a huge island continent, 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 seem to have diversified in isolation from their relatives in the northern part of the continent. The apparent confinement of the newly-discovered 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.
“The assumption has always been that organisms would be able to range over broad areas,” Dr Lively said.
“A combination of rising sea levels and persistent changes in the climate might have created barriers to dispersal during the Cretaceous period.”
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Joshua R. Lively. 2015. A new species of baenid turtle from the Kaiparowits Formation (Upper Cretaceous: Campanian) of southern Utah. Journal of Vertebrate Paleontology vol. 35. no. 6
