A research team led by the University of Pennsylvania has recently described a new species of softshell turtle (Hutchemys walkerorum) that lived in North Dakota at the end of the Cretaceous Period, approximately 66.5 million years ago – just before the mass extinction that wiped-out the dinosaurs. Although the fossils – consisting of a partial carapace – were discovered in 1975 by a field crew from the Appalachian State University, they have only been properly analyzed and described now.
Hutchemys walkerorum roamed the Earth during the same period as large dinosaurs such as Tyrannosaurus Rex and Triceratops did. It belonged to a particular group of softshell turtles in the Trionychidae family called plastomenines which lived during the Cretaceous and Paleogene periods, approximately 80 million to 50 million years ago. Members of this group first appear in the fossil record during the Late Cretaceous, and were at their peak diversity before and after the Cretaceous-Paleogene boundary.
A phylogenetic analysis has revealed that this turtle belonged to a group of early trionychids (softshell turtles) in the subfamily Kuhnemydinae, which are fossil species from Asia. These findings suggests that the family Trionychidae originated in Asia before migrating to North America sometime in the Late Cretaceous. Although these turtles are similar to the softshell turtles that exist today, the bones covering their abdominal area were larger and more strongly sutured together.
“Until recently we didn’t understand these softshell turtles very well,” said study lead author Steven Jasinski, a paleontologist at Harrisburg University. “However, we are starting to get more information on this extinct group of turtles and further understanding their evolution, including how they dealt with the mass extinction.”
“With this study we gain further insight into winners and losers during the cataclysm that ended the Age of Dinosaurs,” added study senior author Peter Dodson, a professor emeritus of Paleontology at the University of Pennsylvania. “The mighty dinosaurs fell, and the lowly turtle survived.”
A detailed description of this specimen is published in the journal Cretaceous Research.
By Andrei Ionescu, Earth.com Staff Writer