A team of scientists has identified a new species of softshell turtle named Hutchemys walkerorum , which lived in what is now North Dakota (United States) about 66.5 million years ago, which places its existence at the end of the Cretaceous period, shortly before the mass extinction event during the Late Cretaceous period.
Lived at the same time as T. rex
The most iconic species of the Age of Dinosaurs during the Cretaceous period, such as the Triceratops or the Tyrannosaurus rex, would have lived with this creature that could be among the first in its genealogy.
“Until recently, we didn’t understand these softshell turtles very well. However, we are beginning to learn more about this extinct group of turtles and better understand their evolution, including how they coped with mass extinction,” he said. Steven Jasinski, from the Department of Earth and Environmental Sciences in the School of Arts and Sciences at Penn University and lead author of the study that has been published in the journal Cretaceous Research.
What was this prehistoric turtle like?
Although the fossils, which consist of a partial shell, were discovered in 1975 by an Appalachian State University field team, they have not been properly analyzed and described until now. The specimen was housed at Appalachian State University until 2013. And research on the fossil began in earnest at this time.
Phylogenetic analysis of the remains 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 suggest that the Trionychid family (which includes 33 species of turtles and thrived during the Cretaceous and Paleogene periods some 80 to 50 million years ago) originated in Asia before migrating to North America sometime in the 19th century. Upper Cretaceous.
Thus, Hutchemys walkerorum belongs to a particular group of softshell turtles called plastomenines. They are similar to the softshell turtles that we see today, although the plastron of plastomenina turtles, the bones that cover the stomach and abdominal area, is better sutured and is larger and more robust than in other softshell turtles. .
Members of this group first appear in the fossil record during the Late Cretaceous and reached their maximum diversity before and after the Cretaceous-Paleogene boundary.
According to the study, the specimen from the genus Hutchemys walkerorum is an obvious piece that could show a glimpse of the eras before the extinction events of the dinosaurs.
“With this study, we learn more about the winners and losers during the cataclysm that ended the Age of the Dinosaurs. The mighty dinosaurs fell and the humble tortoise survived,” says co-author Peter Dodson.
The authors’ analysis also led to the formation of a new classification within the family Trionychidae : a subfamily called Chitrainae that comprises all modern softshell turtles, including the narrow-headed and softshell giant tortoises, such as the giant tortoise. Asian softshell ( Pelochelys cantorii ) found in South Asia.
Denomination
Hutchemys walkerorum ‘s name honors Greg and Susan Walker who, as philanthropists, led them to create The Greg and Susan Walker Endowment Awards in 2006 to provide resources for Earth and environmental science students to conduct independent research projects as part of their study plans.
“The Greg and Susan Walker Endowment awards research support, typically for projects costing up to $5,000, in response to proposals submitted to the endowment through the Department of Earth and Environmental Sciences, ” clarifies Professor Robert Giegengack. .
Referencia: Steven E. Jasinski, Andrew B. Heckert, Ciara Sailar, Asher J. Lichtig, Spencer G. Lucas, Peter Dodson. A softshell turtle (Testudines: Trionychidae: Plastomeninae) from the uppermost Cretaceous (Maastrichtian) Hell Creek Formation, North Dakota, USA, with implications for the evolutionary relationships of plastomenines and other trionychids. Cretaceous Research, 2022; 135: 105172 DOI: 10.1016/j.cretres.2022.105172
