A new study suggests that a recent discovery of a softshell turtle species that was excavated in North Dakota could be among the first of its genealogy. The animal belongs to the vast biodiversity that existed 66.5 million years ago, during the Cretaceous period.
Softshell Turtle Ancestors Among Dinosaurs
An imagined scene from the end of the Cretaceous Period, more than 66 million years ago, has the newly identified softshell turtle Hutchemys walkerorum dwelling alongside iconic species from the Age of the Dinosaurs.
Hutchemys walkerorum is theorized to have coexisted with other creatures during prehistory, such as the dominant groups of gigantic dinosaurs. Among the popular beasts that lived simultaneously as the softshell turtle were the Triceratops and Tyrannosaurus rex.
The discovery and identification of the animal's timeline contribute to the ever-expanding knowledge about the softshell turtles of prehistory and the impact of the end-Cretaceous mass extinction on their evolution.
Hutchemys walkerorum belongs under the vast chain of the Trionychidae family known as the plastomenines. The physiological appearance of these animals heavily resembles the modern-day softshell turtles. However, the bone armor that protects their abdomen and stomach, called the plastrons, is much larger and stronger than their existing cousins.
Plastomenines were able to survive the Cretaceous and Paleogene periods, which ran between 80 to 50 million years ago. The first fossil records identified from the group were the members from the Late Cretaceous. Their remaining branches lived throughout the Eocene epoch, peeking their diversity between the boundary of the Cretaceous-Paleogene.
University of Pennsylvania's Department of Earth and Environmental Science expert Steven Jasinski, who also led the study, explained that only a little information is known about the prehistoric softshell turtles up until recently. In the latest studies, numerous details are coming up regarding the particular turtle lineage, their evolutionary development, and how they survived the mass extinction of the time, he continued.
A Hutchemys walkerorum's partial carapace, commonly known as the turtle shell, was first unearthed back in North Dakota around 1975. This initial study was carried out by Appalachian State University experts John Callahan and Frank McKinney.
The first team excavated the ancient softshell turtle's fossils and the specimens of the famous Triceratops, PhysOrg reports.
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Hutchemys walkerorum and Late Cretaceous Mass Extinction
According to the study, the specimen from the Hutchemys walkerorum genus is an evident piece that could show a glimpse of the ages prior to the dinosaur extinction events. The genus of the animal was rarely recorded during the time, and only a few had been discovered straight from the Cretaceous period.
School of Veterinary Medicine specialist and coauthor Peter Dodson explained that the study of the prehistoric softshell turtle adds further information about the winning and losing populations during the end of the age of dinosaurs.
By comparing the ancient find with its known relatives, the Hutchemys walkerorum was categorized as a member of the Plastoimenini. Another group of early trionychids was discovered under a subfamily, Kuhnemydinae, and Chitrainae. The team concluded that the Trionychidae, a group under which the collective Hutchemys are, may have originated from Asia before they migrated to North America during the Late Cretaceous.
The study was published in the journal Cretaceous Research, titled "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."
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