Before the great extinction, an ancient soft-bodied turtle lived next to the dinosaurs

(ORDO NEWS) — Paleontologists have described a new species of so-called soft-bodied turtles that lived side by side with tyrannosaurs and triceratops at the very end of the Mesozoic era.

The newly discovered reptile belongs to the genus Hutchemys, which, unlike its dinosaur contemporaries, successfully survived the cataclysm that marked the beginning of a new Cenozoic era.

Scientists managed to describe a new species of ancient turtles – Hutchemys walkerorum . The animal lived on the territory of modern North Dakota (USA) 66.5 million years ago, immediately before the great extinction that killed all dinosaurs.

Previously, paleontologists already knew a number of species of the same genus Hutchemys , but they had a rather vague idea about these animals.

The new sample made it possible to understand the evolution of not only this genus, but also a number of its relatives from the group of so-called soft -bodied turtles ( Trionychoidea ).

These animals are perfectly adapted to the aquatic lifestyle: the shell is streamlined and covered with skin, and the limbs are capable of rowing movements.

In Cretaceous ecosystems, the neighbors of Hutchemys walkerorum were such Mesozoic “stars” as Tyrannosaurus Rex and Triceratops. However, at the turn of the eras – the Mesozoic and the Cenozoic that continues to this day – the great extinction wiped out all dinosaurs, other large reptiles and many other species from the face of the Earth.

At the same time, tortoises of the genus Hutchemys managed to survive into the Cenozoic, only to become extinct in the Paleocene, a few million years later.

The new find helped to understand how these turtles were affected by the disappearance of many neighbors in the process of extinction. Steven Jasinski, who recently received his PhD in Earth and Environmental Sciences from the Pennsylvania State University (USA), is interested in this.

Curiously, these Mesozoic reptiles are similar to modern soft-shelled turtles. However, their plastron – the ventral shield of the shell, which is formed by fused bones – was larger and stronger.

Scientists have assigned the genus Hutchemys to a distinct small group called the Plastomenines . Its representatives flourished from the Cretaceous period to the Paleogene, that is, 50-80 million years ago.

Several representatives of Hutchemys are described in deposits of the late Cretaceous period, and the only one – the latest – is known from the Eocene. The ancient soft-bodied turtles reached their greatest diversity just at the time when the great Cretaceous-Paleogene extinction occurred.

“Until recently, we didn’t really understand these turtles very well,” said Steven Jasinski, one of the authors of the new article in Cretaceous Research . “However, now we are learning more about this extinct group and better understand their evolution, including how they managed to survive during the mass extinction.”

Stephen and his colleagues are studying a fossilized specimen of Hutchemys walkerorum , which is a fragment of a carapace, the dorsal shield of a turtle’s shell formed by fused bones.

The fossil was extracted from the rock back in 1975 in North Dakota. It is curious that the same expedition also discovered the remains of Triceratops, so both species of reptiles could quite literally be both neighbors and contemporaries.

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