Analyzing the remains found at the Arlington Archosaur Site, a site with various fossil remains from the late Cretaceous period in Texas, a team of researchers described four species of extinct turtles, one of which is named after paleontologist Derek Main.
This site was discovered in 2003 and proved to be a prolific location for late Cretaceous remains, remnants of life forms that lived more than 90 million years ago. It is a wetland located near the shore of a peninsula and already in the past has provided several fossils of ancient crocodiles, dinosaurs, mammals, amphibians, fish, invertebrates and even plants.
However, the turtle fossils discovered at this site had proved quite rare, at least until this study that was published in Palaeontology Electronica. The new species was named Trinitichelys maini. It is a Baenidae turtle, an extinct group of North American aquatic turtles that lived from the Cretaceous to the Eocene era.
Of medium size, these turtles showed strongly fused bones and upper shell and lived near rivers. The Trinitichelys maini is the oldest turtle of this group found in the North American subcontinent of Appalachia, a region that during the Cretaceous period was separated from Laramidia, the western subcontinent of North America.
In addition to the new classification, researchers described three other turtles, one of which is the oldest side-necked turtle (Pleurodira order) ever found in North America. These turtles are characterized by the particular way they withdraw their heads inside their shells: they do so by bending their necks on the horizontal plane.
The other two turtles described are one belonging to the group of trionichids (Trionychidae), or soft-shelled turtles, and another belonging to the genus Naomichelys (family Helochelydridae ).