Osteopygis sp.
The Zilker Park Turtle

Incomplete carapace and plastron
TMM 43190-1
Edwards Formation, Cretaceous
Travis County, Texas

Turtles are an ancient lineage of reptiles that arose long before the dinosaurs appeared and they have survived until the present day.  Most turtles live on land or in freshwater streams and lakes, but some have become adapted to life in the oceans.  Osteopygis is one such marine species.  It lived in the shallow seas that covered much of Texas during the Cretaceous, living together with animals like Mosasaurus and Polyptychodon.  Osteopygis may have grown to about 5 feet in length, but it was by no means the largest of the Cretaceous turtles.  There were others that reached more than twice the size of Osteopygis, and skeletons of these giants have also been found in Texas.

The specimen that is buried at the Dino Pit was discovered by a hiker in Zilker Park.  The specimen was collected by paleontologists from the Vertebrate Paleontology Laboratory of the Texas Natural Science Center.  Much of the bottom half of the shell (plastron) and a few pieces of the shell´s upper half (carapace) were preserved in this specimen.  It is unusual because it was found on the same layer of rock that preserved several nearby dinosaur tracks.  If the entire shell and skeleton had been found, it would have represented a large animal, weighing several hundred pounds.  Like other marine turtles, it probably ate fish, squid, and other marine animals.