Pronounced (pro-toe-stay-gah gi-gus)
Discovery Location: MuseumRockwell County, Texas
Period: Late Cretaceous
Age: 83 million years
Formation: Taylor Group
Width: 15.5 feet between flippers
Location of Original Specimen: Dallas Museum of Natural History
Protostega gigas is an extinct genus of turtle that lived approximately 65-98 million years ago. It is the second largest turtle that ever lived, second only to Archelon. Fossilized Protostega remains are rare.
The Protostega head is extremely large, compared to the Archelon. It had a large, unprotected area between the head and body. As turtles evolved, their shells grew closer to their heads to provide greater protection to their shoulder and neck areas.
The shell was not solid. It was made of a thick web of bone, which served to reduce its weight. The spiky look of the plastron (lower shell) is very apparent on this skeleton.
Like their descendents today, these ancient sea turtles could not retract their bodies into their shells. They used their huge front paddles for a quick and powerful undersea get away to defend themselves from predators.