Named By: Edward Drinker Cope - 1871.
Classification: Chordata, Reptilia, Testudines, Cryptodira, Protostegidae.
Species: P. gigas (type), P. advena, P. copei, P. dixie, P. eaglefordensis, P. potens.
Size: Larger specimens up to 3.4 meters long (nose to tail).
Known locations: Canada, USA, and United Kingdom.
Time period: Cenomanian through to Maastrichtian of the Cretaceous.
Fossil representation: Many specimens.
is one of the largest turtles to ever swim in the ocean and so far is
only eclipsed by Archelon
in terms of overall size. Like with
Archelon, Protostega is
thought to have had a ‘soft’ shell
similar to the modern leatherback turtle (Dermochelys
Also like with Archelon, Protostega
is thought to
have grown so
large by consuming a diet of soft organisms like jelly fish and
cephalopods. Protostega is usually associated
with parts of North
America that would have been under the Western Interior Seaway,
however other remains from England hint at a much more cosmopolitan
distribution for this turtle.
Despite the shell and large size, predatory marine reptiles like Tylosaurus, Mosasaurus and Hainosaurus would have posed a serious threat to Protostega. Additionally the shark Cretoxyrhina both grew large and had the teeth to go to work on a turtle.
- A description of the genus Protostega. - Proceedings of the Academy of Natural Sciences of Philadelphia: 422–433. - Edward Drinker Cope - 1872.
- The osteology of Protostega. - Memoirs of the Carnegie Museum, 2(7):279-305. - G. R. Wieland - 1906.
- Vertebrate Biostratigraphy of the Smoky Hill Chalk (Niobrara Formation) and the Sharon Springs Member (Pierre Shale). - High-Resolution Approaches in Stratigraphic Paleontology, 21: 421-437 - K. Carpenter - 2003.