Name: Protostega ‭(‬first roof‭)‬.
Phonetic: Pro-toe-steg-ah.
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.
Diet: Carnivore.
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.

       Protostega 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 coriacea‭)‬.‭ ‬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.

Further reading
- 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.


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