Named By: Rainer Zangerl - 1953.
Synonyms: Protostega advena.
Classification: Chordata, Reptilia, Testudines, Cryptodira, Protostegidae, Chelospharginae.
Species: C. advena (type).
Known locations: USA - Alabama - Selma Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Possibly few specimens.
Chelosphargis was originally named as species of Protostega in 1906 by Oliver Perry Hay. However the description of Calcarichelys in 1953 led a later palaeontologist, Rainer Zangerl to conclude that P. advena should be reclassified as a distinct genus. Chelosphargis is regarded as being almost identical to Calcarichelys, a turtle with a series of large spines down the middle of its shell, with the only distinct difference between them being the formation of the keel in Chelosphargis.