In Depth
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.
Further Reading
– The vertebrate fauna of the Selma Formation of Alabama. Part III. The turtles of the family Protostegidae. – Fieldiana: Geology Memoirs 3(3):63-133. – R. Zangerl – 1953.