Osteopygis  Osteopygis is a genus of extinct turtle. "Osteopygis", as traditionally seen, is a chimera: the postcrania (including the holotype) belong to a non-marine stem-cryptodire, whilst the crania belong to sea turtles. In 2005 the referred material was split between two taxa: the postcrania remained in "Osteopygis", while the crania were reassigned to "Euclastes wielandi".