A fossil leatherback sea turtle from the Bartonian of Kazakhstan

Abstract

The article describes fossil material of a leatherback sea turtle Dermochelyidae indet. from the Bayurbas and Sandy localities of the Shorym Formation (Bartonian, Middle Eocene) of the Mangyshlak Peninsula, Kazakhstan. The material is represented by cranial remains of one individual (Bayurbas) and an epithecal plate of the shell (Sandy). Dermochelyidae indet. from the Shorym Formation differ from all known dermochelyids in the morphology of the skull roof and the dentary. Based on the morphology of the epithecal plate, it is most similar to the representatives of the genera Cosmochelys Andrews, 1919 and Egyptemys Wood et al., 1996, whose skulls are unknown. The described cranial remains partially fill a large temporal gap (about 13.9 Ma) in our knowledge of the skull morphology of dermochelyids, between the oldest Ypresian species and the Rupelian Cardiochelys rupeliensis (Van Beneden, 1883). In addition, these are the first cranial remains of dermochelyids described from northern Eurasia (territory of the former Soviet Union).