Itilochelys rasstrigin gen. et sp. nov, a new hard-shelled sea turtle (Cheloniidae sensu lato) from the Lower Paleocene of Volgograd Province, Russia

Abstract

Itilochelys rasstrigin, gen. et sp. nov., a new hard-shelled sea turtle (Cheloniidae sensu lato), is established based on a partial skull, two lower jaws, a humeral bone and cervical vertebrae I–III from the Lower Paleocene of Volgograd Province, Russia. Itilochelys rasstrigin differs from other cheloniids s.l. by the following combination of characters: (1) long skull; (2) short snout; (3) deep cheek emargination; (4) frontal contributing to orbital margin; (5) prefrontal/ postorbital contact absent; (6) long anteroventral process of postorbital; (7) extensive secondary palate; (8) moderate vomer length on triturating surface; (9) deep and narrow midline groove on triturating surface through vomer length; (10) swellings lateral to midline groove present; (11) long lower jaw symphysis; (12) concave lower triturating surface; (13) blunt and shallow symphyseal ridge ending in a triangular elevation; (14) lingual ridges on the lower jaw absent. The new taxon increases diversity of stem-cheloniids and represents the most complete finding of these turtles in Russia.