Family Dermochelyidae (superfamily Chelonioidea) from the Upper Cretaceous of north Japan

Mesodermochelys undulatus, a new genus and species, is described as the best Mesozoic representative of the Dermochelyidae (order Testudines, superfamily Chelonioidea). This new taxon is described from 15 specimens which include cranial fragments, lower jaw, axial and appendicular skeleton, and a nearly complete shell. These specimens were collected from the Lower Maastrichtian, Upper Cretaceous of Hobetsu-cho, Central Hokkaido, North Japan. Frequent occurrence of this primitive dermochelyid in the Upper Cretaceous of Japan suggests endemic distribution among Mesozoic chelonioid species.