Santonian-Campanian Neoselachian Faunas of the Upper Cretaceous Yezo Group in Nakagawa Town, Hokkaido, Japan

Fifty-one fossil shark teeth, including Hexanchiformes, Echinorhiniformes, Squaliformes and Lamniformes, are described from two localities in Nishichirashinai and Omagari formations of the Yezo Group in Nakagawa Town, Hokkaido, Japan. They include the first occurrence of Protosqualus from the northwestern Pacific and suggest the onset of the adaptation to deep-water environments of the Squaliformes in this region by early Campanian. Different sedimentary settings of the two localities may have caused different taxonomic compositions. The co-existence of Hexanchiformes and Lamniformes is also known in a contemporaneous Japanese fauna and those of southern high latitudes and suggests effects of paleogeographic settings on the global distribution of Upper Cretaceous neoselachian taxa.