The first report of fossil teeth of Heteroptychodus (Hybodontiformes: Elasmobranchii) from the Lower Cretaceous Kanmon Group in Fukuoka Prefecture, northern Kyushu, Japan

Abstract

Four fossil specimens of teeth belonging to the genus Heteroptychodus (Hybodontiformes: Elasmobranchii) are recorded as the first report of a fresh water elasmobranch from the Lower Cretaceous Kanmon Group. These specimens are yielded from two locations in the Fukuoka Prefecture, Kyushu Island, west Japan. These specimens are identified as Heteroptychodus steinmanni Yabe et Obata, 1930. The Heteroptychodus specimens from Japan are recorded from brackish or lacustrine sediments of Tokushima, Wakayama, Mie and Gunma Prefectures, and their geological age are limited in the Hauterivian to Barremian.