New material of sirenian fossil from the upper Miocene of Numata-cho, Hokkaido, Japan

Abstract

New material of sirenian fossil was recognized from the upper Miocene of Numata-cho, Hokkaido, Japan. This specimen belongs to the genus Dusisiren of the subfamily Hydrodamalinae, because of its size of vertebrae and ribs. Another genus of the Hydrodamalinae, Hydrodamalis spissa, has been found from the lower Pliocene of this area before (Furusawa et al., 1990). Detailed relationship of these specimens and the evolution of North Pacific sirenia may be clear by new specimens from this region in the future.