Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 47

Sandy and rocky shore molluscan fossils from the uppermost Lower Miocene Orito Formation on Sado Island in Niigata Prefecture, central Japan

Kazutaka Amano and Mitsuhisa Aida

Published: 2020/4/30   Page: 119

A total of 58 molluscan species was collected from the uppermost Lower Miocene Orito Formation at Kougasezaki, Sado Island, Niigata Prefecture. Fifty-two species, including six rocky shore gastropods are first recorded from the formation. Megacardita osawanoensis (Tsuda), Vepricardium okamotoi Taguchi, Timoclea itoigawae (Tsuda), Turbo (Marmarostoma) ozawai (Otuka), Haliotis notoensis Masuda and Littorinopsis miodelicatula Oyama are briefly described. These species suggest that the formation at Kougasezaki was deposited in the intertidal zone to 10–20 m depth, associated with a rocky shore environment.