Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum No. 3

Fish otoliths from the Mizunami group are described and reported. Following genera are first reported in Japan; Uroconger, Rhynchocymba, Myripristis, ?Evynnis, Parapristipoma, Kuhlia, Umbrina. In addition, Myctophum, Diaphus, Lampanyctus, Sillago, ?Nibea, ?Gobius, Gobiidae, ?Pleuronectes, ?Solea, Soleidae.

The palaeo-climate is presumed to have been subtropical, because most of the fauna such as Kuhlia, Myriipristis, Solea, Gobius, Sillago, live mainly in the subtropical regions.

Judging from the otolith fauna, the sedimentary environment of the Togari, Yamanouchi members, and Shukunohora facies, is presumed to have been river mouth or shallow-sea; from the lithofacies and the benthonic molluscan assemblage,th e Nataki conglomerate member is composed of shallow sea sediments, but deep sea fossil otoliths, which is not derived-fossils, co-occur with shallow sea otoliths in it; from several facts, the author presumes that deep sea fishes, such as Uroconger, Myctophum, Diaphus, Jampanyctus, lived in the shallow sea during Miocene and Pliocene.