大桑・万願寺動物とその変遷過程(<特集>日本海の生物相の変遷と環境変動-過去,現在そして未来へ向けて)

By the late Pliocene, endemic speciation occurred in the semi-closed Japan Sea. Such endemic species, which characterizes the Omma-Manganji fauna, diversified until the end of early Pleistocene. Warm-water current flowed into the Japan Sea since the early late Pliocene. Especially, the lower upper Pliocene yields some subtropical taxa which have been never recognized in the Recent Japan Sea. This warm-water inflow added subtropical to warm-temperate species to the Omma-Manganji fauna, but did not lead any endemic species to extinction. Cooling event at the Datum A (2.75Ma) also did not affect any endemic species. On the other hand, the Miocene relict species suffered from extinction by this cooling event. Moreover, some boreal species which is now living around Hokkaido and the Okhotsk Sea migrated southward to central Honshu by this cooling. In the ice age at the end of early Pleistocene, most of the endemic species suffered from extinction by brackish surface water and anoxic deep water conditions. These oceanographic condition also affected populations of other species, which disappeared in the Japan Sea and now live only in the Pacific side