ABSTRACT
The Sea of Japan has existed since Early Miocene time and the environmental conditions have changed during the Neogene and Quaternary geographically and oceanographically. The history of the Sea of Japan is generally divided into six stages, 1) the age of continental margin (Paleogene to Early Miocene), 2) the age of inception of a marginal sea and great transgression (late Early Miocene to Early/Middle Miocene), 3) the age of deepening sea (Middle Miocene), 4) the age of deep sea (Middle to Late Miocene), 5) the age of formation of present marginal sea (late Late Miocene/Early Pliocene) and 6) the age of present marginal sea (Late Pliocene to Recent). In the second stage the coastal shallow sea was mainly covered by tropical and subtropical elements of marine macrofaunas. In the fourth stage marine faunas and floras changed mainly to temperate elements of Pacific Ocean with rare subtropical elements. Between the fourth and fifth stages the shift of species in various taxa was well recognized. In the fifth and sixth stages the migration of marine organisms was actively carried out from the southern and northern seas. The change of marine macrofaunas were strongly effected by the exchange of warm and cold sea currents, and the appearance and disappearance of land-bridges and straits with the sea level changes caused by climatic and crustal movements.
