Bulletin of the Mizunami Fossil Museum

Bulletin of the Mizunami Fossil Museum Vol. 51, No. 1

Speciation, extinction and survival of molluscan species in the marginal sea -Plio-Pleistocene Omma-Manganji fauna in the Japan Sea borderland-

Kazutaka Amano

Published: 2024/12/25   Page: 75109

The PlioPleistocene Omma-Manganji fauna shed light on the mechanism of speciation, extinction and survival in the Japan Sea. The semi-enclosed Japan Sea accelerated speciation by interrupting gene flow since the Late Miocene. During some cold events such as NHG, MIS 22 and LGM, most shallowwater species became extinct because of cooling and reduced salinity. In addition, many deepsea species became extinct because of anoxia. Some large-sized bivalves such as pectinids and some predator gastropods such as buccinids were vulnerable because of their high metabolic rates and cold conditions. On the other hand, some species dwelling in the intermediate marine zone (200 to 300 m in depth) could survive the deteriorated environments in the glacial periods.