Current state of research on Quaternary freshwater fossil fishes in Japan

Abstract

Quaternary freshwater fish fossils are significant to consider the biogeographical history and evolution of Recent and Neogene freshwater fishes. In the present study, previous studies of Quaternary freshwater fish fossils from Japan are reviewed with the updated geological datum of each fossil bed. In Japan, Pleistocene sediments (e.g. Kobiwako Group) have yielded many pharyngeal teeth of cyprinids as well as spines and bones of siluriformes, which contribute to paleobiogeographical and histological studies of these taxa, although the fossils are fragments. Fish fossils from the Miyajima Formation of Tochigi and the Nogami Formation of Oita could possibly be utilized to calibrate molecular clocks of molecular phylogenetics, because these can be identified at the species level based on the articulated and well-preserved fossil specimens. Studies of fish bones and scales from shell mound remains of the Jomon period revealed the existence of extinct cyprinid groups of present Japan and regional extinction during the Holocene time in Japan. These studies are important to discuss the relationships between the transition of fish fauna and human activities.