日本の新生代淡水魚類相

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On the origin of the freshwater fish fauna of the Japanese Islands, zoogeographers have adopted the hypothesis of the invasion of the Continental Asiatic fauna in relatively recent ages. According to this hypothesis, the invasion took place mainly in Late Pliocene. This hypothesis based on the distribution of the living fish fauna, and the distribution of the continental shelf and the submarine valleys seem to support this idea. Another support to this hypothesisis the idea of colonization of the new fauna by way of penetration through the lower stream contact during the low sea level stages in the Quaternary period. From scarcity of the fossil remains in Japan, zoogeographers have been liable to depend almost exclusively on the data of the present day fauna which often reflects geohistorical phenomenon of the relatively late ages. As for the problems concerning to geological scale of time such as the origin of farna, the facts should be asked for first among fossil remains. In the present paper, the authors offer the data of the fresh water fish fossils discovered in various parts of Japan. As is the case of the Continental West Eurasia, the occurrence of remains becomes frequent in Neogene. But in the case of the Japanese Islands, it becomes decidedly numerous in the Earliest Miocene basins, which distributed along the Japan Sea coast. On the other hand, it becomes seldom in the later stages of sedimentation, and almost unknown from the earlier ages. This concentration which took place during the Green Tuff Orogenesis. The first explosional development of the fresh water teleostean fauna in East Asia must have taken place in this time along the south-eastern coast of the Angara Continent. During the Pliocene period, lakes were widely developed along the Setouchi Sedimentation District, however, the Pliocene sequence in this district is almost devoid of fossil fishes. The Miocene fresh water fish fauna in Japan differs largely from the one which now distributed in Japan. On the generic level, however, the former approaches much to the one now distributed in the Continental East Asia. Investigating the fossil fishes collected up to date, the authors incline to conclude that, the two cyprinid subfamilies, Xenocypridinae and Cyprininae, were the dominant fish groups in the Neogene fresh waters of Japan, and at least a part of this ancient fauna existed until Middle Quaternary in Japan. Although the present contribution is not comprehensive as to the origin of the recent fauna of Japan, yet it should be noted that at least some typical species on subspecies of the modern Japanese fauna already existed before the beginning of Pliocene.
日本地質学会の論文
1977-02-21

日本の新生代淡水魚類相

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