New find of the Permian and Triassic fish Fossils in Japan : On the dermal denticles and teeth of fishes discovered from Karasawa area, southeast Asio Mountains

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  • GOTO Masatoshi
    東京支部:東京医科歯科大学歯学部第二口腔解剖学教室

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  • 本邦のペルム系および三畳系からの魚類化石群の発見 : 栃木県葛生町唐沢より産出したサメ類の皮歯および魚類の歯について
  • ホンポウ ノ ペルムケイ オヨビ 3ジョウケイ カラ ノ ギョルイ カセキグン

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Many fossil teeth and scales of fishes have been discovered from Japanese Permian and Triassic. The locality is Karasawa area, southeast Asic Mountains, and the horizon is black limestone stratum of Nabeyama formation (middle Permian; and laminated limestone stratum of Adoyama formation (Ladinian to early Carnian, Triassic; (Conodont Research Group, 1974). These fossils are found by the extraction of conodonts, associated with sponge spines, radiolaria and foraminifera, The writer observed these fossils by scanning electron microscope (Plate I). They consist of dermal denticles (placoid scales) of sharks and teeth and spines of fishes. The former indicates general morphology of dermal denticle of sharks which has three cusped crown (Fig. 1, 2). The latter includes various types, that is, lower coneshaped type (Fig. 4, 5), higher cone-shaped type (Fig. 7), type which has plication or striation on its crown surface (Fig. 10, 11) and dental plate type on which many teeth arrange alternately (Fig. 12). In addition to them, he observed a specimen which shows teeth-like structure on the longitudinal secticn(Fig. 8, 9). It is considered that these fish fossils will be one of the most important materials for the paleontological studies on the Paleozoic and Mesozoic vertebrates in Japan.

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