Classification, evolution, and paleoecology of the Permian to Triassic conodonts based on a natural assemblage

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Natural assemblages of Hindeodus parvus and Hindeodus typicalis, the earlymost Induan (Early Triassic) conodonts, were recovered from the black claystone beds distributed in the Funabuseyama area, Gifu Prefecture. I reconstructed the skeletal architecture of these species with 13 elements. It was found from the result of this study that these conodonts dwelt near a deep sea floor and were buried directly in the sediments after their death. Conodont-accumulated layers in the siliceous claystone beds distributed in the Akiyamagawa area, Tochigi Prefecture, were also investigated in this study. The layer bears the Olenekian (Early Triassic) conodont species. On the basis of the conodont paleoecology and lithology, it was concluded that an anoxic condition was often produced in a pelagic deep sea or pelagic intermediate water.