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

在岐阜县船濑山地区的黑色粘土岩层中发现了印度（早三叠世）最早期牙形刺Hindeodus parvus和Hindeodus typicalis的自然组合。我用13种元素重建了这些物种的骨骼结构。研究结果表明，这些牙形刺生活在深海海底附近，死后直接埋藏在沉积物中。此外，本研究还调查了分布于日本栃木县秋山川地区的硅质粘土岩地层中的牙形石堆积层。该层含有Olenekian（早三叠世）牙形石物种。根据牙形刺的古生态和岩性特征，认为在远洋深海或远洋中层水中常产生缺氧状态。

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.