The holotype of Iwakiella ichiroi Hatai, Kotaka and Noda, 1972, from the Permian Kashiwadaira Member of Northeast Japan is reexamined. Although previously placed within the Tentaculitoidea or retained in the Problematica, the possession of the septum and the spherical shape of the initial chamber suggest that this specimen belongs to sphaerorthoceratid orthocerid of the Cephalopoda. The present result confirms that the Tentaculitoidea probably became extinct near the Carboniferous – Permian boundary with Hidagaienites arcuatus Niko, 2000, as the latest representative.
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1 July 2022
Reexamination of a Permian Tentaculites-Like Fossil Iwakiella ichiroi Hatai, Kotaka and Noda, 1972, as an Orthocerid Cephalopod
Shuji Niko
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Paleontological Research
Vol. 26 • No. 3
July 2022
Vol. 26 • No. 3
July 2022
Northeast Japan
sphaerorthoceratid
Takakurayama Formation