著者

Umeda Masaki

出版者

日本古生物学会

雑誌

Paleontological research (ISSN:13428144)

巻号頁・発行日

vol.2, no.2, pp.96-107, 1998-06-30

参考文献数

20

被引用文献数

3

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This paper focuses on ceratoikiscid radiolarians from the Devonian Nakahata Formation of the Yokokurayama Group in the Kurosegawa Terrane. The fauna is assigned to the Emsian to Eifelian (late Early to early Middle Devonian). There are 13 species of radiolarians, including 4 new species, which belong to the genera Ceratoikiscum, Glanta, Protoholoeciscus, Circulaforma and Helenifore. The morphology and stratigraphic distribution of the genera suggest that Protoholoeciscus evolved from Ceratoikiscum via Glanta with the process of acquisition of shell.