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The cephalic skeletal structure of Jurassic “Eucyrtidium” (Radiolaria)

Published online by Cambridge University Press:  14 July 2015

Atsushi Takemura
Affiliation:
Department of Geology and Mineralogy, Faculty of Science, Kyoto University, Kyoto 606, Japan
Kojiro Nakaseko
Affiliation:
Institute of Geological Sciences, College of General Education, Osaka University, Toyonaka 560, Japan

Abstract

Almost all nassellarians possess some skeletons, comprised of cephalic skeletal elements, at the base of their cephalis. Observations using the scanning electron microscope (SEM) have been made on the internal structures of Jurassic “Eucyrtidium” from manganese carbonate ore deposits in the Mino Terrane, central Japan. Jurassic “Eucyrtidium” possesses only a median bar and apical spine as cephalic skeletal elements. Because this structure is quite different from that of Cenozoic Eucyrtidium, which possess MB, A, V, L, l, and D, a new genus, Monosera, is proposed for the Jurassic forms. One new species, Monosera gujoensis, is described.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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