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Revision of the pseudoniscine merostome genus Cyamocephalus Currie. American Museum novitates ; no. 2557

Show simple item record Eldredge, Niles. en_US Plotnick, Roy E. en_US 2005-10-06T18:21:22Z 2005-10-06T18:21:22Z 1974 en_US
dc.description 10 p. : ill. ; 26 cm. en_US
dc.description Includes bibliographical references (p. 10). en_US
dc.description.abstract "We present an emended diagnosis for the monotypic genus Cyamocephalus Currie, 1927, based on examination of the holotype of Cyamocephalus loganensis and study of a second, very well-preserved specimen we attribute to Cyamocephalus cf. C. loganensis. Both specimens, which were collected from Upper Silurian rocks of Great Britain, are described in detail. The holotype specimen is remarkable in that a pair of dark stains, the possible remains of a portion of the dorsal longitudinal muscle system, are preserved within the cardiac lobe of the prosoma and the axial lobe of the opisthosoma. The prosomal morphology of Cyamocephalus is similar to that of other pseudoniscids; as in other Pseudoniscidae, cardiophthalmic morphology is obscure but similar in general plan to that of other Limulina. There are 10 opisthosomal segments; the first (anterior) segment is greatly reduced with very short pleura. Segments 2-10 have well-developed pleura, and segments 6 and 7 are fused into a solid tergite on which is developed a complex pattern of ridges and furrows. All other segments are freely articulated. The axial furrow system of segments 2-5 on the second specimen is also complex. The telson is styliform. Although clearly pseudoniscine in character, the large overall size, the proportionally large size and rounded posterior outline of the opisthosoma, and the complexities of the furrows of the axis and on segments 6 and 7, readily differentiate this genus from Pseudoniscus and other related genera. Recently regarded as incertae sedis within the Merostomata (Eldredge, 1974), we now consider Cyamocephalus a valid genus, in some respects the most specialized (derived) member of the family Pseudoniscidae (sensu Eldredge, 1974)"--P. 3. en_US
dc.format.extent 6534406 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York, N.Y. : American Museum of Natural History en_US
dc.relation.ispartofseries American Museum novitates ; no. 2557 en_US
dc.subject.lcc QL1 .A436 no.2557, 1974 en_US
dc.subject.lcsh Cyamocephalus. en_US
dc.subject.lcsh Arthropoda, Fossil -- Great Britain. en_US
dc.subject.lcsh Paleontology -- Silurian -- Great Britain. en_US
dc.subject.lcsh Paleontology -- Great Britain. en_US
dc.title Revision of the pseudoniscine merostome genus Cyamocephalus Currie. American Museum novitates ; no. 2557 en_US
dc.type text en_US

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  • American Museum Novitates
    Novitates (Latin for "new acquaintances"), published continuously and numbered consecutively since 1921, are short papers that contain descriptions of new forms and reports in zoology, paleontology, and geology. New numbers are published at irregular intervals.

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