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Some molluscan problematica from the Upper Cambrian–Lower Ordovician of the Ozark uplift

Published online by Cambridge University Press:  14 July 2015

Bruce L. Stinchcomb  and
Guy Darrough
Bruce L. Stinchcomb
Affiliation:
St. Louis Community College at Florissant Valley, St. Louis, Missouri 63135
Guy Darrough
Affiliation:
47 Pomme Ave., Arnold, Missouri 63010
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Abstract

The mollusk Hemithecella, which occurs abundantly both above and below the Cambrian-Ordovician boundary in the Ozark region of Missouri, is discussed and compared with Matthevia and with the polyplacophoran order Paleoloricata and found to be distinctly different. Based upon the presence of monoplacophoran-like multiple muscle scars and asymmetrical valves, Hemithecella and related forms described here are considered to be molluscan problematica. Hemithecellids are mollusks; however, their affinity to other classes is unclear although structural similarities to the Monoplacophora are noted. The new order Hemithecellitina is proposed. It contains two new families, the Hemithecellidae and the Robustidae. Three new genera, Conodia, Robustum, and Elongata, and nine new species are proposed: Conodia levicosta, C. acuminata, Robustum nodum, R. phallarium, Elongata perplexa, Hemithecella elongata, H. abrupta, H. quinquelites, and H. eminensis.

Type
Research Article
Information
Journal of Paleontology , Volume 69 , Issue 1 , January 1995 , pp. 52 - 65
Copyright
Copyright © The Paleontological Society 

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