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Early Evolutionary History of Diasome Mollusks

Published online by Cambridge University Press:  19 July 2017

John Pojeta Jr.*
Affiliation:
U.S. Geological Survey, Washington, D. C. 20560
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Extract

The subphylum Diasoma (Runnegar and Pojeta, 1974) is a phylogenetic taxon used to show the commonality of origin, ecology, and gross structure of the classes Rostroconchia, Pelecypoda (=Bivalvia), and Scaphopoda. Diasomes have pseudobivalved, bivalved, or univalved shells, which often gape at the anterior and posterior ends. The mouth and anus open at opposite ends of the shell. The head is poorly differentiated or absent, and the radula is present or absent. The stratigraphic range is lowest Cambrian through Holocene.

Type
Research Article
Copyright
Copyright © 1985 University of Tennessee, Knoxville 

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