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Morphological and microstructural evidence for the origin and early evolution of Ecphora (Mollusca: Gastropoda)

Published online by Cambridge University Press:  14 July 2015

Joseph G. Carter
Affiliation:
Department of Geology, The University of North Carolina at Chapel Hill, Chapel Hill 27599-3315
Thomas J. Rossbach
Affiliation:
Department of Geology, The University of North Carolina at Chapel Hill, Chapel Hill 27599-3315
Keith J. Robertson
Affiliation:
Department of Geology, The University of North Carolina at Chapel Hill, Chapel Hill 27599-3315
Lauck W. Ward
Affiliation:
Virginia Museum of Natural History, 1001 Douglas Avenue, Martinsville 24112

Extract

Ecphora is one of the most easily recognized gastropod genera in late Oligocene, Miocene, and Pliocene marine formations in the southeastern United States. Its generally large size, strong spiral ribs, and brown, calcitic exterior are much prized by fossil collectors. However, despite speculations by Petuch (1988), its evolutionary origins have remained obscure. The present shell microstructural and mineralogical evidence suggests that the earliest ecphoras were entirely aragonitic and that the thick calcitic outer layer of the later Miocene and Pliocene species originated as a thin calcitic crust on the crests of the ribs of a latest Oligocene or earliest Miocene species.

Type
Paleontological Notes
Copyright
Copyright © The Paleontological Society 

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