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Skeletal Overgrowths Among Epizoans from the Silurian (Wenlockian) Waldron Shale

Published online by Cambridge University Press:  08 February 2016

W. David Liddell
Affiliation:
Department of Earth Sciences, University of New Orleans, Lake Front, New Orleans, Louisiana 70148
Carlton E. Brett
Affiliation:
Department of Geological Sciences, University of Rochester, Rochester, New York 14627

Abstract

Substrata for numerous epizoans in the Silurian Waldron Shale were provided by the toppled and overturned calyces of camerate crinoids. These were inhabited by a skeletonized fauna consisting of at least 25 species; including several bryozoans, tabulates, inarticulate brachiopods, worms, and echinoderms.

Many of the encrusting bryozoans exhibit skeletal overgrowths which appear to reflect competitive interactions for space. Coexistence of certain of the bryozoans involved in such interactions is suggested by skeletal features such as inflated growth forms and upturned margins at junctions between colonies (both representing attempts to avoid being overgrown). In addition, the occurrence of overgrowth reversals within individual encounters indicates contemporaneity of that pair. Species may be ranked according to their relative overgrowth success; however, this ranking is far from rigid as lower ranked species may on occasion overgrow more highly ranked species. Such nontransitive patterns appear similar to those described from Recent cryptic bryozoan faunas.

Type
Articles
Copyright
Copyright © The Paleontological Society 

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