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A trepostome bryozoan from the Lower Arenig of south Wales: implications of the oldest described bryozoan

Published online by Cambridge University Press:  01 May 2009

Paul D. Taylor  and
John C. W. Cope
Paul D. Taylor
Affiliation:
Department of Palaeontology, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K.
John C. W. Cope
Affiliation:
Department of Geology, University College, Singleton Park, Swansea SA2 8PP, U.K.
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Abstract

A specimen of the trepostome bryozoan Orbipora from the Lower Arenig of south Wales is described and figured. This is currently the oldest unequivocal bryozoan recorded in the literature. Although mostly decalcified, the colony preserves clear remnants of the large styles which characteristically indent the zooecial apertures in Orbipora. The wide palaeogeographical distribution of Orbipora in the early Ordovician is consistent with the hypothesized planktotrophic larval phase. Theoretical considerations and evidence from the occurrence of Orbipora in south Wales suggest that nearshore clastic environments would be fruitful settings in which to search for further early bryozoans, although quality of preservation may be poorer than in offshore carbonates.

Type
Articles
Information
Geological Magazine , Volume 124 , Issue 4 , July 1987 , pp. 367 - 371
Copyright
Copyright © Cambridge University Press 1987

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