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Paedomorphosis and cryptogenesis in trilobites

Published online by Cambridge University Press:  01 May 2009

H. B. Whittington
H. B. Whittington
Affiliation:
Sedgwick Museum, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ
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Summary

Stubblefield suggested that proparian trilobites may have arisen by paedomorphosis. Examples of the role of paedomorphosis in the evolution of species and of particular organs are reviewed. The cryptogenetic renewal of trilobites after the Cambrian resulted in distinctive major taxa, but their relationships to each other and to older groups remain unsolved. Similarities between early developmental stages should be re-assessed as a possible guide to relationships. The early Upper Cambrian, type species of the proparian Schmalenseeia is re-described. It was small, possibly world-wide in distribution, the exoskeleton thin, the parts not articulated, apparently forming a more or less rigid shield. It may have been a paedomorphic, planktic species, but its origin and relationships are obscure.

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Geological Magazine , Volume 118 , Issue 6 , November 1981, pp. 591 - 602
Copyright
Copyright © Cambridge University Press 1981

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