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Biometry of the Late Cambrian trilobite genus Dikelocephalus and its implications for trilobite systematics

Published online by Cambridge University Press:  20 May 2016

Conrad C. Labandeira
Affiliation:
Smithsonian Institution, Department of Paleobiology, Natural History Building, MRC-121, Washington, D.C. 20560
Nigel C. Hughes
Affiliation:
Cincinnati Museum of Natural History, 1720 Gilbert Avenue, Cincinnati, Ohio 45202

Abstract

It has been proposed previously that the northern Mississippi Valley Sunwaptan trilobite genus Dikelocephalus comprises 26 species. Morphometric analyses demonstrate that many of the criteria that had been used to define species of Dikelocephalus are invalid and additional analysis of biostratigraphically and biogeographically constrained collections is necessary before the taxonomic status of Dikelocephalus can be fully resolved. Our results indicate that infrageneric morphological variation in Dikelocephalus is continuous and lacks gaps that could be the basis for establishing multiple species. Many of the characters shown to be taxonomically insignificant in Dikelocephalus are also widely used in the definition of other trilobite taxa. This suggests that the species-level taxonomy of many trilobites may be substantially oversplit. Recognition of widespread oversplitting will have important consequences for biostratigraphic zonations, paleogeographic distributions, and estimates of taxonomic diversity.

Type
Research Article
Copyright
Copyright © The Paleontological Society 

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