Dynamics of the middle-rank taxonomic diversity structure of brachiopods: a quantitative assessment of the Phanerozoic fossil record

Abstract

Ruban, D.A., September 2012. Dynamics of the middle-rank taxonomic diversity structure of brachiopods: a quantitative assessment of the Phanerozoic fossil record. Alcheringa 36, 413–426. ISSN 0311-5518.

Taxonomic diversity structure indicates how higher-rank taxa influence the diversity of lower-rank taxa. Brachiopods experienced significant changes in the superfamily–family, superfamily–genus and family–genus components of diversity structure during the Phanerozoic. The most intense changes occurred at the Cambrian–Ordovician, Devonian–Carboniferous and Permian–Triassic transitions, when new higher-rank taxa began to determine the diversity at lower taxonomic levels. In contrast, the similarity of successive brachiopod assemblages was relatively high during the Ordovician–Devonian, Carboniferous–Permian, Triassic–Cretaceous and Paleogene–Quaternary intervals indicating a form of evolutionary stagnation. High dissimilarity between older and younger assemblages was established at the Cambrian–Ordovician and Permian–Triassic transitions, which mark the distinctions between the Cambrian, Palaeozoic and Modern evolutionary faunas within the target fossil group, i.e., brachiopods. Changes in superfamily–family, superfamily–genus and family–genus components of diversity structure were similar. All ‘Big Five’ mass extinctions left a more or less significant imprint in the dynamics of the diversity structure of brachiopods, but the Late Devonian and end-Permian catastrophes were especially important. Results of the present study may be refined with future improvements to brachiopod suprageneric systematics.

Key words:

• brachiopods
• diversity
• evolution
• punctuated equilibrium
• faunal turnover
• mass extinction
• Phanerozoic

Acknowledgements

The author gratefully thanks the editor S. McLoughlin (Sweden) and two anonymous reviewers for their useful suggestions and criticisms, K.B. Oheim (USA), for her improvements to the text, N.M.M. Janssen (Netherlands), W. Riegraf (Germany) and A.J. van Loon (Netherlands/Poland), for their enthusiastic help with literature, and Ph. Novack-Gottshall (USA), who turned the author's attention to the alternative techniques of similarity measurement.