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WEBBY, B. D., PARIS, F., DROSER, M. L. & PERCIVAL, I. G. 2004. The Great Ordovician Biodiversification Event. xi+484 pp. New York: Columbia University Press. Price US $99.50, £69.00 (hard covers). ISBN 0 231 12678 6

The starting point of this great compilation is Sepkoski’s fertile idea that most life-forms can be assigned to one of three ‘evolutionary faunas’, the Cambrian, the Palaeozoic and the Modern faunas. The Palaeozoic Evolutionary Fauna largely originated in the Ordovician Period and was much depleted by the end-Permian mass extinction, after which the Modern Fauna dominated. In order to get a better understanding of the Palaeozoic faunal origination, a project on the Ordovician Biodiversification Event (supported by the International Geological Correlation Programme) was initiated around 1998 and a group of a hundred specialists, representing expertise on practically all the faunal and floral groups of fossils, was invited to compile information on the development of the Ordovician biota. Considering the size and complexity of the project, and the completeness of the end result, the editors and authors have done well to get the present volume to press in good time. As the present book makes abundantly clear, the Ordovician was a hugely important period; marine life everywhere underwent a great diversification and gave rise to many forms of life whose descendants are with us today, but, just before the advent of the Silurian …