The Great Ordovician Biodiversification Event

Abstract

Barry D. Webby, Florentin Paris, Mary L. Droser, and Ian G. Percival, eds., 2004, Columbia University Press, New York, 484 p. (Hardcover, US $99.50) ISBN 0231-12678-6. Have you heard the joke about the time a systematist, a taxon-counter, and a paleoecologist walked into a bar? It is not surprising that a significant proportion of paleontological attention is focused on the Cambrian Explosion; it indeed marks the rise to dominance of skeletonized metazoans and the emergence of most phyla. But the Cambrian Radiation is inherently difficult to study: the intricacies involved in reconstructing stem-group phylogenies, the lack of a globally correlated time scale, a dearth of paleomagnetic data, often sparsely fossiliferous strata, and significant regional differences in litho- and biofacies all combine to make it difficult to understand the historical underpinnings of this event, despite recent efforts to the contrary (Zhuravlev and Riding, 2000). In contrast, the ensuing Ordovician is nearly unparalleled in its record. The stratigraphic record is significant and nearly complete over broad cratons, fossiliferous strata are abundant and well preserved, there is now a relatively stable and well-constrained time scale for global correlation, and documentation of isotopic and sea-level trends is improving. The interval, sometimes termed the Ordovician Radiation, also is nearly equal to the Cambrian in terms of its evolutionary and ecological consequences. This period witnessed the appearance of dozens of crown-group representatives of taxonomic classes and orders and the first development of communities that would dominate the remainder of the Paleozoic and even the post-Paleozoic. Despite this significance, and the presence of an active global pool of Ordovician workers, very few works have focused extensively on the Ordovician Radiation. This volume partially fills this lacuna. It acts as a sort of final report for the IGCP 410 project, with the goal of documenting the global, and …