Chapter 1 Early Palaeozoic biogeography and palaeogeography: towards a modern synthesis

McKerrow (1990), the so-called ‘Green Book’, marked a turn-ing point in Palaeozoic biogeography and geography. The 40 papers in that volume included substantial new data and important syntheses on palaeoclimatology, palaeomagnetism and the distri-bution of climatically sensitive sediments, but the majority of con-tributions were on Palaeozoic biogeography. Since 1990 there have been major advances in the taxonomy of Early Palaeozoic organisms, the correlation of Lower Palaeozoic rocks together with numerical methods for the analysis of fossils and their distri-butions. Moreover and most significantly there has been a quantum leap in the accuracy and precision of palaeogeographic reconstruc-tions, reconciling in many cases palaeomagnetic data and the dis-tribution of fossil organisms. The Early or (Lower) Palaeozoic was an interval character-ized by a major radiation of marine life, including not only the ‘Cambrian Explosion’, but also the ‘Great Ordovician Biodiver-sification’. An International Geoscience Programme (formerly International Geological Correlation Programme, IGCP) was dedi-cated to the Great Ordovician Biodiversification Event (IGCP 410, 1997–2002). This programme focused on the Ordovician, but it also analysed the roots of the Ordovician biodiversifica-tion in the Cambrian, the first big mass extinction at the end of the Ordovician, and the Silurian recovery. A subsequent programme, the IGCP 503, ‘Ordovician Palaeogeography and Palaeocli-mate’, followed from 2004 to 2009. Several special issues and review papers resulted from this programme, including special issues on Lower Palaeozoic palaeoenvironments (Servais & Owen