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

The benchmark volume edited by Christopher Scotese & Stuart McKerrow (1990), the so-called ‘Green Book’, marked a turning point in Palaeozoic biogeography and geography. The 40 papers in that volume included substantial new data and important syntheses on palaeoclimatology, palaeomagnetism and the distribution of climatically sensitive sediments, but the majority of contributions 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 distributions. Moreover and most significantly there has been a quantum leap in the accuracy and precision of palaeogeographic reconstructions, reconciling in many cases palaeomagnetic data and the distribution of fossil organisms.The Early or (Lower) Palaeozoic was an interval characterized by a major radiation of marine life, including not only the ‘Cambrian Explosion’, but also the ‘Great Ordovician Biodiversification’. An International Geoscience Programme (formerly International Geological Correlation Programme, IGCP) was dedicated 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 biodiversification 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 Palaeoclimate’, followed from 2004 to 2009. Several special issues and review papers resulted from this programme, including special issues on Lower Palaeozoic palaeoenvironments (Servais & Owen 2010) and Lower Palaeozoic sea-level and climate (Munnecke et al. 2010).The papers presented here originated from the ‘Absolutely Final Meeting of IGCP 503: Ordovician Palaeogeography and Palaeoclimate’ in Copenhagen, September, 2009 (see Harper et al. 2011). That symposium focused especially on the palaeogeographical dimension of the Cambrian–Ordovician marine radiation; the current volume critically uses the available world pre-drift maps for the …