The Early Palaeozoic was a critical interval in the evolution of marine life on our planet. Through a window of some 120 million years, the Cambrian Explosion, Great Ordovician Biodiversification Event, End Ordovician Extinction and the subsequent Silurian Recovery established a steep trajectory of increasing marine biodiversity that started in the Late Proterozoic and continued into the Devonian. Biogeography is a key property of virtually all organisms; their distributional ranges, mapped out on a mosaic of changing palaeogeography, have played important roles in modulating the diversity and evolution of marine life. This Memoir first introduces the content, some of the concepts involved in describing and interpreting palaeobiogeography, and the changing Early Palaeozoic geography is illustrated through a series of time slices. The subsequent 26 chapters, compiled by some 130 authors from over 20 countries, describe and analyse distributional and in many cases diversity data for all the major biotic groups plotted on current palaeogeographic maps. Nearly a quarter of a century after the publication of the ‘Green Book’ (Geological Society, London, Memoir12, edited by McKerrow and Scotese), improved stratigraphic and taxonomic data together with more accurate, digitized palaeogeographic maps, have confirmed the central role of palaeobiogeography in understanding the evolution of Early Palaeozoic ecosystems and their biotas.
Two of the greatest evolutionary events in the history of life on Earth occurred during Early Paleozoic time. The first was the Cambrian explosion of skeletonized marine animals about 540 million years ago. The second was the "Great Ordovician Biodiversification Event," which is the focus of this book. During the 46-million-year Ordovician Period (489–443 m.y.), a bewildering array of adaptive radiations of "Paleozoic- and Modern-type" biotas appeared in marine habitats, the first animals (arthropods) walked on land, and the first non-vascular bryophyte-like plants (based on their cryptospore record) colonized terrestrial areas with damp environments. This book represents a compilation by a large team of Ordovician specialists from around the world, who have enthusiastically cooperated to produce this first globally orientated, internationally sponsored IGCP (International Geological Correlation Program) project on Ordovician biotas. The major part is an assembly of genus- and species-level diversity data for the many Ordovician fossil groups. The book also presents an evaluation of how each group diversified through Ordovician time, with assessments of patterns of change and rates of origination and extinction. As such, it will become the standard work and data source for biotic studies on the Ordovician Period.
In this book, contributors from diverse backgrounds take a first step toward an integrated view of reefs and the significance of their recent decline. More than any other earth system, coral reefs sit at a disciplinary crossroads. Most recently, they have reached another crossroads - fundamental changes in their bio-physical structure greater than those of previous centuries or even millennia. Effective strategies to mitigate recent trends will require an approach that embraces the myriad perspectives from across the scientific landscape, but will also need a mechanism to transform scientific understanding into social will and political implementation.
From the Preface: The chapters of this book contain contributions from an international group of specialists. They address some important themes in both modern and ancient reef systems. Some chapters contain `snapshots' of reefs of particular intervals, while others touch on relevant themes of both modern and ancient reefs - themes that weave their way through reefs of all ages. This book opens and sets the stage with an introduction to both modern and ancient reefs and reef ecosystems. This chapter is also intended as a basic introduction for students, general geologists, and professionals or others who may be unfamiliar with reefs and reef ecosystems. The chapter addresses the living coral reef ecosystem, stressing among other relevant factors, the importance of ecological and physical interactions between the organisms and their environment. The chapter also addresses mass extinction and provides a general overview of the history of reefs.