Coral biogeography in the Late Ordovician (Cincinnatian) of Laurentia
Robert J. Elias, Graham A. Young, Dong-Jin Lee, Boo-Young Bae, 2013. "Coral biogeography in the Late Ordovician (Cincinnatian) of Laurentia", Early Palaeozoic Biogeography and Palaeogeography, D. A. T. Harper, T. Servais
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During the Late Ordovician, Cincinnatian, the epicontinental seas and continental margin of Laurentia provided habitats that were suitable for corals. Biogeographical differentiation occurred within this equatorially placed continent, when corals were introduced to areas that had fundamentally different environments. There were four biogeographical divisions, characterized by distinctive faunas that included some endemic taxa: the Red River–Stony Mountain Province, Richmond Province, Edgewood Province and the less well understood, informal ‘Continental Margin’ Area. In each division, the potential for diversification and the capacity for diversity were determined by factors such as the duration and size of the division, the amount of immigration, the extent of evolution and biogeographical differentiation, faunal responses to changes in sea-level and climate, and the complexity of the ecological structure. The development of multiple biogeographical divisions, each contributing to overall diversity, enhanced the ‘Great Ordovician Biodiversification Event’. During the latest Ordovician mass extinction, there was a reduction of diversity and loss of biogeographical divisions within Laurentia. The divisions were terminated when their characteristic taxa disappeared, in response to major environmental changes associated with glaciation in Gondwana and subsequent global warming.
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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, Memoir 12, 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.