You can download Palaeobiogeography and Biodiversity Change ebook here.
- Title: Palaeobiogeography and Biodiversity Change: The Ordovician and Mesozoic-Cenozoic Radiations
- Author: J. A. Crame, Alan W. Owen, J. A. Crame, Alan W. Owen
- Publisher: The Geological Society
- Pages: 213
Biodiversity change is now one of the most important topics of investigation for biogeographer and palaeobiogeographer alike. Demonstrably, great shifts in the numbers of plant and animal taxa are occurring on certain parts of the Earth’s surface at the present day, and much effort is currently being expended to determine why this should be so. Climate change in particular is held by many to be the most likely cause of dramatic range shifts and local extinctions.
With their longer time perspective, palaeontologists are continually surveying the fossil record for signs of global biodiversity change in the past. Much attention has rightly been paid to studying the spectacular mass extinctions during the Phanerozoic, but what happens in between them? Many palaeobiologists now believe that there may have been two pronounced intervals when life radiated (i.e. diversified) spectacularly: the Ordovician Period, and the mid-Mesozoic-Cenozoic eras. These episodes mark the steepest sustained rises on the ‘curve of Life through time’; the intervening Silurian-Jurassic interval is the much flatter plateau, punctuated by mass extinctions and their recovery intervals.
Both the scale of these spectacular diversity increases and their probable causes are currently topics of intense debate. To the geologist, there is an intriguing link here between dispersed continents (as opposed to the presence of supercontinents), changing climates (both intervals ended with widespread glaciations), and the proliferation of life. We now know that the accumulation of Life on Earth is extremely complex; it is not just a matter of packing more taxa into any one habitat, but also of packing more habitats within a province, more provinces within a region, and more regions within the biosphere. Were the Ordovican and mid-Mesozoic-Cenozoic two intervals of time when there was a fundamental reorganization of biodiversity on a hierarchy of biogeographical scales?