Comparison of Modern Biodiversity Variation with Paleozoic-Mesozoic Biotic Crisis

Since the 18th century the earth environment was extremely destroyed by anthropogenic activity, associated with the sharp decrease of biodiversity. In order to understand the trend of biodiversity variation, authors compare the biodiversity variation within recent 400 years with the biotic crisis occurring at the transitional period of Paleozoic-Mesozoic. Current biodiversity, evaluated by means of 'statistic of extinction species' and 'species-area curve', is characterized by a high species extinction rate ranging from 8×10⁴ species to 1.2×10⁶ species per million year, but nearly by zero of genus extinction. Similarly, the initial phase of the Paleozoic-Mesozoic mass extinction, calculated from the previously reported fossil records, was also distinguishable by a high species extinction rate ranging from 40 to 150 species per million year and a low extinction rate of genus, 66 genera per million year, which is far less than 465 genera per million year representative of the peak phase of Permian-Triassic mass extinction. Modern biodiversity variation is thus comparable with the initial phase of the Permian-Triassic mass extinction.