DYNAMIC PATTERNS OF LATEST PROTEROZOIC-PALAEOZOIC-EARLY MESOZOIC MARINE BIODIVERSITY IN SOUTH CHINA

Abstract

Analyses of global biodiversity curves have been important for the interpretation of co-evolution between organisms and environments through geological time. Global curves can be better understood if all the data collected from a multitude of palaeocontinents are analysed and explained separately. South China is a major block possessing more advantages for regional research than any of the other blocks in China. There exists a well-developed succession of marine strata from the Ediacaran through to the Triassic with a relatively high resolution of bio- and chrono-stratigraphy and an extensive marine fossil record. Stratigraphic occurrences of 5685 genera and 1386 families within 32 phyla or subphyla plus groups with uncertain affinities from this interval have been compiled by a large team of palaeontologists. With the exception of the Ediacaran, 50 time intervals with an average duration of 6.8 Ma are investigated. Diversity curves constructed at the levels of genus, family and order indicate that marine biodiversity peaked six times within the intervals: (1) Early Cambrian explosive radiation, (2) Early-Mid Ordovician radiation mainly of the Paleozoic Evolutionary Fauna, (3) Early Silurian radiation, (4) late Early-Mid Devonian radiation, (5) Mid-Late Permian radiation and (6) Mid Triassic radiation chiefly of the Modern Evolutionary Fauna. Drops in biodiversity are controlled by various factors: (1) global catastrophes, which produced rapid losses of biodiversity during short time intervals; (2) global environmental perturbations with long term effects, as in the Carboniferous; (3) regional tectonics and palaeogeographical constraints, resulting in a lack of marine sedimentary rocks in many areas with biodiversity declining, as in the Wenlock; (4) unique sedimentary facies in large areas resulting in biodiversity losses, as in the Late Cambrian and (5) artifactual constraints associated with a lack of fossil record or low research intensity for some intervals, as in the period of about 30 Ma following the Early Cambrian explosive radiation.