Brachiopod diversity patterns from Carboniferous to Triassic in South China

Abstract

AbstractIt has long been recognized that the trend of marine diversity from the Carboniferous to the Triassic includes an approximately 100‐myr‐long stable biodiversity stage ranging from the Late Carboniferous to the late Middle Permian, the most severe end‐Permian mass extinction in the Phanerozoic (pre‐Lopingian crisis and end‐Changhsingian mass extinction together), a bleak stage in the Early Triassic and a rapid recovery stage in the Middle Triassic. However, little attention has been paid to smaller diversity fluctuations among relatively stable stages in the Carboniferous and Permian. Here, we establish a database of the brachiopod fossil records from the Carboniferous to Triassic in South China, including 104 families, 373 genera, 2081 species recorded by 7948 occurrences with relatively detailed biostratigraphic controls. Analyses based on the raw taxonomic richness at familial, generic and specific levels, proportional and total extinction/origination/turnover rates, and rarefaction analyses for 21 different intervals from the Carboniferous to Triassic reveal that the brachiopod diversity trends can be generally divided into two distinctly different stages. Brachiopods were highly diversified during the Carboniferous and Permian Periods, whereas they were dramatically reduced in diversity after the end‐Changhsingian mass extinction. Brachiopods were abundant during the Early Carboniferous Tournaisian and Viséan, and were characterized by many genera extending from the Late Devonian. This was followed by a significant simple diversity decline in the Serpukhovian Stage. The Early Permian (either in Sakmarian or Artinskian) diversity decline previously perceived by coral and fusulinid workers is indicated by the raw generic and familial richness, and taxonomic richness per million years. However, it is not expressed by the rarefied brachiopod trajectory, which is probably affected by sampling effect or taxonomic selectivity. Brachiopods apparently declined from Capitanian to Early Wuchiapingian. Thus, the brachiopod diversity trajectory from Pennsylvanian Bashkirian to Late Guadalupian Capitanian generally characterises a long stable stage. Brachiopods are extremely abundant in the Late Wuchiapingian and Changhsingian in view of raw taxonomic richness, but a rarefied trajectory reveals a flat step following the pre‐Lopingian (end‐Guadalupian) crisis until the end‐Changhsingian mass extinction. Therefore, the previously widely perceived Lopingian radiation after the pre‐Lopingian crisis appears to be at least partly over‐stated. Brachiopods experienced a long bleak stage in the Early Triassic, followed by a rapid recovery in the Anisian, and reached their acme in the Norian, but never recovered to such a flourishing degree during the Carboniferous and Permian Periods. Brachiopods were eliminated in South China by the end‐Triassic withdrawal of the sea from this region. Copyright © 2006 John Wiley & Sons, Ltd.