Stage Change of Middle-Late Devonian Calcified Algae and Cyanobacteria in South China and Its Significance

摘要

INTRODUCTION The prominence of calcified microbes in the immediate aftermaths of some Phanerozoic mass extinctions suggests that they flourished when metazoans were temporarily reduced (Schubert and Bottjer, 1992). This view has found support in studies of end-Permian (Kershaw et al., 1999), endOrdovician (Sheehan and Harris, 2004), and endDevonian (Riding, 2006; Stephens and Sumner, 2003) extinctions. A complicating factor is that, although microbial carbonates may be common after extinction events, they are often not scarce immediately prior to them. This raises the question whether calcified microbes increased in absolute abundance following metazoan extinctions, or were made more conspicuous through their survival as other groups declined. Evaluation of these possibilities requires detailed study of microbial carbonate abundance both before and after mass extinction.