Patterns and paleoenvironmental implications of end-Permian extinction of Rugosa in South China

Abstract

Late Permian rugose corals are undoubtedly the last phylogenetic representatives of the Rugosa. These corals are widely, though sporadically, distributed, notably in South China. The Late Permian corals of South China decrease markedly in diversity and are represented by surviving genera from the Maokouan, showing common patterns of disappearance, morphologically and phylogenetically. Colonial Wentzelellinae mostly disappeared by the end of the Maokouan, followed by solitary Wentzelellinae and later Waagenophyllinae having simple morphologies. Non-dissepimented solitary corals and fasciculate Waagenophyllinae, though morphologically simple, are common during the Late Permian, ranging up to the latest Permian. Permian Rugosa apparently show two terminal patterns, suggesting environmental differences. One pattern is terminated with a progressive reduction, leaving only non-dissepimented solitary corals as survivors, and the other pattern is distinguished by the disappearance of the platform-dwelling colonial corals at the end of the Permian. The general trend, characterized by later disappearance of the simpler corals, reflects progressively adverse changes in the marine environment. The persistence and disappearance of a latest Permian Waagenophyllum fauna suggests that the regional continuation of favorable environments followed by the onset of and abrupt severe, though temporary, environmentalchanges for coral growth. The causes of rugosan extinction are not necessarily attributed to factors characteristics of the latest Permian time, and the extinction was individually stepwise, each different event disappearance correlating with, and possiblycaused by variable factors, such as sea-level fluctuations and volcanic activity. Multiple interactions of individual factors on a local and global scale affected each faunal component, resulting in selection of corals that culminates in the regional, and finally global, disappearance of Rugosa.