Diversity patterns of Carboniferous and Permian rugose corals in South China

Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, ChinaThe diversity and changing patterns of rugose corals in the Carboniferous and Permian of South China are analysed by statis-tical analyses of 45 families, 284 genera, and 1979 species from 14 consecutive time intervals. The ancestors of Carboniferousrugose corals originated early and underwent preliminary radiation in the late Famennian, but were eliminated by the Hang-enberg global regressive event, which marks the Devonian—Carboniferous boundary. Radiation of typical Carboniferousrugose corals began in the late Tournaisian, when they were represented by an abundance of columellate taxa such as Kuei-chouphyllum and a significant diversification of Keyserlingophyllum. A decrease in the diversity of rugose genera occurred inthe Serpukhovian, followed by a change in the composition of the rugose coral assemblages at the Mid-Carboniferous Serpu-khovian—Bashkirian boundary, where large dissepimented taxa with complex axial structures disappeared. In the Bashkirianthe Serpukhovian taxa were replaced by compound rugosan taxa of the Geyerophyllidae, Kepingophyllidae and Waagenophyl-lidae. This compositional change was associated with a global regressive event, recognized in South China by the absence ofupper Serpukhovian strata in many places and by several erosional surfaces in carbonate sequences in the Lower Yangtzeregion.ThisregressiveeventwasprobablycausedbyanepisodeofglaciationinGondwana. SubsequenttransgressionoccurredinSouthChinaduringtheearlyBashkirian,where awide,uniformshallow-water platformdevelopedinSouthChina,on whichwere deposited tidal-flat dolostone and pure limestone containing compound rugose corals. Another change in the rugose coralassemblages, at the Sakmarian-Artinskian boundary, resulted in the absence from the Artinskian of representatives of typicalPennsylvanian and Early Permian families such as the Bothrophyllidae, Lithostrotionidae, Cyathopsidae, and Petalaxidae.FamiliesuniquelytypicalofthePermian,characterized byWaagenophyllidaeandKepingophyllidae,dominatepost-Sakmarianstrata. This faunal change may be related to a major, worldwide regression, recognized at the end of the Sakmarian. Extinctionof rugose corals at the end of the Permian occurred in two phases in South China. The first phase occurred at the end of theCapitanian and eliminated 47% of the families and 45% of the genera. Extrusion of the Omeishan Basalt, which is widelydistributed in the western part of South China, and/or a global regression at the end of the Guadalupian could be the principalcausesofthisfirstphaseofmassextinction.Thesecondphase,whichoccurredattheendoftheChanghsingianandisthelargestextinction event in Earth’s history, eliminated all remaining rugose corals. Copyright # 2006 John Wiley & Sons, Ltd.