Early-Mid Ordovician brachiopod diversification in South China

查看全文 作　　者：ZHAN Renbin, RONG Jiayu, CHENG Jinhui & CHEN Pengfei Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences;State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing 210008, China 出　　处：《Science China Earth Sciences》索引2005年第48卷第5期,共14页 基　　金：supported by MST(GrantNos.G2000077700 and DEA20020-4);NSF Grant No.40472 002);CAS(Gramt No.KZCX2-SW-129)of China 摘　　要：Affected by paleogeographic position, paleoclimatic condition and depositional environments, the increase of the Early-Mid Ordovician brachiopod diversity of South China commenced at the beginning of the Ordovician (early Tremadoc), accelerated from the Tetra- graptus approximatus Biozone (base of Arenig), and reached its first acme in the Didymograptus eobifidus Biozone (mid early Arenig) when the number of brachiopod genera was over 7 times as great as that at the start of the Ordovician. This was the first radiation in the history of brachiopod macroevolution in South China, which occurred nearly 5 graptolitic biozones earlier than the global trend of the great Ordovician biodiversification (in the lower part of the Undulograptus austrodentatus Biozone). It is also characterized by (1) the origination or first occurrences of some major groups, such as the punctate dalmanelloids and the pseudopunctate stro- phomenoids including Plectambonitoidea (cardinal process simple or absent) and Stro- phomenoidea (cardinal process bilobed) in South China; (2) niche expansion, particularly in the first occupation of deeper water benthic regimes by the Euorthisina-Nocturnellia Association developed at Houping, Chengkou, northern Chongqing; and (3) the differentiation of brachiopod faunas under different environmental conditions. The gradual and increasing separation from Gondwana may have been one of the factors responsible for the radiation in South China. 关 键 词：biodiversity, evolutionary radiation, brachiopods, Early-Mid Ordovician, South China.