Ecology, biofacies, biogeography and systematics of micromorphic lingulate brachiopods from the Ordovician (Darriwilian–Sandbian) of south-central China

摘要: Ordovician (Darriwilian to Sandbian) micromorphic linguliform lingulate brachiopods are described from the Guniutan Formation at Fenxiang section in Hubei province, and Maocaopu Cili sections Hunan province of south-central China, situated on Yangtze Platform. A total 7560 specimens 155 limestone samples (within interval Lenodus variabilis – Pygodus anserinus biozones) assigned 22 species, representing a low taxonomic diversity abundance fauna. The fauna is dominated by Acrotretoidea, mainly species Torynelasmatidae, with Torynelasma most abundant (more than 40% number specimens), along Eoconulidae Eoconulus (18% total) second common forms. Species Ephippelasmatidae also (16% diverse, include representatives Myotreta Numericoma, as well Ephippelasma, whereas Scaphelasmatidae somewhat less (13% total). All three investigated represent outer shelf environments, but relatively deeper position, proximity south-eastern margin Upper Platform, close its boundary Jiangnan Slope. quantitative analysis relative data was carried out order investigate biofacies distribution brachiopod communities across something that has not been attempted before Palaeozoic linguliforms. Six microbrachiopod could be recognized sections. major shift, which occurred upper part Microzarkodina ozarkodella Zone, time onset initial rise Mid Darriwilian Carbon Isotope Excursion (MDICE) suggests these may have depth controlled.