中国科学院南京地质古生物研究所机构知识库

The Wangehengpo Frasnian section of Dushan County contains two atrypid brachiopod assemblages. The lower is characterized by the Atryparia (Costatrypa) dushanensis fauna that appears at the base of the Hejiazhai Member approximately in the falsiovalis to transitans conodont zones; the upper is characterized by the Radiatrypa yangi fauna. which appears in the Lujiazhai Member approximately correspondent with the hassi to Upper rhenana conodont zones. Atrypid brachiopods, together with other brachiopods from the Dushan section show that the Hejiazhai Member is of Frasnian age. Preliminary analyses of Frasnian atrypid brachiopods from sections of South China indicate that there are nine genera and subgencra including Attyparia (Costatiypa), Kyrtatrypa, Spinatrypa, Isospinatrypa, Spinattypina, Iowatrypa, Desquamatia (Desquamatia), Desquamatia (Seratrypa), and Radiatrypa. Atrypid species diversity did not change much through the Frasnian. On a regional scale in South China, most atrypid species went extinct prior to the Frasnian/Famennian boundary. At any specific locality or section, these atrypids became extinct about 20-40 m below the Frasnian/Famennian (F/F) boundary, within the linguiformis conodont Zone, marking this as the major extinction level. Three new atrypid species are described: Atryparia (Costatrypa) dushanensis, Iowatrypa pseticlobodini, and Radiatrypa yangi.