Conodont succession from the new GSSP section of the basal Lopingian(Upper Permian)
The original Global Stratotype Section and Point(GSSP)for the base boundary of the Lopingian Stage(Permian)was defined at the Penglaitan section in Laibin of Guangxi,South China.Unfortunately,this section has been permanently submerged due to the construction of a hydroelectric dam.Recently,a new GSSP for the Lopingian base,defined by the first appearance datum(FAD)of the conodont Clarkina postbitteri within the lineage J inogondolella granti Clarkina postbitteri→C.dukouensis at the new Penglaitan section,which is nearby the original Penglaitan section,has been formally ratified by the International Commission on Stratigraphy(ICS)of the International Union of Geological Sciences(IUGS).This paper presents in detail the conodont biostratigraphy from the new Penglaitan section.Based on high-resolution conodont sampling,at least seven species belonging to five genera have been identified from the uppermost part of the Maokou Formation to the base of the Heshan Formation.These include Clarkina dukouensis,C.postbitteri,Hindeodus sp.,Iranognathus sp.,Jinogondolella granti,J.xuanhanensis,and Sweetognathus fengshanensis.The taxonomy and lineage of key species within the Clarkina to Jinogondolella transition are discussed,confirming that Jinogondolella granti is the direct ancestor of Clarkina postbitteri.Four conodont zones,in ascending order,are recognized in this section:the Jinogondolella xuanhanensis Zone,the J.granti Zone,the Clarkina postbitteri Zone,and the C.dukouensis Zone.The FAD of the index conodont species C.postbitteri occurs at the base of Bed n6L,which has been redefined as the base-Lopingian GSSP.
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