Early Ordovician conodonts from Zhejiang Province, southeast China and their biostratigraphic and palaeobiogeographic implications

Abstract

Forty-two conodont species are documented from the Liuxia, Shijiatou and Jingshan formations in Zhejiang Province of southeast China, located palaeogeographically on the Jiangnan Slope offshore to the Yangtze Platform. From these faunas, eight successive conodont biozones of Tremadocian to middle Floian (Early Ordovician) age are recognized, including the Cordylodus lindstromi Biozone, Cordylodus angulatus Biozone, Chosonodina herfurthi Biozone, Paltodus deltifer Biozone, Paroistodus proteus Biozone, Triangulodus bifidus Biozone, Serratognathus diversus Biozone and Prioniodus elegans Biozone. Several zonal index species of the Baltoscandian succession—Paltodus deltifer, Paroistodus proteus and Prioniodus elegans—are described and illustrated in detail for the first time from South China. Co-occurrence of P. proteus and Serratognathus bilobatus in several samples below the appearance of P. elegans also confirms correlation of the S. diversus Biozone (basal Floian) with the upper P. proteus Zone of the Baltoscandian succession. These Zhejiang faunas are dominated by pandemic forms, and are similar to those of the Open-Sea Realm elsewhere, inhabiting deep, offshore environments.