Palaeoecology of the conodonts Hindeodus and Clarkina during the Permian-Triassic transitional period

Detailed investigation of the distributions of the Hindeodus and Clarkina ( Neogondolella) conodont faunas has been undertaken on the P/T boundary stra ta of the Meishan section, Zhejiang Province, South China, in association w ith detailed facies analysis. This reveals that Hindeodus increased and Cla rkina sharply declined in abundance during a phase of relative sea-level ri se which began at the end-Permian (Bed 25) and extended into Early Triassic . This was associated with the development of anoxic conditions. This distr ibution does not accord with previous suggestions that Hindeodus was a near shore, shallow water taxon. The decline of the supposed deeper water genus Clarkina is also somewhat surprising but it may relate to the inhibition of a nektobenthic genus by dysoxic-anoxic bottom waters. The widespread facie s and geographic distribution of Hindeodus suggests it was a pelagic type u naffected by anoxic bottom waters. Hence, the Hindeodus lineage provides a reliable criterion for identification of the Permian-Triassic boundary. (C) 2001 Elsevier Science B.V. All rights: reserved.