Reassessment of the index fossils at the Paleozoic–Mesozoic boundary

Yin Hong-fu

pp. 153-171, in English

Abstract:

Based on detailed discussion of respective merits and shortcomings, Hindeodus parvus is suggested as the index fossil for basal Triassic, hence the base of H. parvus Zone as the erathem boundary, and Otoceras as potential index fossil. It is suggested to seek for possible combination of these two taxa as indices for Permian–Triassic boundary after detailed biostratigraphic and phylogenetic researched at species level for Otoceras. An alternative, but less favored, choice is to take Isarcicella isarcica-Ophiceras-Claraia assemblage as the index fossils, i.e., to take the Lower–Upper Griesbachian boundary as the erathem boundary.

Six subdivisions are established for detailed boundary correlation of major sections in Tethys and marginal Gondwana regions. This paper suggests delineation of the Permian–Triassic boundary between subdivisions 4 and 5 of Table 2, that is, at the base of H. parvus Zone. The requirement of non-overlapping stratigraphic column means that it is preferable to select of global stratotype sections in same biogeographic region, preferable in Tethys. The most suitable boundary section seems located in South China, for example Meishan of Changxing County. The Permian–Triassic boundary provides excellent combination of biostratigraphic, chemostratigraphic and eventostratigraphic criteria necessary for its delineation.

Keywords: Permian–Triassic boundary, Hindeodus parvus, Otoceras, six subdivisions of the boundary beds, Meishan section