Mixed continental-marine biotas following the Permian-Triassic mass extinction in South and North China

Correlation between marine and continental Permian-Triassic (P-Tr) strata is crucial for full understanding of the nature of this global extinction event, but it has proved difficult to achieve. Here, we show that two sections in South China and North China record similar mixed continental-marine biota in the post-extinction stratigraphic interval, including conchostracans, plants, insects, marine bivalves and lingulid brachiopods. In addition, the continental P-Tr mass extinction was represented by a sharp decrease in the diversity and abundance of the Gigantopteris flora in South China, but eliminated the Palaeozoic-type conifer flora and herbivorous pareiasaurs in North China. These mixed continental-marine biota provide the biological evidence for stratigraphic correlation between marine and continental P-Tr transitional beds in South China and North China, especially the co-occurrence of the Pteria-Towapteria-Eumorphotis bivalve assemblage and the Euestheria gutta-bearing conchostracan fauna or Euestheria gutta-Magniestheria mangaliensis-Palaeolimnadiopsis vilujensis conchostracan assemblage. We propose that these specific marine bivalve and continental conchostracan assemblages could be considered as markers of P-Tr transitional beds in marine-continental siliciclastic settings.