Radiolarian evolution during the latest Permian in South China

Investigations on the Upper Changhsingian radiolarian fauna in South China allow us to trace, in detail, extinction processes and to research relations between the Permian and Triassic radiolarian faunas. Evolution of the radiolarian fauna is divided into three stages: radiation, extinction and survival intervals. In the radiation interval (10.28–2.68 m below the PTB), the radiolarian fauna consists of 137 species belonging to 50 genera and includes 8 representative Triassic genera. Two crises are recognized in the extinction interval (2.68–0.77 m below the PTB). The first crisis is characterized by extinction at species level and the second crisis, by disappearance of many genera. In the survival interval (0.77 m below the PTB to lower Lower Triassic), the radiolarian fauna includes only Paleozoic-type taxa and its diversity and abundance are unusually low. The first crisis corresponds to the extinction located at the top of Bed 24d in Meishan Section D and the second crisis, to the extinction located at the top of Bed 24e of Meishan Section D.