Two episodes of foraminiferal extinction near the Permian–Triassic boundary at the Meishan section, South China

Abstract

Stratigraphic distributions of foraminifer species from the Permian–Triassic (P/Tr) transition of the Meishan section, South China demonstrate two episodes of biotic mass extinction near the P/Tr boundary. The first episode is calibrated to the top of Bed 24 and is indicated by a loss of 49 out of 64 Changhsingian species (77%). The second phase is expressed by the disappearance of 32 out of 34 species (94%) recorded in Beds 25–27 and corresponds to the base of Bed 28. Only Nodosinelloides aequiampla survived into the early Griesbachian and another species, Glomospira regularis, rebounded in the late Griesbachian. The Lagenida and Textulariida lost 71% and 50% of species, respectively, in the first episode of the P/Tr extinction. In the Lagenida, only one taxon temporarily survived over the second crisis but became extinct soon after in Bed 29, while one newcomer occurred in the late Griesbachian. In the Textulariida, one Lazarus species rebounded in the late Griesbachian when two new forms rose. Both the Fusulinida and Miliolida suffered a great loss in the first extinction event, losing about 85% and 89% of the species, respectively. Their temporary survivors were wiped out in the second episode of the P/Tr crisis. The large, architecturally complex taxa suffered the first crisis much more severely than the small, simple tests. Selective extinction and rebound among the forms bearing various test walls probably indicate the different physiological reactions of various foraminifer groups to the defaunation events such as biocalcification crisis, hypercapnia, elevated CO2 content and global warming that prevailed in the aftermath of the P/Tr mass extinction.