Prof. XIE Shucheng, a young scientist with China University of Geosciences, and YIN Hongfu, an academician of the Chinese Academy of Sciences, in collaboration with UK scientists, revealed microbial changes coupled with faunal mass extinction. Built on the study of microbial community changes across the Permo/Triassic (P/Tr) boundary at Meishan in South China, the finding was published in Vol. 434 of the journal Nature.

XIE and his collaborators, using organic chemical means, including petrographic examination, analyzed the fossilized molecules near the Permo/Triassic boundary, and screened out organic molecules of noticeable biological significance. The study reveals that the boundary has seen at least twice drastic changes of blue bacteria. To further understand the relationship between changes of blue bacteria and invertebrate mass extinction, XIE and others calculated out the extinction rate of invertebrates at specific layers, corresponding to the stratigraphic distributions of fossilized animal species near the boundary. Calculation results show that the peak of faunal mass extinction is well coupled with the 2-methylhopane (2-MHP) index, a ration reflecting the changes of blue bacteria, indicating microbial and faunal response to catastrophic events. Such events caused the extinction and initiated ecosystem changes.

XIE and his collaborators?¯ understanding of the high definition 2-methylhopane index and associated marine invertebrate extinction provides evidence for at least two episodes of biotic crisis across the P/Tr boundary.