RECENT DEVELOPMENTS AND OUTSTANDING QUESTIONS ABOUT THE END-PERMIAN MASS EXTINCTION (Invited Presentation)

The end-Permian mass extinction has been a topic of intense research, because of its status as the largest Phanerozoic extinction, because of the pivotal role it played in ecological and evolutionary change, and because it shares many parallels with ongoing anthropogenic perturbations. Extensive research over the past decade has clarified many aspects of the crisis. Precise biostratigraphic and radiometric controls have constrained the position and timing of extinction at numerous sections, enabling recognition of a geologically-rapid crisis. The consequences of Siberian Traps flood basalt eruption can explain many of the geological, geochemical, and paleontological observations, as the voluminous CO₂ release would have triggered ocean acidification and global warming, leading to increased weathering and nutrient-driven shallow-marine anoxia and euxinia. However, there are outstanding questions that must be resolved for a deeper understanding of the end-Permian extinction and before it can be used as an analogue for other crises. Despite abundant evidence for anoxia and increasing proxy support for ocean acidification, the precise timing and relative importance of each stressor are not as well-resolved. Because the timing and tempo of extinction have only been quantified at a few sections, the geographic or bathymetric synchroneity is largely unconstrained and the pattern of taxonomic losses is not known at high resolution. Likewise, because much of the research has focused on the immediate extinction interval, the duration of recovery itself or of events such as the chert gap, reef gap, and Lilliput effect are controversial. Closer integration of modeling, geochemical proxies, and the paleobiological pattern of extinction at a wider range of locations will be crucial to resolving these outstanding questions, but a more detailed understanding of the end-Permian extinction could be a key to understanding the present and future.