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Causes and Consequences of Mass Extinction

Causes of Mass Extinction graph

Composite carbon isotopic curve for the Changxingian Carnian (Cordevolian) compared to the pattern of biotic recovery from the end-Permian extinction. Lithostratigraphy and conodont ranges are shown for the Upper Guandao section. The conodont ranges are used to constrain the Middle and Late Triassic time scale. Carbon isotope data: red, Guandao; blue, Dajiang; gold, Dawen; green, Upper Guandao. From Payne et al., 2004, Science.

End-Permian mass extinction

One primary focus of current research in the Paleobiology Lab is field-based examination of biological evolution and environmental change associated with the end-Permian extinction and its aftermath. We have used a variety of approaches to attempt to better characterize the cause(s) of mass extinction, to quantify the pattern and timing of extinction and recovery, and to identify connections between biological and environmental change through this important interval of Earth history.

Much of our work on the Permian-Triassic transition uses carbonate platform sediments from China, Turkey, and Japan. We use the carbonate strata as biological, environmental, and geochemical archives. Recent work has been aimed at obtaining a high-resolution record of biotic recovery from foraminifers, understanding the physical and biological controls on changes in carbonate depositional style across the immediate end-Permian extinction horizon, documenting and interpreting the recovery of reef ecosystems during the Middle Triassic, and constraining environmental changes through high resolution stable isotope records of carbon, strontium, and calcium.

We have supplemented our field-based work with literature compilations of gastropod and foraminiferan occurrences so that we can test the extent to which local changes in the size and diversity fossils are likely to reflect global trends.

End-Triassic mass extinction

More recently, we have taken a similar approach to that described above regarding the end-Permian mass extinction to better constrain the biological and environmental circumstances of the end-Triassic mass extinction. In particular, we are interested in exploring the extent to which the end-Permian and end-Triassic mass extinction events may reflect similar forcing mechanisms. Chief among these is the hypothesis that each resulted from environmental changes driven by volatile release during flood basalt volcanism.