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2011 Annual Science Report

Massachusetts Institute of Technology Reporting  |  SEP 2010 – AUG 2011

Timescales of Events in the Evolution and Maintenance of Complex Life

Project Summary

For the first time, a precise and detailed chronology has been developed for numerous factors associated with the great mass extinction that ended to Paleozoic Era

4 Institutions
3 Teams
1 Publication
0 Field Sites
Field Sites

Project Progress

The end-Permian mass extinction was the most significant biodiversity crisis in earth history. To better constrain the timing, and ultimately the causes of this event, members of our team (Bowring, Rothman, Erwin, Cao and Ramezani) engaged in a collaboration with long-term colleagues at the Nanjing Institute of Geology and Paleontology) and others to establish a precise timescale for the geologic, isotopic and paleontological expressions of this event.

We measured a suite of geochronologic, isotopic and biostratigraphic data on several well-preserved sedimentary sections in South China. High-precision U-Pb dating reveals that the extinction peak occurred just before 252.28 0.08 Ma, following a decline of 2 per mil in δ13C over 90,000 years, and coincided with a δ13C excursion of -5 per mil that is estimated to have lasted less than 20,000 years. The extinction interval was less than 200,000 years, and synchronous in marine and terrestrial realms; associated charcoal-rich and soot-bearing layers indicate widespread wildfires on land. A massive release of carbon dioxide and/or methane may have caused the catastrophic extinction.