In a commentary in PNAS on recent new data regarding the causes of mass extinctions, former SFI researcher Doug Erwin suggests that the similarities of past extinction events may lie not with the triggering mechanisms, but in how the Earth’s biota responds to environmental insults.
Read Erwin's commentary in PNAS (February 12, subscription required)
Erwin is quoted in this article in The New York Times (February 20, 2014)