I saw this story on the Discovery Channel's website and thought it may be interesting since these people took a load of time into researching.


Jan. 21, 2005 — Global warming, not an asteroid impact, was to blame for the mass extinction of species 250 million years ago, an international team of researchers reports in the latest issue of Science magazine.

Paleontologists concluded that the disappearance of 90 percent of all marine species and 75 percent of land plants and animals at the boundary between the Permian and Triasic periods was caused by atmospheric warming from of greenhouse gases triggered by erupting volcanoes.
http://dsc.discovery.com/news/afp/20050117/warming.html