Theories regarding the cause of the Permian Extinction

  1. The continents coalesced -Gould

  2. There was a deadly drop in sea level - Erwin -

For an interesting theory of why the continents might have coalesced, see an article by . Harold Tressman

The Permian Extinction may have wiped out all but 4 percent of species - Gould

There was no excess iridium at that level. Goldsmith