Why oh why are papers still being written as if there could be a proven single cause of mass extinctions. All the excellent work on the Permian-Triassic by Ward, Erwin and Benton shows a multitude of causes and all the competing theories on the KT will all have played a greater or less part in the event.
Dann Pigdon GIS / Archaeologist http://geo_cities.com/dannsdinosaurs Melbourne, Australia http://heretichides.soffiles.com ___________________________________________________________________