the 6 mi. dia. asteroid striking at chixilub (sp?) is being attributed with the dino-destruction as it was the worst location to have happened at. I think the claim is there was lots of sulfur bearing stone there as well as being on the coast. No telling what a smack like that could do to vulcanism around the world as well. Evidently, something that big was able to start fires world wide from returning materials crashing around the world.

Whether it was the sole cause or not may forever be uncertain. It seems plausible and IMHO, a great example of the scientific method at work. Since it's at the crossroads of a number of different disciplines, I expect there will always be some conflicting views that will probably all exist as 'mainstream'.