Comment by adastra22

You do know that there was an already well studied global mass extinction, the P-T crisis, which is very well studied and clearly the result of volcanism?

I think you are exhibiting exactly the problem with the Alvarez hypothesis that makes people have such a gut reaction to it. It is a Deus Ex Machina that can be invoked at any time to explain a die off even in the face of conclusive evidence to the contrary.