I have long felt that a combination of the comet and the Deccan Traps in India did away with most species. However, why birds, alligators, turtles and mammals survived, I can't begin to understand.
The Deccan Traps didn’t have anything to do with the K-T mass extinction. :’)
That kinda repetitive “Prehistoric Megastorms” DVD set (History Channel) has a bunch of excellent talking heads, and one of them explains that very thing. :’) I’ll try to find his name and do a web search to post something here. Just not tonight. ;’)