My understanding is that the mass extinction that occurred about 65 million years ago and took out the dinos was not a cold vs warm blood thing but a big vs small. The big critters (dinos) died out and the small critters (mammals and reptiles) didn't. Incidentally there was a far worse extinction that occurred much earlier that took out the reptiles and cleared the way for the dinos. Mass extinctions are just nature's way of engaging in natural selection. As to books, I am not sure which are best. However, with all the recent Evolution series that have been out there should be some book tie ins for them. Kenneth "That's weird, it seems to have put my reply first. Maybe it will correct itself."