Had that massive meteor or comet not struck the Earth 65 million years ago, what would our world be like today? Would there still be dinosaurs? Would we have killed them all off ourselves by now? Might some be pets? Perhaps we might never have become the dominant animal?
IANAP (I Am Not A Paleontologist), but I just don’t think that mammals would have been able to evlove to the point at which we are now. Pointy teeth and tons of mass are a bitch to overcome. Our brains wouldn’t have had the time to evolve enough to think up strategies to avoid them.
Unless Steven Jay Gould was right about evolution occurring in fits, not a constant pace.