Extinction of Dinosaurs: Consensus Reached . . . mostly

Except nobody is saying it was total extinction. It's not even the worst ever: the previous P-Tr event wiped out far more species (percentagewise) and yet there was still plenty enough life left over to begin the age of the dinosaurs.Everything that weighed over 20 pounds, IIRC, was killed because there was simply no way to support it. But a lot of the smaller stuff i.e. mammals and birds could survive, and once the environments were stable enough, they developed, speciated, evolved to fill the gaps left behind.Not all dinosaurs changed into birds. A majority of them stayed being dinosaurs. The largest birds -- the ones that were too big -- died. Not changed into smaller ones, died. The smaller ones lived, and later diversified to include large birds again. As a matter of fact, modern monkeys look much like their ancestors. Even we are very similar; the only significant differences are the lack of hair and our bipedalism. The rest is all pretty much the same; differences in bone lengths and sizes, brain size, and probably some basic abilities.