Forgive me for outlining this in basic.<quoted text>
Hold on I thought some meteorite hit the earth and killed the dinosaurs it the dinos were dead how'd they evolve?
1. all species are constantly evolving. No species is not evolving - evolution is constant.
2. Long before the meteor, dinosaurs had evolved into several phyogeneies (evolutionary lineages). The avians were one of these - and the only lineage from the dinosaurs to survive. The other ones all went extinct.
I'm not a dinosaur expert, I really can't speak to dinos. But I'm pretty sure dinos were starting to have problems before the meteor - at least, Baker presents a pretty compelling argument for that.