I saw a vision of a raptor jumping up and flapping its arms as it crashed into the ground. I think this is the evolution of flight, which is that of jumping dinosaurs.
This needs quite a bit more work to be a topic. If you are just interested in avian evolution from theropod dinosaurs then there are a number of extant threads on that topic such as Archaeopteryx and Dino-Bird Evolution.
If you have a specific question in mind then let me know.