Truly modern birds appeared emerged 100 million years ago, way before the massive extinction which wiped out the dinosaurs. While they were never really on top of the food chain, they are the only branch of dinosaurs to survive past the Cretaceous (if you haven’t already, get used to the idea: birds are dinosaurs).
Remember dinosaurs lived and evolved over several hundred million years prior to the Extinction event. T-Rexes as an example did not evolve until late in the dinosaur era, yet the different types 150 million years earlier are dinosaurs as well.
Birds are the only group to survive the extinction and have continued to evolve over the last 60 million years like they did the 100 million prior to that when they had more Dino company. The birds today are true dinosaurs. And I think that's fascinating.