The common ancestor of all dinosaurs was certainly terrestrial, so logically that means birds are the descendants of terrestrial dinosaurs. That was in the Trias. By the Jurassic, small tree-climbing theropods with feathers were gliding and soon starting to fly.
They are.
The common ancestor of all dinosaurs was certainly terrestrial, so logically that means birds are the descendants of terrestrial dinosaurs. That was in the Trias. By the Jurassic, small tree-climbing theropods with feathers were gliding and soon starting to fly.