Like, I’m aware of there being exceptions like Penguins, Ostriches, and Bats. But in general, why is there such a distinct land/air split between mammals and birds? Why don’t mammals share the ground with ecosystems of plant- and meat-eating walking birds? Why didn’t we get birds that evolved to slither like snakes, or tunnel like rodents? Why isn’t it (land+sky) all just mammals, where we’d have parrot- and vulture-like bats that don’t lay eggs? If we started the simulation again, might things like this evolve?
Well, yes, where else would the flying dinosaurs come from?
That it was more of a direct path from say raptors to chickens, but I mentioned in another reply that I had forgotten about all the different dinosaur eras and the hundreds of millions of years between them all.