Furthermore, birds resembled dinosaurs in that they walked on legs that held their bodies off the ground. Even today, most amphibians and reptiles crawl on their bellies. We now know that at least some dinosaurs cared for their young. A few reptiles and fishes do, but not many. Of course, birds continue the dinosaur tradition of caring for their young.
Birds are also warm-blooded.
Thus, they can live in far colder areas than reptiles and amphibians. Even some fishes and reptiles evolved the ability to retain their eggs inside their bodies, where they hatch. But birds remain oviparous, just laying eggs. On the other hand, being able to fly allows birds to lay their eggs in places that are tough for predators to reach. Page 5 Page 7 . . . . . . .