Dodo Bird

A Dodo bird. Although it cannot fly like most birds, it would have to be a bird because of the feathers. The fact that it has wings also makes it a bird. Although it lays eggs, so do fish, amphibians, and reptiles. Running around on the ground rules out fish. Even if you never saw one alive, you would know it was a bird. What else would it tell you, that you could not find out from if you examined one in a museum? You would know it was warm-blooded.