Bird

Birds (class Aves) are bipedal, warm-blooded, egg-laying vertebrate animals. Birds evolved from theropod dinosaurs during the Jurassic, and the earliest known bird is the Late Jurassic Archaeopteryx. Ranging in size from tiny hummingbirds to the huge Ostrich and Emu, there are between 9,000-10,000 known living bird species in the world, making them the most diverse class of terrestrial vertebrates.