Research topic: bird

bird warm-blooded, egg-laying, vertebrate animal having its body covered with feathers and its forelimbs modified into wings , which are used by most birds for flight. Birds compose the class Aves (see Chordata ). There are an estimated 9,000 living species. Birds are believed to be extant members of a group of dinosaurs called maniraptors (other maniraptors include Velociraptor and Oviraptor ). They share with dinosaurs such characteristics as a foot with three primary toes and one accessory toe held high in back. Early avians include such primitive birds as Ar... Read more