Definition of Reptilia
: a class of Vertebrata comprising air-breathing animals that have lungs but never gills, usually a three-chambered heart, two aortic arches from which the systemic arteries arise, a bony skeleton in which the skull articulates with the vertebral column by a single occipital condyle, the vertebrae gastrocentral, and the compound mandible articulate with the skull through a quadrate bone, that lack hair or feathers and have the skin more or less covered with horny epidermal plates or scales and relatively free from glands, that are known since the Carboniferous and as the dominant form of life in the Mesozoic, and that are represented in the recent fauna by the snakes and lizards, the turtles, the loricates, and the aberrant tuatara — see cotylosauria , loricata , mesosauria , pelycosauria , pterosauria , rhynchocephalia, squamata , testudinata , therapsida
