what is reptiles

Reptiles are a group of tetrapod vertebrates with an ectothermic ("cold- blooded") metabolism and amniotic development. They are characterized by their special skin made up of scales, bony plates, or a combination of both. Reptiles include animals such as crocodiles, snakes, lizards, turtles, and tuatara. They are generally less intelligent than mammals and rely on heat from their surroundings to warm up, as they do not maintain a constant internal body temperature. Most reptiles are oviparous, but some species are viviparous. Reptiles first appeared in the fossil record 315 million years ago and were the dominant animals during the Mesozoic era. They are part of the class Reptilia, which includes over 8,700 living species