Reptiles, a various group of air-breathing vertebrates, are characterized by their scaly pores and skin, amniotic eggs, and ectothermic (chilly-blooded) metabolism. They are really traditionally classified into four living orders: Crocodilia (crocodiles and alligators), Sphenodontia (tuataras), Squamata (lizards and snakes), and Testudines (turtles