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