The class Reptilia is divided into four orders: Turtles, Lizards and Snakes, Crocodiles, and the Tuatara. The living reptiles are comprised of Turtles (order Chelonia) about 250 species; the Lizards and Snakes (order Squamata) about 5700 species; the Crocodilians (order Crocodylia), 23 species; and the Tuatara (order Rhynchocephalia) only one species.
Reptiles are cold blooded vertebrate animals. Many characteristics define Reptiles, some of which are dry scaled skin, internal fertilization, and a three to four chambered heart. They inhabit many environments. But most, channeled by cold bloodedness, are confined to warmer habitats. Reptiles may be aquatic, semi-aquatic or terrestrial, as well as arboreal.
Reptiles range in size considerably. The longest reptile is the reticulated python, reaching 33 feet in length. The smallest Reptile is possibly the dwarf gecko that reaches only about 1.3 inches in length.
The Reptilian skull ranges from the reduced, loosely joined, or kinetic skull of snakes to the large, solid skull of the crocodiles. One characteristic identifying a reptile skull is a single ball-and-socket connection (condyle) at the head-neck joint instead of two, as in mammals, and an incomplete or complete partition (the secondary palate) along the roof of the mouth, separating the food and air passageways so that breathing can continue while the food is being chewed.
ORDERS in the Class Reptilia