Reptiles are classified into distinct orders based on their evolutionary relationships, morphological features, and ecological roles. The main reptile orders are:
- Crocodylia: crocodiles, alligators, caimans, and gharials; large, aquatic, and semi-aquatic predators with strong jaws and armored skin.
- Squamata: lizards, snakes, and amphisbaenians; the largest order, characterized by movable jaws and, in many, the ability to shed skin.
- Testudines: turtles and tortoises; recognized by their bony or cartilaginous shell that encases the body.
- Rhynchocephalia: represented today by only one genus, Sphenodon (tuataras); ancient lineage with unique jaw mechanics and a "third eye" (parietal eye).
Amphibia is not a reptile order; it is a class distinct from Reptilia.
Lizards and snakes are members of the order Squamata.
The order Testudines includes turtles and tortoises, which have a protective shell.
The tuatara belongs to the order Rhynchocephalia.