Today, scientists classify reptiles into four major groups known as "orders." These four reptile orders are as follows:
1. Crocodilia — crocodiles, gharials, caimans and alligators: 23 species
2. Sphenodontia — tuataras from New Zealand: 2 species
3. Squamata — lizards, snakes and amphisbaenids ("worm-lizards"): about 7,900 species
4. Testudines — turtles and tortoises: approximately 300 species