The non-avian reptiles of Australia are a diverse group of animals, widely distributed across the continent. Three of the four reptile orders are represented: Testudines, Squamata and Crocodilia. The only missing extant order is Sphenodontia, containing the tuataras, which are endemic to New Zealand. Australia has over 860 species, a large number in comparison to other continents; for example, North America's total is about 280. The most species-rich group is Squamata, the snakes and lizards. They are especially diverse in the arid areas of Australia, where other fauna are scarcer. Spinifex grass is a major habitat which allows them to remain in a relatively cool, moist area. Australia has a large array of reptiles which can be dangerous to humans. The world's largest reptile, the saltwater crocodile (Crocodylus porosus), is native to the continent's north coastal area.

Australian reptile families