Skin

Hindlegg of an Iguana, showing the iconic scales.

Reptilian skin is covered in a horny epidermis, making it watertight and enable reptiles to live on dry land, in contrast to the amphibians. Compared to mammals, reptilian skin is rather thin, and lack the thick dermal layer that produces leather in mammals. Exposed parts of reptiles are protected by horny scales or scutes, sometimes with a bony base, forming armour. In turtles, the body is hidden inside a hard shell composed on fused scutes. In the lepidosaurians like lizards and snakes, the whole skin is covered in epidermal scales (see Reptile scales). Such scales where once thought to be typical of the class Reptilia as a whole, but are really only found in the lepidosaurians. The scales found in turtles and crocodiles are of dermal origin rather than epidermal, and are properly termed scutes.