Paleozoic era → Reptiles (292 MA)

Reptiles originated approximately 292 million years ago during the Carboniferous period. One of the oldest-known amniotes is Casineria, which had both amphibian and reptilian characteristics.

Nowadays, there are four main groups of reptiles: turtles and tortoises; lizards and snakes; crocodiles and alligators; and the tuatara. Many reptiles spend most of their time on land, but some spend a great deal of time in the water. Reptile species can be found in all types of habitat except polar ice and tundra.

All reptiles:

• Are vertebrates (which means they have a backbone or spine).

• Are ectothermic. Also known as “cold-blooded,” ectothermic animals cannot regulate their own body heat, so they depend on warmth from sunlight to become warm and active. If they get too hot, they have to find shade or a burrow to help them cool down.

• Are covered with scales.

• Have lungs for breathing.