These unusual creatures live burrowed in the forest floor where they hunt for invertebrate prey. They have no limbs but do have small scales embedded in the skin. Modification of limb bones, teeth, and jaw bones allowed greater exploitation of the insect life emerging in the Late Carboniferous. Development of the cortex region of the cerebrum permitted greater integration of sensory input and motor response. A four-chambered heart and more efficient lungs allowed greater activity.
Reptiles have a scaly skin that is resistant to drying.
They have a copulatory organ that permits internal fertilization. Their kidneys are good at conserving water. The produce amniote eggs with covering membranes and a shell, which allow the eggs to laid in dry habitats. C. Crocodiles and alligators all live in or near water. They show complex behavior, as when the parents guard nests and assist hatchlings into the water.