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. Major Groups of Existing Reptiles Crocodilians Crocodiles and alligators all live in or near water. The distinctive shell offers protection while conserving water and body heat.
Turtles lay their eggs on land, where predation is high.
Birds Birds apparently evolved from reptiles during the Jurassic. The body plan of birds is unique. The bones are lightweight because of air cavities within them. Powerful muscles are attached at strategic places on the bones for maximum leverage. The Rise of Mammals Distinctly Mammalian Traits Brain capacity is increased, allowing more capacity for memory, learning, and conscious thought.