REPTILES Biology 112

The Evolution of Reptiles from Amphibians As Earth became drier, amphibians started to die out New habitats for reptiles emerged The Mesozoic Era is known as the Age of Reptiles (dinosaurs were very common) This ended with a mass extinction at the end of the Cretaceous Period

Characteristics of Reptiles Vertebrates adapted for life on land Adaptations from amphibians include: Dry skin covered with protective scales Scales help with water retention in the body Well-developed lungs Eggs have a shell and several membranes

Adaptations for Life on Land Regulate their body temperature through their behavior – ectotherms Varied diet with different ways of eating Lungs have greater surface area for gas exchange as well as muscles that allow the chest to expand and collapse Double loop circulation system Eliminate wastes as urine with little water so as to conserve water in the body Faster response and well-developed sense organs Larger and stronger limbs Internal fertilization laying eggs that develop outside the mother’s body – embryo is surrounded by an amniotic sac that prevents it from drying out

Four Main Groups of Reptiles 1. Lizards and Snakes - Lizards have legs, clawed toes, external ears, movable eyelids - Snakes are legless 2. Crocodilians - long, broad snouts and a squat appearance - Fierce carnivores that live in tropical areas - Ex. Alligators, crocodiles, caimans, and gavials 3. Turtles and tortoises - Have backbones fused to a protective shell - Usually live in water - Have horny ridges instead of teeth 4. Tuatara - Somewhat like lizards but lack external ears and scales - Also have a ‘third eye’, which is a sense organ on top of the brain