Reptiles are egg laying vertebrates with scales as a body covering. They are ectothermic, which means they do not generate their own body heat. Instead, reptiles gain their body heat by basking in the sun. Reptiles come in many forms, ranging from the limbless snakes to deadly crocodiles. From scutteling lizards to shelled turtles. On top of these familiar creatures, there are many reptiles which are thought to be extinct. These include dinosaurs, pterosaurs and numerous marine reptiles.