| Summary: | Reptiles arose about 310-320 million years ago during the Carboniferous period. Reptiles are defined as animals that have scales, lay land based hard shelled eggs, and possess cold-blooded metabolisms. Today reptiles generally rank low in most ecological food chains, containing very few apex predators, but many examples of apex reptiles have existed in the past. Although reptiles have lower species variation than in the past, they have an extremely diverse evolutionary history that has led to biological successes such as dinosaurs, mammals, and birds. Reptiles first arose from amphibians in the swamps of the late Carboniferous. Increasing evolutionary pressure and the vast untouched niches of the land powered the evolutionary changes in amphibians to gradually become more and more land based. Environmental selection propelled the development of certain traits, such as a stronger skeletal structure, muscles, and more protective coating (scales) became more favorable, the basic foundation of reptiles were founded. The evolution of lungs and legs are the main transitional steps towards reptiles, but the development of hard-shelled external eggs replacing the amphibious water bound eggs is the defining feature of the class reptilia specifically, the enlarged cerebrum and cerebellum. Although there brain size is small when compared to mammals and birds, these enhancements prove vital in hunting strategies of reptiles. The increased size of these two regions of the brain allowed for improved motor skills and an increase in sensory development.
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