The history of reptiles began when the first reptiles evolved from amphibians. Fossils of the first reptiles have been found in deposits from the early Carboniferous period (359-299 mya) and possessed characteristics that made them greatly resemble lizards; they were small in size, had four legs, were vertebrates, and possessed teeth that classified them as insectivores. These reptiles flourished due to the sheer amount of insects available around them, and by the end of the Permian period (299-251 mya) they had become the dominant land vertebrates. The Permian Period ended with the formation of Pangaea. Reptiles were successful in the interior of Pangaea because of the arid climate that they were adapted to; however, the end of the Permian …show more content…
Most reptiles have a heart with three chambers, excluding crocodiles, who have four chambers. The reptilian heart is unique in that it is able to divert deoxygenated blood to the body instead of the lungs, which can raise body temperature quickly. Reptiles possess large lungs which are frequently divided into chambers. The lining of the lungs are folded into alveoli which increase the amount of oxygen that can be absorbed. They respirate by expanding their rib cages, much like humans do. Reptiles have brains around the size of the amphibian brain, but they possess a much larger cerebrum. They utilize vision, hearing, smell, and heat detection. Most reptiles possess a specialized sense organ known as Jacobson’s organ, which is sensitive to odors. Reptiles are ectotherms who control body temperature through thermoregulation, the process where they raise their body temperature by absorbing heat from the surrounding …show more content…
3,000 species of lizards exist today. Lizards include iguanas, chameleons, and geckos. They are found on every continent excluding Antarctica. Most lizards feed on insects or small animals, but a few of the larger species-like the chuckwalla and desert iguana-consume plants. The largest monitor, the komodo dragon, eats substantial prey such as goats and deer. In order to elude predators, most lizards rely on their speed, agility, and camouflage abilities; some are able to detach their tails to redirect the attention of predators. Lizards are mostly small, with the largest belonging to the monitor family. Concerning snakes, 2,500 species of these reptiles exist. They lack legs and possess a distinct anatomy: a backbone of 100 to 400 vertebra with a pair of ribs attached to each vertebra. Snakes can seize or swallow prey, but most use one of two methods to kill: constriction or the injection of venom through fangs. Snakes that constrict are known as constrictors, snakes that inject poison are known as elapid snakes, and vipers inject venom. Prey is swallowed whole by