Reptiles are vertebrate, or backboned animals constituting the class Reptilia and are characterized by a combination of features, none of which alone could separate all reptiles from all other animals. The characteristics of reptiles are numerous, therefore can not be explained in great detail in this report. In no special order, the characteristics of reptiles are: cold-bloodedness; the presence of lungs; direct development, without larval forms as in amphibians; a dry skin with scales but …showed first 75 words of 1080 total…

…showed last 75 words of 1080 total…Cotylosauria, which evolved from an amphibian labyrinthodont stock. It is also quite clear that the coty losaurs early divided into two lines, one of which (the pelycosaurs) represented the stock that gave rise to the mammals. Another branch led to all of the other reptiles, and later, to the birds as well. Thus, most of the questions of reptilian evolution and classification deal with the reptiles' interrelationship, rather than with their relationships with other animals.