Article
Reptile
Reptiles are a group of vertebrate animals that, like mammals, produce an amniote egg, with extra-embryonic sacs for waste, yolk, and protection, and often possessing a shell, particularly if released by the female before development of the embryo is completed. DNA analysis has allowed comparison of the genes in common for living organisms and new fossils have augmented our knowledge of the sequence of appearance of many features. Combined, these lines of research have produced changes from classical classification in which birds were regarded as most closely related to mammals primarily because they are both endothermic (able to maintain an internal body temperature). Now it is believed that each evolved this feature independently and that birds are derived from dinosaurs. Today's reptiles represent 2 main lines: Parareptilia or Chelonia (turtles) and Eureptilia or Diapsida, which contains the Lepidosauria (Tuatara, lizards and snakes) and Archosuria (crocodilians and birds).