The order Rhynchocephalia contains only two living species, both commonly known as the tuatara. Externally, this ancient reptile resembles a lizard, but internally is very unique.Tuataras only live on the islands of New Zealand. Although they might superficially resemble lizards, tuataras are not in any lizard family. Rather, they come from a sister group to lizards and snakes. Some of the things that make tuataras different from lizards are their lack of external ears, a more formed parietal eye and a lack of hemipenes or even a penis in general.