The tuatara is an amniote of the family Sphenodontidae, endemic to New Zealand. The two species of tuatara are the only surviving members of the Sphenodontians who flourished around 200 million years ago, and are in the genus Sphenodon. Tuatara resemble lizards, but are equally related to lizards and snakes, both of which are classified as Squamata, the closest living relatives of tuatara. For this reason, tuatara are of great interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsids (the group that additionally includes birds and crocodiles). (Full article...)