Tuatara are reptiles endemic to New Zealand and which, although resembling most lizards, are part of a distinct lineage, the order Rhynchocephalia. Their name derives from the Maori language, and means "peaks on the back". The two species of tuatara are the only surviving members of their order, which flourished around 200 million years ago. Their most recent common ancestor with any other extant group is with the squamates (lizards and snakes). 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 also includes birds, dinosaurs, and crocodiles).