Tuatara are reptiles endemic to New Zealand, belonging to the genus Sphenodon. Although resembling most lizards, they are part of a distinct lineage, the order Rhynchocephalia. Their name derives from the Māori language, and means "peaks on the back". The single species of tuatara (Sphenodon punctatus) is the sole surviving member of its order, which originated in the Triassic period around 250 million years ago and which flourished during the Mesozoic era. Their most recent common ancestor with any other extant group is with the squamates (lizards and snakes). For this reason, tuatara are of interest in the study of the evolution of lizards and snakes, and for the reconstruction of the appearance and habits of the earliest diapsids, a group of amniote tetrapods that also includes dinosaurs (including birds) and crocodilians.