Tuatara are reptiles endemic to New Zealand. The tuatara is a notable reptile endemic to New Zealand. Populations of the reptile tuatara have also been severely impacted. The diapsids are extremely diverse, and include all crocodiles, lizards, snakes, tuatara, turtles, and birds. Among other reptiles, squamates are most closely related to the tuatara, which superficially resembles lizards. TDSD is most common in turtles and crocodiles, but also occurs in lizards and tuatara. The tuatara ("Sphenodon punctatus") has been protected by law since 1895. Of all extant tetrapods, the parietal eye is most pronounced in the tuatara. The optimal body temperature for the tuatara is from , the lowest of any reptile. Several tuatara breeding programmes are active in New Zealand. The WildNZ Trust has a tuatara breeding enclosure at Ruawai. Williston proposed the Sphenodontia to include only tuatara and their closest fossil relatives in 1925.. Some experts believe that captive tuatara could live as long as 200 years. Williston proposed the Sphenodontia to include only tuatara and their closest fossil relatives in 1925. Tuatara sexes differ in more than size.