Tuataras (genus Sphenodon) are the only surviving members of the Order Rhynchocephalia, which was an abundant reptile group during the Mesozoic but largely disappeared in the Late Cretaceous. There are two recognized species of tuatara, Sphenodon punctatus and S. guntheri. Tuataras are found on relatively inaccesible islands off the coast of New Zealand. This endangered species was once widely distributed throughout New Zealand, but became extinct on the mainland before the arrival of European settlers.