Rhynchocephalia are members of the Reptilia (see reptile), also known as the sphenodontida or 'beak-headed' reptiles, that lived during the Triassic period, 200 million years ago. Today, the only surviving genus is the tuatara (of which there are two species: Sphenodon punctatus and S. guntherii) found on islands off the coast of New Zealand. Although tuataras resemble lizards in many resembles, they don't, in fact, belong to any lizard family.