Order Rhynchocephalia

an order of lizard-like reptiles that includes only one living species, the tuatara (Sphenodon punctatus) of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse group including a wide array of morphologically distinct forms. The oldest record of the group is dated to the Middle Triassic around 238 to 240 million years ago, and they had achieved a worldwide distribution by the Early Jurassic. Most rhynchocephalians belong to the group Sphenodontia ('wedge-teeth'), which are characterized by a hooked beak-like structure at the tip of the snout formed by enlarged premaxillary teeth. Their closest living relatives are lizards and snakes in the order Squamata.

tuataras