Sphenodontidae is a family within the reptile group Sphenodontia. Most members of this family are only known from fossils but there is one living member, the tuatara (Sphenodon punctatus) from New Zealand. They were a quite ecologically diverse group, ranging from terrestrial carnivores and insectivores ( Sphenodon) to aquatic herbivores ( Ankylosphenodon) and durophagy ( Oenosaurus).
The following is a cladogram of Rhynchocephalia after Rauhut et al. (2012):