Sphenodontia

The Sphenodontia is a diverse group of reptile. It includes only one living genus, the tuatara (Sphenodon). An alternative name for the order is the Rhynchocephalia.

Sphenodonts Temporal range: Upper Triassic – Recent
Sphenodon
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Sphenodontia Williston, 1925
Families
Gephyrosauridae Pleurosauridae Sphenodontidae

They are an offshoot from the evolutionary line leading to the lizards and snakes. They had many families during the late Triassic and Jurassic periods but then declined. They are now are the least successful of the lepidosaurs.^[1]

The only surviving member today is the New Zealand tuatara.