Sphenodon punctatum, known as the tuatara lizard by the natives of New Zealand, is the only living species of reptile included in the order Rhynchocephalia and is considered by scientists to be the most ancient representative of reptile-like animals now living. All the other representatives of the order are known only as fossils. The rhychocephalians possess so called "abdominal ribs" which foreshadow the plastron of the chelonians.
Proceedings of the Iowa Academy of Science
©1923 Iowa Academy of Science, Inc.
"Observations on Sphenodon punctatum in Captivity,"
Proceedings of the Iowa Academy of Science, 30(1), 151-155.
Available at: https://scholarworks.uni.edu/pias/vol30/iss1/33