Rhynchocephalia

Rhynchocephalia is an order of lepidosaurian reptiles containing the tuatara and extinct relatives. Its living members are represented by a single species, Sphenodon punctatus.

Lepidosauria: A reptile clade comprising snakes, lizards, and tuatara. Rhynchocephalians are one of Lepidosauria’s two major living branches.
Kinetic skull: A skull whose bones can move relative to one another during feeding. Tuatara lack the pronounced skull mobility characteristic of many lizards.
Rhynchocephalian fossil record: The collection of fossil evidence documenting extinct members of Rhynchocephalia. Fossils reveal a once-diverse order extending far beyond modern New Zealand.
Sphenodon punctatus: The living tuatara species native to New Zealand. This species is the sole surviving representative of Rhynchocephalia.
Tuatara: A New Zealand reptile and the sole living representative of Rhynchocephalia. Its anatomy and biology provide the only living evidence of the order.
Herpetological tooth replacement: The process by which reptiles replace worn or lost teeth. Tuatara do not replace their teeth once they are worn, unlike many reptiles.
Sphenodontia: A major rhynchocephalian lineage that includes tuatara and numerous extinct relatives. The group provides the principal evolutionary framework for tuatara and fossil relatives.
New Zealand tuatara conservation: The protection and recovery of tuatara populations in New Zealand. Conservation efforts determine the future of the order’s only living species.
Squamata: The reptile order containing lizards, snakes, and worm lizards. Squamates are the other major lepidosaur branch, distinct from rhynchocephalians.
Temperature-dependent sex determination: A reproductive system in which incubation temperature influences an offspring’s sex. Nest temperatures influence the sex of tuatara hatchlings.

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PleurosauridaeNarrower topic: Pleurosaurids were aquatic members of this broader reptile group.