rhynchocephalian

adjective

1. belonging or pertaining to the Rhynchocephalia, an order of lizardlike reptiles that are extinct except for the tuatara.

noun

2. a rhynchocephalian reptile.

adjective

1. of, relating to, or belonging to the Rhyncocephalia, an order of lizard-like reptiles common in the Mesozoic era but today represented only by the tuatara

noun

2. any reptile belonging to the order Rhyncocephalia

1. Any of various mostly extinct lizardlike reptiles of the order Rhynchocephalia, whose only living representative is the tuatara (Sphenodon punctatus and S. guntheri). Rhynchocephalians have several primitive skeletal features, including two temporal arches on each side of the skull rather than one, and teeth attached to the edge of the jaw rather than set in sockets. Most rhynchocephalians died out by the end of the Jurassic Period.