Definition of Rhynchocephalia
: an order of Reptilia that comprises forms resembling lizards but having biconcave vertebrae, immovable quadrate bones, and other peculiar osteological characters and that includes Sphenodon and numerous fossil genera — compare tuatara
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rhynchocephalian
\-lēən\ adjective or noun
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rhynchocephalic
\-¦falik\ adjective
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