What is "sphenodon"

Hatteria \Hat*te"ri*a\ (h[a^]t*t[=e]"r[i^]*[.a]), n. [NL.] (Zo["o]l.) A New Zealand lizard, which, in anatomical character, differs widely from all other existing lizards. It is the only living representative of the order Rhynchocephala, of which many Mesozoic fossil species are known; -- called also Sphenodon, tuatara, and Tuatera.

Sphenodon \Sphe"no*don\, n. [Gr. sfh`n a wedge + ???, ???, a tooth.] (Zo["o]l.) Same as Hatteria.

n. The tuatara.