Source : Webster's Revised Unabridged Dictionary (1913)

Thecodontia \The`co*don"ti*a\, n. pl. [NL.] (Paleon.)
   A group of fossil saurians having biconcave vertebr[ae] and
   the teeth implanted in sockets.

Source : WordNet®

Thecodontia
     n : extinct terrestrial reptiles having teeth set in sockets; of
         the late Permian to Triassic [syn: {order Thecodontia}]