Thecodontia
  槽齒目
  The·co·don·ti·a n. pl.  Paleon. A group of fossil saurians having biconcave vertebrae and the teeth implanted in sockets.
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  Thecodontia
       n : extinct terrestrial reptiles having teeth set in sockets; of
           the late Permian to Triassic [syn: order Thecodontia]