'order Ornithischia' definitions:

Definition of 'order Ornithischia'

(from WordNet)
noun
Extinct terrestrial reptiles having bird-like pelvises: armored dinosaurs (thyreophorans); boneheaded and horned dinosaurs (marginocephalians); duck-billed dinosaurs (euronithopods) [syn: Ornithischia, order Ornithischia]