ornithoscelida

‖n. pl. [ NL., fr. Gr. 'o`rnis, 'o`rniqos, a bird + &unr_; a leg. ] (Zool.) A group of extinct Reptilia, intermediate in structure (especially with regard to the pelvis) between reptiles and birds. -- Or`ni*tho*scel"i*dan a. [1913 Webster]