The Collaborative International Dictionary of English v.0.48:

Pterosaur \Pter"o*saur\, n. [Gr. ? wind + ? a lizard.] (Paleon.)
   A pterodactyl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pterosaur
    n 1: an extinct reptile of the Jurassic and Cretaceous having a
         bird-like beak and membranous wings supported by the very
         long fourth digit of each forelimb [syn: pterosaur,
         flying reptile]