Pteranodon, the "Toothless Wing," is  a very well-known genus of pterosaur due to a lot of representation in both the fossil record and several popular movies and television shows. Showing a great degree of sexual  dimorphism, Pteranodon is a  fascinating prehistoric flying  reptile. Males grew to over six  meters from wingtip to wingtip and  had a very large crest; females were  smaller with wingspans that didn't quite reach four meters and shorter,  rounder crests. Though traditionally  the crest was thought to be used as  a rudder when flying, the range of  sizes of crests across the sexes means it likely was not used for  anything other than mating displays.  During the late Cretaceous Period, the center of the United States was an underwater paradise known as the  Western Interior Seaway, which was a small sea full of tasty creatures  for Pteranodon to feast on. Its diet  likely consisted of only fish, but  at least there were plenty of fish  in the sea for every pterosaur.  Pteranodon probably fished by  sitting on the water and plunging  their long beaks into the waves, but may have also been able to dive into the water to make spectacular  catches. On land, these creatures  walked on all-fours with their wings folded so that their small hands  could reach the ground.