Pteranodon
Pteranodon (; from Greek πτερόν ( pteron, "wing") and ἀνόδων (anodon, "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 8 meters (26 feet). They lived during the late Cretaceous geological period of North America in present-day Kansas, Alabama, Nebraska, Wyoming, and South Dakota. More fossil specimens of "Pteranodon" have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway.
Subhyracodon
Subhyracodon is an extinct genus of cow-sized rhinoceroses. With a length of 2.4 m (8 ft) and a weight estimated of 381.3 kg (in "S. mitis"), it was a tapir-sized herbivore on the plains of early Oligocene South Dakota 33 million years ago (White River Fauna), smaller than only the "Megacerops" and the chalicotheres. "Subhyracodon" had no horns, relying more on its speed to escape, but a species found at Wind Cave National Park had a pair of bony nasal ridges. The genus "Caenopus" and species originally referred to"Aceratherium" were synonymized into "Subhyracodon"