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.
Pteranodon
In 1910, Eaton became the first scientist to publish a more detailed description of the entire "Pteranodon" skeleton, as it was known at the time. He used his findings to revise the classification of the genus once again based on a better understanding of the differences in pteranodont anatomy. Eaton conducted experiments using clay models of bones to help determine the effects of crushing and flattening on the shapes of the arm bones Williston had used in his own classification. Eaton found that most of the differences in bone shapes could be easily explained by the pressures of fossilization, and concluded that no "Pteranodon" skeletons had any significant differences from each other besides their size. Therefore, Eaton was left to decide his classification scheme based on differences in the skulls alone, which he assigned to species just as Marsh did, by their size. In the end, Eaton recognized only three valid species: "P. occidentalis", "P. ingens", and "P. longiceps".