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 1892, Samuel Williston examined the question of "Pteranodon" classification. He noticed that, in 1871, Seeley had mention the existence of a partial set of toothless pterosaur jaws from the Cambridge Greensand of England, which he named "Ornithostoma". Because the primary characteristic Marsh had used to separate "Pteranodon" from other pterosaurs was its lack of teeth, Williston concluded that "Ornithostoma" must be considered the senior synonym of "Pteranodon". However, in 1901, Pleininger pointed out that "Ornithostoma" had never been scientifically described or even assigned a species name until Williston's work, and therefore had been a "nomen nudum" and could not beat out "Pteranodon" for naming priority. Williston accepted this conclusion and went back to calling the genus "Pteranodon". However, both Williston and Pleininger were incorrect, because unnoticed by both of them was the fact that, in 1891, Seeley himself had finally described and properly named "Ornithostoma", assigning it to the species "O. sedgwicki". In the 2010s, more research on the identity of "Ornithostoma" showed that it was probably not "Pteranodon" or even a close relative, but may in fact have been an azhdarchoid, a different type of toothless pterosaur.