Pteranodon is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 7 meters (23 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 was a pterosaur, meaning that it is not a dinosaur. By definition, all dinosaurs belong to one of the two groups within Dinosauria, i.e. Saurischia or Ornithischia. As such, this excludes pterosaurs. Nonetheless, Pteranodon is frequently featured in dinosaur media and are strongly associated with dinosaurs by the general public. While not dinosaurs, pterosaurs such as Pteranodon form a clade closely related to dinosaurs as both fall within the clade Avemetatarsalia.
Pteranodon was the first pterosaur found outside of Europe. Its fossils first were found by Othniel Charles Marsh in 1870, in the Late Cretaceous Smoky Hill Chalk deposits of western Kansas. These chalk beds were deposited at the bottom of what was once the Western Interior Seaway, a large shallow sea over what now is the midsection of the North American continent. These first specimens, YPM 1160 and YPM 1161, consisted of partial wing bones, as well as a tooth from the prehistoric fish Xiphactinus, which Marsh mistakenly believed to belong to this new pterosaur (all known pterosaurs up to that point had teeth). In 1871, Marsh named the find "Pterodactylus oweni", assigning it to the well-known (but much smaller) European genus Pterodactylus. Marsh also collected more wing bones of the large pterosaur in 1871. Realizing that the name he had chosen had already been used for Harry Seeley's European pterosaur species Pterodactylus oweni in 1864, Marsh re-named his giant North American pterosaur Pterodactylus occidentalis, meaning "Western wing finger," in his 1872 description of the new specimen. He also named two additional species, based on size differences: Pterodactylus ingens (the largest specimen so far), and Pterodactylus velox (the smallest).
Meanwhile, Marsh's rival Edward Drinker Cope also had unearthed several specimens of the large North American pterosaur. Based on these specimens, Cope named two new species, Ornithochirus umbrosus and Ornithochirus harpyia, in an attempt to assign them to the large European genus Ornithocheirus, though he misspelled the name (forgetting the 'e'). Cope's paper naming his species was published in 1872, just five days after Marsh's paper. This resulted in a dispute, fought in the published literature, over whose names had priority in what obviously were the same species. Cope conceded in 1875 that Marsh's names did have priority over his, but maintained that Pterodactylus umbrosus was a distinct species (but not genus) from any that Marsh had named previously. Re-evaluation by later scientists has supported Marsh's case, and found that Cope's assertion that P. umbrosus was a larger, distinct species were incorrect.