Pteranodon
While the first "Pteranodon" wing bones were collected by Marsh and Cope in the early 1870s, the first "Pteranodon" skull was found on May 2, 1876, along the Smoky Hill River in Wallace County (now Logan County), Kansas, USA, by Samuel Wendell Williston, a fossil collector working for Marsh. A second, smaller skull soon was discovered as well. These skulls showed that the North American pterosaurs were different from any European species, in that they lacked teeth and had bony crests on their skulls. Marsh recognized this major difference, describing the specimens as "distinguished from all previously known genera of the order Pterosauria by the entire absence of teeth." Marsh recognized that this characteristic warranted a new genus, and he coined the name "Pteranodon" ("wing without tooth") in 1876. Marsh reclassified all the previously named North American species from "Pterodactylus" to "Pteranodon". He considered the smaller skull to belong to "Pteranodon occidentalis", based on its size. Marsh classified the larger skull, YPM 1117, in the new species "Pteranodon longiceps", which he thought to be a medium-sized species in between the small "P. occidentalis" and the large "P. ingens". Marsh also named several additional species: Pteranodon comptus and "Pteranodon nanus" were named for fragmentary skeletons of small individuals, while "Pteranodon gracilis" was based on a wing bone that he mistook for a pelvic bone. He soon realized his mistake, and re-classified that specimen again into a separate genus, which he named "Nyctosaurus". "P, nanus" was also later recognized as a "Nyctosaurus" specimen.
Aublysodon
The first skeletal material referred to an original "Aublysodon" species was a partial skull unearthed in Jordan, Montana in 1966 and described by Ralph Molnar in 1977/1978. The skull, specimen LACM 28741 at forty-five centimetres the length of an average human arm, bore pointed teeth attached to a long narrow snout. First thought to be a juvenile "Tyrannosaurus", then interpreted as a large dromaeosaurid, this "Jordan theropod" was given the name "Aublysodon molnaris" by Gregory S. Paul in 1988; in 1990 the name was by Paul emended to "Aublysodon molnari", applying the correct genitive. It was made a separate genus "Stygivenator" by George Olshevsky in 1995, but was later, in 2004, reinterpreted to be a juvenile "Tyrannosaurus rex" by Thomas Carr and Tom Williamson. Another partial skeleton from New Mexico, specimen OMNH 10131, was in 1990 considered to represent "Aublysodon", but later research by Thomas Carr and Tom Williamson first referred it to "Daspletosaurus" and ultimately to "Bistahieversor". In 1988 Paul also created another species when renaming "Shanshanosaurus huoyanshanensis" Dong 1977 into "Aublysodon huoyanshanensis". It probably represents a "Tarbosaurus" specimen.