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.
Pteranodontoidea
Pteranodontoidea is an extinct clade of ornithocheiroid pterosaurs from the Early Cretaceous to the Late Cretaceous (middle Barremian to middle Campanian stages) of Asia, Europe, North America and South America. It was named by Alexander Wilhelm Armin Kellner in 1996. In 2003, Kellner defined the clade as a node-based taxon consisting of the last common ancestor of "Anhanguera", "Pteranodon" and all its descendants. Ornithocheiroidea is sometimes considered to be the senior synonym of Pteranodontoidea, however its depends on it definition. Ornithocheiroidea was originally defined as an apomorphy-based taxon by Christopher Bennett in 1994. Later, Kellner (2003) redefined it to represent the node of "Anhanguera", "Pteranodon", "Quetzalcoatlus" and "Dsungaripterus". Later, David Unwin (2003) suggested a different definition, the node that contains "Pteranodon longiceps" and "Istiodactylus latidens", thus making "Pteranodontoidea" a junior synonym of Ornithocheiroidea. Brian Andres (2008, 2010, 2014) in his analyses, converts Ornithocheiroidea using the definition of Kellner (2003) to avoid this synonymy.