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.
Istiodactylus
Istiodactylus is a genus of pterosaur that lived during the Early Cretaceous period, about 120 million years ago. The first fossil was discovered on the Isle of Wight in England, and became the holotype specimen of a new species, "O. latidens" (Latin for "wide tooth"), in the genus "Ornithodesmus" in 1901. This species was moved to its own genus, "Istiodactylus", in 2001; this name is Greek for "sail finger". More specimens were described in 1913, and "Istiodactylus" was the only pterosaur known from three-dimensionally preserved fossils for much of the 20th century. In 2006, a species from China, "I. sinensis", was assigned to "Istiodactylus", but it has since been found to belong to a different genus.