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.
Massospondylus
The first fossils of "Massospondylus" were described by paleontologist Sir Richard Owen in 1854. Originally, Owen did not recognize these finds as those of a dinosaur; instead he attributed them to "large, extinct, carnivorous reptiles" that were related to today's lizards, chameleons and iguanas. This material, a collection of 56 bones, was found in 1853 by the government surveyor Joseph Millard Orpen in the Upper Elliot Formation at Harrismith, South Africa and was donated to the Hunterian Museum at the Royal College of Surgeons in London. Among the remains were vertebrae from the neck, back, and tail; a shoulder blade; a humerus; a partial pelvis; a femur; a tibia; and bones of the hands and feet. All these bones were found disarticulated, making it difficult to determine if all material belongs to a single species or not. However, Owen was able to distinguish three different types of caudal vertebrae, which he attributed to three different genera: "Pachyspondylus", "Leptospondylus" and "Massospondylus". "Massospondylus" was separated from the other two genera on the basis of its much longer caudal vertebrae, which also led to the scientific name that has been derived from the Greek terms "masson"/μάσσων 'longer' and "sphondylos"/σφόνδυλος 'vertebra'. However, later it was shown that the putative caudal vertebrae of "Massospondylus" were actually cervical vertebrae and that all the material probably belongs only to a single species. On May 10, 1941, the Hunterian Museum was demolished by a German bomb, destroying all the fossils; only casts remain.