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.
Besanosaurus
The bones of "Besanosaurus" were first discovered in "Sasso Caldo" quarry in the spring of 1993 by the volunteers of the paleontological group of Besano, a small town in the Lombardy region of north Italy. The fossil was almost completely embedded in the rock and could be first seen only through x-rays; to detect the content of the 38 slabs of stone enclosing the skeleton, 145 radiographs were necessary. The skeleton of "Besanosaurus" came to light in the paleontological laboratory of Museo Civico di Storia Naturale di Milano after 16500 hours of preparation. The preparators removed the rock enclosing the fossil step by step, working under a stereo microscope with chisels, needles and pins. The 38 slabs were reassembled and a silicon rubber matrix was made, from which a cast of the original specimen was obtained.