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.
Patagosaurus
In the 1970s many specimens of a previously unidentified dinosaur were found associated together in the same bed and locality: a pebbly stratum near a route to Cerro Condor. The specimens were first described by Jose Bonaparte in 1979. For the fossil he erected the genus "Patagosaurus", as well as its type species "P. fariasi". The generic name of "Patagosaurus" comes from the location of its find in Patagonia, and the fact that it is a reptile. The specific name honours Ricardo Farias, on whose land the initial discovery was made. The genus was originally known from an almost complete postcranial skeleton lacking a skull as the holotype, and many referred specimens however in 2003 it was found that a dentary was referable to the species, so more specimens are probably this taxon. Its skeleton was found near those of "Piatnitzkysaurus" and "Volkheimeria" in the Callovian to Oxfordian aged Patagonian deposits of the Cañadón Asfalto Formation. "Patagosaurus" is almost completely known with many articulated specimens found covering almost all of the skeleton, including parts of the skull. Over twelve specimens have been referred to the species, although some of the material is probably from a unique taxon. Bonaparte (1986) assigned three specimens other than the holotype PVL 4170, PVL 4076, MACN CH 934, and MACN CH 933 to the genus. While the holotype includes a post cranial skeleton, the others are known from cranial material and a nearly complete juvenile skeleton and skull. MACN CH 933 is directly comparable with the type material of "Patagosaurus", which confirms its association with the genus. A specimen first referred to "Patagosaurus" in 2003, MPEF-PV 1670 (which includes just a lower jaw), is also very similar to MACN CH 934, and differences can be associated with age, so therefore, MPEF-PV 1670 presumably represents adult cranial material. However, the teeth of MACN CH 934 are very different from those of both lower jaws (MACN CH 933 and MPEF-PV 1670), so it can be identified as another sauropod from the same deposit as "Patagosaurus". Thus, the taxon only certainly includes PVL 4170, MACN CH 933, and MPEF-PV 1670.