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.
Paleontology in Pennsylvania
One of the earliest notable events in Pennsylvania paleontology was the October 5th, 1787 presentation by Caspar Wistar and Timothy Matlack of a probable dinosaur metatarsal discovered in Late Cretaceous rocks near Woodbury Creek in New Jersey as "'a large thigh bone'" to the American Philosophical Society in Philadelphia. During the industrial revolution, Carboniferous-aged coal deposits in Pennsylvania were the sites of serendipitous discoveries of early fossil tetrapod trackways. Such discoveries generally occur when the excavation of coal mines removes the rock underlying the trackway, leaving it exposed on the tunnel's ceiling. Later, during the 1840s, Charles Lyell examined some local purported fossil bird and mammal tracks and found that they were actually petroglyphs left by local indigenous people. Depictions of trace fossils in indigenous rock art are known from throughout North America.