Pteranodon
"Pteranodon" was the first pterosaur found outside of Europe. Its fossils first were found by Othniel Charles Marsh in 1870, in the Late Cretaceous Smoky Hill Chalk deposits of western Kansas. These chalk beds were deposited at the bottom of what was once the Western Interior Seaway, a large shallow sea over what now is the midsection of the North American continent. These first specimens, YPM 1160 and YPM 1161, consisted of partial wing bones, as well as a tooth from the prehistoric fish "Xiphactinus", which Marsh mistakenly believed to belong to this new pterosaur (all known pterosaurs up to that point had teeth). In 1871, Marsh named the find ""Pterodactylus oweni"", assigning it to the well-known (but much smaller) European genus "Pterodactylus". Marsh also collected more wing bones of the large pterosaur in 1871. Realizing that the name he had chosen had already been used for Harry Seeley's European pterosaur species "Pterodactylus oweni" in 1864, Marsh re-named his giant North American pterosaur Pterodactylus occidentalis, meaning "Western wing finger," in his 1872 description of the new specimen. He also named two additional species, based on size differences: Pterodactylus ingens (the largest specimen so far), and Pterodactylus velox (the smallest).
Stenonychosaurus
A more complete skeleton of "Stenonychosaurus" was described by Dale Russell in 1969 from the Dinosaur Park Formation, which eventually formed the scientific foundation for a famous life-sized sculpture of "Stenonychosaurus" accompanied by its fictional, humanoid descendant, the "dinosauroid". "Stenonychosaurus" became a well-known theropod in the 1980s, when the feet and braincase were described in more detail. Along with "Saurornithoides", it formed the family Saurornithoididae. Based on differences in tooth structure, and the extremely fragmentary nature of the original "Troodon formosus" specimens, saurornithoidids were thought to be close relatives while "Troodon" was considered a dubious possible relative of the family. Phil Currie, reviewing the pertinent specimens in 1987, showed that supposed differences in tooth and jaw structure among troodontids and saurornithoidids were based on age and position of the tooth in the jaw, rather than a difference in species. He reclassified "Stenonychosaurus inequalis" as well as "Polyodontosaurus grandis" and "Pectinodon bakkeri" as junior synonyms of "Troodon formosus". Currie also made Saurornithoididae a junior synonym of Troodontidae. In 1988, Gregory S. Paul went farther and included "Saurornithoides mongoliensis" in the genus "Troodon" as "T. mongoliensis", but this reclassification, along with many other unilateral synonymizations of well known genera, was not adopted by other researchers. Currie's classification of all North American troodontid material in the single species "Troodon formosus" became widely adopted by other paleontologists, and all of the specimens once called "Stenonychosaurus" were referred to as "Troodon" in the scientific literature through the early 21st century.