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.
Thalassodromeus
The first known "Thalassodromeus" specimen was collected in 1983 near the town of Santana do Cariri in the Araripe Basin of northeastern Brazil. Found in outcrops of the Romualdo Formation, it was collected over a long period of time in several pieces. The specimen (catalogued as DGM 1476-R at the Museu de Ciências da Terra) was preserved in a calcareous nodule, and consists of an almost-complete, three-dimensional skull (pterosaur bones are often flattened compression fossils), missing two segments of the bottom of the skull and mandible and the front of the lower jaw. The left jugal region and right mandibular ramus (half of the mandible) are pushed slightly inward. The skull was first reported in a 1984 Italian book, and preliminarily described and figured in 1990 by palaeontologists Alexander W. A. Kellner and Diogenes de Almeida Campos. Although the pieces of skull had been divided between museums in South and North America, they were assembled before 2002.
In 2002, Kellner and Campos described and named the new genus and species "Thalassodromeus sethi", skull DGM 1476-R being the holotype specimen. The generic name is derived from the Ancient Greek words θάλασσα ("thálassa", "sea") and δρομεύς ("dromeús", "runner"), meaning "sea runner" in reference to the animal's supposed skim-feeding behaviour. The specific name refers to the ancient Egyptian god Seth. The specimen was not fully prepared at the time of this preliminary description. The original describers chose the name "sethi" because the crest of the pterosaur was supposedly reminiscent of the crown worn by Seth; however, the palaeontologists André Jacques Veldmeijer, Marco Signore, and Hanneke J. M. Meijer pointed out in 2005 that the crown (with its two tall plumes) was typically worn by the god Amon (or Amon-Ra) and his manifestations—not by Seth.