Pteranodontoidea

Pteranodontoidea (or pteranodontoids, from Greek meaning "toothless wings") is an extinct clade of ornithocheiroid pterosaurs from the Early to Late Cretaceous (early Valanginian to late Maastrichtian stages) of Asia, Africa, Europe, North America and South America. It was named by Alexander Wilhelm Armin Kellner in 1996. In 2003, Kellner defined the clade as a node-based taxon consisting of the last common ancestor of Anhanguera, Pteranodon and all its descendants. The clade Ornithocheiroidea is sometimes considered to be the senior synonym of Pteranodontoidea, however it depends on its definition.Unwin, D. M., (2003): On the phylogeny and evolutionary history of pterosaurs. pp. 139-190. — in Buffetaut, E. & Mazin, J.-M., (eds.): Evolution and Palaeobiology of Pterosaurs. Geological Society of London, Special Publications 217, London, 1-347 Brian Andres (2008, 2010, 2014) in his analyses, converts Ornithocheiroidea using the definition of Kellner (2003) to avoid this synonymy. A preview that shows the cladogram without clade names

Despite the meaning of the group's name, not all pteranodontoids were toothless, the earlier genera such as the istiodactylids and anhanguerids had teeth that they used to catch prey, and several conclusions had led to the idea that they later evolved into the toothless pteranodontids. Pteranodontoids were also the most diverse group of pterosaurs throughout the Cretaceous period, and therefore the most successful flyers during their time. They were mostly replaced by the larger azhdarchids at the end of the Late Cretaceous however, which resulted in resource and terrain competitions, but even so, pteranodontoids still managed to thrive with them, and genera such as Alcione, Barbaridactylus, and Simurghia lived until the Cretaceous-Paleogene extinction event. Pteranodontoids had similar a similar diet to modern-day soaring birds such the albatross, which mainly consisted of fish. Some genera of this group however, fed mainly on carrion, this can be seen on the earlier genera such as Istiodactylus. They were also known for their proportionally large wingspans, the largest recorded of any pteranodontoid reached , and it belongs to the genus Tropeognathus.

History of early discovered genera

Several fossil remains were found in the Chalk Formation of England, a chalk pit known for its wide variety of fossils belonging to different animals. British paleontologist James Scott Bowerbank named and described the specimens found as a new species of Pterodactylus, P. giganteus due to its much larger size. P. giganteus is nowadays considered to belong to the genus called Lonchodraco. In 1851, Bowerbank unearthed more specimens in the same chalk pit as P. giganteus, and assigned these specimens to yet another newly named species of Pterodactylus, known as P. cuvieri, in honor of the German naturalist and zoologist Georges Cuvier. Later that year, British paleontologist Sir Richard Owen had also unearthed several fossil specimens in the Chalk Formation, in which he assigned them as Pterodactylus compressirostris during its description.Owen, R. (1851). Monograph on the fossil Reptilia of the Cretaceous Formations. The Palaeontographical Society 5(11):1-118. Owen later unearthed many fossil specimens from a different fossil site called the Cambridge Greensand, he then assigned these specimens into a new species called Pterodactylus simus. With the naming of this new species, British paleontologist Harry Govier Seeley created a new separate genus called Ornithocheirus (from Ancient Greek "ὄρνις", meaning "bird", and "χεῖρ", meaning "hand"), due to the notion of the time, in which pterosaurs were the direct ancestors of birds. In 1870, Seeley then also reassigned Pterodactylus cuvieri into a new species called Ornithocheirus cuvieri.Seeley, H.G., 1869, Index to the fossil remains of Aves, Ornithosauria, and Reptilia, from the Secondary System of Strata, arranged in the Woodwardian Museum of the University of Cambridge. St. John's College, Cambridge 8: 143. Seeley, H.G. (1870). The Ornithosauria: an Elementary Study of the Bones of Pterodactyles. Cambridge, 130 pp. This species is now considered to belong to the genus Cimoliopterus. Back in 1874 however, controversies between the naming of species and genera of these pterosaurs started, with the paleontologists Harry Seeley and Richard Owen fighting over reassignings of different species as well as genera. Owen therefore created two new genera: Coloborhynchus (meaning "maimed beak") and Criorhynchus (meaning "ram beak"), in reference to their unique convex "keeled" crests on top, and underside of their snout. Owen then created a type species for Coloborhynchus, C. clavirostris, and sunk three species which were assigned previously to Ornithocheirus, and Criorhynchus consisted entirely of former Ornithocheirus species.Owen, R. 1874, Monograph on the fossil Reptilia of the Mesozoic Formations. Palaeontographical Society, London, 14 pp Later in 1881 however, Seeley disagreed with Owen's conclusions, and he therefore assigned the species he named Ornithocheirus simus as the type species of Ornithocheirus.

The naming of the different pterosaur species, as well as the genus Ornithocheirus in England resulted in further research in other places. In the United States, American paleontologist Othniel Charles Marsh led an expedition to the Smoky Hill Chalk deposits in western Kansas in 1870.Betts, C. W. 1871. The Yale College Expedition of 1870. Harper's New Monthly Magazine, 43(257):663–671 Marsh unearthed the first ever specimens of pterosaur from North America (specimens YPM 1160 and YPM 1161), which now belong to the genus Pteranodon, and consisted of partial wing remains and a tooth of the fish Xiphactinus, which Marsh had once believed that it belonged to Pteranodon.Marsh, O. C. 1871. Scientific expedition to the Rocky Mountains. American Journal of Science, ser. 3, 1(6):142–143. In 1871, he assigned these specimens to a new species called "Pterodactylus oweni" (meaning "Owen's wing finger"),Marsh, O. C., 1871. "Note on a new and gigantic species of Pterodactyle." American Journal of Science, ser. 3, 1(6):472 in honor of Sir Richard Owen, but he realized that the name he had chosen had already been used for a different European pterosaur species described by Harry Seeley, so he renamed his discovery as Pterodactylus occidentalis (meaning "Western wing finger"), in reference to the location where it was found.Marsh, O. C. 1872. Discovery of additional remains of Pterosauria, with descriptions of two new species. American Journal of Science, Series 3, 3(16):241–248. American paleontologist Edward Drinker Cope had also unearthed several remains of the large North American pterosaur, and based on these remains, Cope named two new species, Ornithochirus umbrosus and Ornithochirus harpyia, in an attempt to assign them to the large European genus Ornithocheirus, but he had missed the 'e' when describing them. The paper naming these species by Cope's paper naming had been published in 1872, just five days after the publication of Marsh's paper. This led to a dispute between the two paleontologists, which both fought over whose names had priority to the published literature, in what was obviously the same species of pterosaur.

In 1876, Marsh had described the first skull specimen of Pteranodon, which as unearthed by American paleontologist Samuel Wendell Williston in the Smoky Hill River, located in the Wallace County (now Logan County) of Kansas, USA. Later that year, another skull specimen was found, though this time a bit smaller in size. Soon enough, Marsh recognized a major difference when he described these specimens, they lacked teeth and had bony crests on their skulls. He then described the specimens found as "distinguished from all previously known genera of the order Pterosauria by the entire absence of teeth." Marsh then coined the name Pteranodon (meaning "wing without tooth"), and pointed that the unique characteristics identified warranted a new generic name. Marsh had also reclassified all the previously named North American species from Pterodactylus to Pteranodon, and considered the smaller skull to belong to the reassigned Pteranodon occidentalis based on its size.Bennett, S.C. (2000). "Inferring stratigraphic position of fossil vertebrates from the Niobrara Chalk of western Kansas." Current Research in Earth Sciences: Kansas Geological Survey Bulletin, 244(Part 1): 26 pp. Specimens of smaller individuals were later uncovered, and Marsh had also named several additional species: Pteranodon comptus and Pteranodon nanus, based on these distinct and smaller fragmentary skeletons. He then created another separate species called Pteranodon gracilis, which is now based on a wing bone that he previously mistook for a pelvic bone. Marsh soon realized his mistake, and therefore reassigned that specimen he found into a separate genus which he named Nyctosaurus, and the species P. nanus was soon recognized as a Nyctosaurus specimen as well, this is due to the synapomorphies seen in both. Witton, M. (2010). Pteranodon and beyond: The history of giant pterosaurs from 1870 onwards. Geological Society of London, Special Publications. 343. 313-323. Later in 1892, Samuel Williston had become the first scientist to critically evaluate all of the Pteranodon species classified by Cope and Marsh. He agreed with most of Marsh's reassignings and classifications, but several exceptions were still made. Williston revised his earlier conclusion in 1903, in which he stated that there were only three species of Pteranodon, instead of seven. He also considered both P. comptus and P. nanus to be specimens of Nyctosaurus, and divided the other species into small (P. velox), medium (P. occidentalis), and large species (P. ingens), based primarily on the shape of their upper arm bones. He also followed his first conclusion of P. longiceps being a synonym of either P. velox or P. occidentalis based on its size.Williston, S. W. 1903. On the osteology of Nyctosaurus (Nyctodactylus), with notes on American pterosaurs. Field Mus. Publ. (Geological Ser.) 2(3):125–163, 2 figs., pls. XL-XLIV. However, in 1994, Christopher Bennett concluded that P. longiceps and another species called P. sternbergi would be the only valid Pteranodon species, while the other ones were either considered nomina dubia or synonyms.