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. 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. A peculiar discovery was made in 1887 by Seeley in the Isle of Wight, an island off the coast of southern England. Seeley thought that these fossil remains belonged to bird-like creature, which he then named Ornithodesmus cluniculus. Seeley also reported another specimen found on the same site. Seeley named the new species O. latidens in 1901 based on this discovery, the specific name translates to "wide tooth". He presumably assigned this new species to Ornithodesmus due to synapomorphies between their sacra, but his conclusion was not entirely clear. In 1913, English paleontologist Reginald Walter Hooley reviewed O. latidens in detail, based on specimens he had found, and placed the genus Ornithodesmus within a newly created family, Ornithodesmidae. Later in 1993, the British paleontologists Stafford C. Howse and Andrew C. Milner concluded that the holotype sacrum and only specimen of the species O. cluniculus didn't belong to a pterosaur, but instead to a maniraptoran theropod dinosaur. They pointed out that no detailed attempts had been made to compare the sacrum of O. cluniculus with those of pterosaurs, and that the species O. latidens had in effect been treated as the type species of the genus Ornithodesmus in their conclusion. Now as a definite species of pterosaur, "O." latidens thus required a new generic name. In 2001, Howse, Milner, and David Martill, reassigned "O." latidens to a new genus called Istiodactylus, resulting in a new combination known as Istiodactylus latidens. The generic name Istiodactylus means "sail finger", in reference to its proportionally large wings. Classification Originally defined by Alexander Kellner in 1996, Pteranodontoidea is sometimes considered a synonym of the clade Ornithocheiroidea according to several studies. The name Ornithocheiroidea was originally defined as an apomorphy-based taxon by Christopher Bennett in 1994. In 2003 however, Kellner redefined Ornithocheiroidea to