Ornithocheirus

Ornithocheirus (from Ancient Greek 'ὄρνις', meaning bird, and 'χεῖρ', meaning hand) is a pterosaur genus known from fragmentary fossil remains uncovered from sediments in the UK. Several species have been referred to the genus, most of which are now considered as dubious species, or members of different genera, and the genus is now often considered to include only the type species, Ornithocheirus simus. Species have been referred to Ornithocheirus from the mid-Cretaceous period of both Europe and South America, but O. simus is known only from the UK. Because O. simus was originally named based on poorly preserved fossil material, the genus Ornithocheirus has suffered enduring problems of zoological nomenclature. Fossil remains of Ornithocheirus have been recovered mainly from the Cambridge Greensand of England, dating to the beginning of the Albian stage of the early Cretaceous period, about 110 million years ago. Additional fossils from the Santana Formation of Brazil are sometimes classified as species of Ornithocheirus, but have also been placed in their own genera, most notably Tropeognathus. O. simus is only known from fragmentary jaw tips. It bore a distinctive convex 'keeled' crest on its snout. Ornithocheirus had relatively narrow jaw tips compared to Anhanguera and Coloborhynchus, which had prominently-expanded rosettes of teeth. Also unlike related pterosaurs, the teeth of Ornithocheirus were mostly vertical, rather than set at an outward-pointing angle. It was believed in the past that Ornithocheirus was one of the largest pterosaurs to have existed, with a wingspan possibly measuring 40 feet wide. However, this is a highly exaggerated number, as the animal's wingspan likely measured 15 to 20 feet wide, which would make it a medium-sized pterosaur. A related species called Tropeognathus had a wingspan measuring between 20 to 25 feet wide. During the 19th century, in England many fragmentary pterosaur fossils were found in the Cambridge Greensand, a layer from the early Cretaceous, that had originated as a sandy seabed. Decomposing pterosaur cadavers, floating on the sea surface, had gradually lost individual bones that sank to the bottom of the sea. Water currents then moved the bones around, eroding and polishing them, until they were at last covered by more sand and fossilised. Even the largest of these remains were damaged and difficult to interpret. They had been assigned to the genus Pterodactylus, as was common for any pterosaur species described in the early and middle 19th century. Young researcher Harry Govier Seeley was commissioned to bring order to the pterosaur collection of the Sedgwick Museum in Cambridge. He soon concluded that it was best to create a new genus for the Cambridge Greensand material that he named Ornithocheirus, 'bird hand', as he in this period still considered pterosaurs to be the direct ancestors of birds, and assumed the hand of the genus to represent a transitional stage in the evolution towards the bird hand. To distinguish the best pieces in the collection, and partly because they had already been described as species by other scientists, he in 1869 and 1870 each gave them a separate species name: O. simus, O. woodwardi, O. oxyrhinus, O. carteri, O. platyrhinus, O. sedgwickii, O. crassidens, O. capito, O. eurygnathus, O. reedi, O. cuvieri, O. scaphorhynchus, O. brachyrhinus, O. colorhinus, O. dentatus, O. denticulatus, O. enchorhynchus, O. xyphorhynchus, O. fittoni, O. nasutus, O. polyodon, O. compressirostris, O. tenuirostris, O. machaerorhynchus, O. platystomus, O. microdon, O. oweni and O. huxleyi, thus 28 in total. As yet Seeley did not designate a type species. When Seeley published his conclusions in his 1870 book The Ornithosauria, this provoked a reaction by the leading British paleontologist of his day, Richard Owen. Owen was not an evolutionist and he therefore considered the name Ornithocheirus to be inappropriate; he also thought it was possible to distinguish two main types within the material, based on differences in snout form and tooth position — the best fossils consisted of jaw fragments. He in 1874 created two new genera: Coloborhynchus and Criorhynchus. Coloborhynchus, 'maimed beak', comprised a new species, Coloborhynchus clavirostris, the type species, and two species reassigned from Ornithocheirus: C. sedgwickii and C. cuvieri. Criorhynchus, 'ram beak', consisted entirely of former Ornithocheirus species: the type species Criorhynchus simus and furthermore C. eurygnathus, C. capito, C. platystomus, C. crassidens and C. reedi.