Criorhynchus

''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 and possibly Morocco.

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, though a specimen referred to ''O.'' cf. ''simus'' is also known from Morocco.

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''.

Discovery and naming

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.Unwin D.M., 2001, "An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England", ''Mitteilungen aus dem Museum für Naturkunde in Berlin'', Geowissenschaftliche Reihe 4: 189–221

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'' (meaning "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. Between the years 1869 and 1870, Seeley 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. tenuirostris'', ''O. machaerorhynchus'', ''O. platystomus'', ''O. microdon'', ''O. oweni'' and ''O. huxleyi'', thus 27 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, Sir 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. In 1874, he created two new genera: '' Coloborhynchus'' and ''Criorhynchus''. ''Coloborhynchus'' (meaning "maimed beak") which comprised a new type species called ''Coloborhynchus clavirostris'', as well as two other species reassigned from ''Ornithocheirus'': ''C. sedgwickii'' and ''C. cuvieri''. ''Criorhynchus'' (meaning "ram beak") consisted entirely of former ''Ornithocheirus'' species: the type species, ''Criorhynchus simus'', and furthermore such as ''C. eurygnathus'', ''C. capito'', ''C. platystomus'', ''C. crassidens'' and ''C. reedi''.

Seeley did not accept Owen's position. In 1881 he designated ''O. simus'' the type species of ''Ornithocheirus'' and named a new separate species called '' O. bunzeli''. In 1888, Edwin Tulley Newton reassigned several existing species names into ''Ornithocheirus'', which created new combinations: ''O. clavirostris'', ''O. daviesii'', ''O. sagittirostris'', ''O. validus'', ''O. giganteus'', '' O. clifti'', ''O. diomedeus'', ''O. nobilis'', ''O. curtus'', ''O. macrorhinus'' and ''O. hlavaci''. He also reassigned the species ''O. umbrosus'' and ''O. harpyia'' into ''Ornithocheirus'', which were formerly species given to the genus ''Pteranodon'' by Edward Drinker Cope back in 1872.

In 1914 Reginald Walter Hooley made a new attempt to structure the large number of species. Hooley synonymized Owen's ''Criorhynchus'' to ''Ornithocheirus'', in which he also sunk ''Coloborhynchus'' into that genus, meaning that the only generic name he kept was ''Ornithocheirus''. To allow for a greater differentiation, Hooley created two new genera, again based on jaw form: '' Lonchodectes'' and '' Amblydectes''. The genus ''Lonchodectes'' (meaning "lance biter") consisted of the former species ''Pterodactylus compressirostris'', and ''Pterodactylus giganteus'', which were reassigned as ''Lonchodectes compressirostris'', the type species, and ''Lonchodectes giganteus'', in addition, Hooley also named a new separate species called ''L. daviesii''. The genus ''Amblydectes'' (meaning "blunt biter") also consisted of three species: ''A. platystomus'', ''A. crassidens'' and ''A. eurygnathus''. Hooley's classification however, was rarely applied later in the century, and therefore paleontologists weren't aware of it, and kept subsuming all the poorly preserved and confusing material under the name ''Ornithocheirus''. In 1964, a Russian-language overview of Pterosauria designated the species ''Lonchodectes compressirostris'', which was identified as ''Pterodactylus compressirostris'' in the overview, as the type species of ''Ornithocheirus'', which was then followed by Kuhn in 1967, and Wellnhofer in 1978, yet those authors weren't aware that back in 1881, Seeley made already made the species ''P. simus'' as the type species of ''Ornithocheirus'', in which defined the new combination of ''O. simus''.

From the seventies onwards many new pterosaur fossils were found in Brazil in deposits slightly older than the Cambridge Greensand, 110 million years old. Unlike the English material, these new finds included some of the best preserved large pterosaur skeletons and several new genera names were given to them, such as '' Anhanguera''. This situation caused a renewed interest in the ''Ornithocheirus'' material and the validity of the several names based on it, for it might be possible that it could by more detailed studies be established that the Brazilian pterosaurs were actually junior synonyms of the European types. Several European researchers concluded that this was indeed the case. Unwin revived ''Coloborhynchus'' and Michael Fastnacht ''Criorhynchus'', each author ascribing Brazilian species to these genera. However, in 2000 Unwin stated that ''Criorhynchus'' could not be valid. Referring to Seeley's designation of 1881 he considered ''Ornithocheirus simus'', holotype CAMSM B.54428, to be the type species. This also made it possible to revive ''Lonchodectes'', using as type the former ''O. compressirostris'', which then became ''L. compressirostris''.

As a result, though over forty species have been named in the genus ''Ornithocheirus'' over the years, only ''O. simus'' is currently considered valid by all pterosaur researchers. The species ''Tropeognathus mesembrinus'', which was named by Peter Wellnhofer in 1987, was assigned to ''Ornithocheirus'' by David Unwin in 2003, making ''Tropeognathus'' a junior synonym. In 1989 however, Alexander Kellner considered it as an ''Anhanguera mesembrinus'', then as a ''Coloborhynchus mesembrinus'' by André Veldmeijer in 1998 and as a ''Criorhynchus mesembrinus'' by Michael Fastnacht in 2001. Even earlier, in 2001, Unwin had referred the "Tropeognathus" material to ''O. simus'' in which was followed by Veldmeijer; however, Veldmeijer rejected ''O. simus'' as the type species in favor of ''O. compressirostris'' (alternately ''Lonchodectes''), and he used the names ''Criorhynchus simus'' and ''Criorhynchus mesembrinus'' instead.Veldmeijer, A.J. (2006).
Toothed pterosaurs from the Santana Formation (Cretaceous; Aptian-Albian) of northeastern Brazil. A reappraisal on the basis of newly described material
." Tekst. – Proefschrift Universiteit Utrecht.

Formerly assigned species

In 2013, Rodrigues and Kellner found ''Ornithocheirus'' to be monotypic, containing only ''O. simus'', and placed most other species in other genera, or declared them ''nomina dubia''. They also considered ''O. platyrhinus'' a junior synonym of ''O. simus''.

Misassigned species:
*''O. compressirostris'' (Hooley, 1914) = ''Pterodactylus compressirostris'' Owen, 1851 Lonchodectes''">ow classified as '' Lonchodectes''/small>
*''O. crassidens'' Seeley, 1870 = Amblydectes''">ow classified as '' Amblydectes''/small>
*''O. cuvieri'' (Seeley, 1870) = ''Pterodactylus cuvieri'' Bowerbank, 1851 ow classified as ''Cimoliopterus''">Cimoliopterus.html" ;"title="ow classified as ''Cimoliopterus">ow classified as ''Cimoliopterus''/small>
*''O. curtus'' (Hooley, 1914) = '' Pterodactylus curtus'' Owen, 1874
*''O. giganteus'' (Owen, 1879) = ''Pterodactylus giganteus'' Bowerbank, 1846 [now classified as ''Lonchodraco'']
*"O." ''hilsensis'' Koken, 1883 = indeterminate Neotheropoda
*''O. mesembrinus'' (Peter Wellnhofer, Wellnhofer, 1987) = '' Tropeognathus mesembrinus'' Wellnfofer, 1987
*''O. nobilis'' (Owen, 1869) = ''Pterodactylus nobilis'' Owen 1869
*''O. sagittirostris'' (Seeley, 1874) ow classified as ''Serradraco''
*''O. simus'' (Richard Owen">Owen