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''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 late Cretaceous period, about 110 million years ago.〔Vullo, R. and Neraudeau, D. (2009). "Pterosaur Remains from the Cenomanian (Late Cretaceous) Paralic Deposits of Charentes, Western France." ''Journal of Vertebrate Paleontology'', 29(1):277–282. 〕 Additional fossils from the Santana Formation of Brazil, dating to 112–108 million years ago, are sometimes classified as species of ''Ornithocheirus'', but have also been placed in their own genera, most notably ''Tropeognathus''. ==Description== The original material of ''Ornithocheirus simus'', recovered from England, indicates a mid-sized species with a wing span of 2.5 m (8.2 ft). Referred specimens attributed to ''Ornithocheirus simus'' can reach 5 m (16.5 ft). ''O. simus'' bore a distinctive convex "keeled" crest on its snout.〔Fastnacht, M. (2001). "First record of Coloborhynchus (Pterosauria) from the Santana Formation (Lower Cretaceous) of the Chapada do Araripe of Brazil." ''Paläontologisches Zeitschrift'', 75: 23–36.〕 Unlike the related ''Anhanguera'' and ''Coloborhynchus'', which had an expanded rosette of teeth at the jaw tips, ''Ornithocheirus'' species (including ''O. simus'') had straight jaws that narrowed toward the tip. Also unlike related pterosaurs, the teeth of ''Ornithocheirus'' were mostly vertical, rather than set at an outward-pointing angle. They also had fewer teeth than related species.〔 The type specimen of ''Ornithocheirus simus'' is represented only by a broken piece of the upper jaw tip. While it does preserve several characteristic features of ''Ornithocheirus'', it is nearly identical to comparable bones in ''Tropeognathus mesembrinus'', making clear distinction between these two species impossible.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ornithocheirus」の詳細全文を読む スポンサード リンク
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