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''Rahonavis'' is a genus of bird-like theropods from the Late Cretaceous (Maastrichtian, about 70 mya) of what is now northwestern Madagascar. It is known from a partial skeleton (UA 8656) found by Catherine Forster and colleagues in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province.〔Tudge, Colin (2009) ''The Bird:A Natural History of Who Birds Are, Where They Came From, and How They Live'' ()〕 ''Rahonavis'' was a small predator, at about long,〔Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'' (Supplementary Information )〕 with the typical ''Velociraptor''-like raised sickle claw on the second toe. The name ''Rahonavis'' means, approximately, "cloud menace bird", from Malagasy ' (RA-hoo-na, "cloud" or "menace") + Latin ''ラテン語:avis'' "bird". The specific name, ''R. ostromi'', was coined in honor of John Ostrom. ==Classification== ''Rahonavis'' has historically been the subject of some uncertainty as to its proper taxonomic position - whether it is a member of the clade Avialae (birds) or a closely related dromaeosaurid. The presence of quill knobs on its ulna (forearm bone) led initially to its inclusion as an avialan; however, the rest of the skeleton is rather typically dromaeosaurid in its attributes. Given the extremely close affinities between primitive birds and their dromaeosaurid cousins, along with the possibility that flight may have developed and been lost multiple times among these groups, it has been difficult to place ''Rahonavis'' firmly among or outside the birds. ''Rahonavis'' could be a close relative to ''Archaeopteryx'', as originally suggested by the describers, and thus a member of the clade Avialae, but while the pelvis shows adaptations to flight similar in function to those of ''Archaeopteryx'', they seem to be independently derived. Beginning in the early 2000s, a consensus emerged among most theropod researchers that ''Rahonavis'' was more closely related to deinonychosaurs than to avialans, and specifically was a member of the South American dromaeosaurid clade Unenlagiinae. A 2005 analysis by Makovicky and colleagues found ''Rahonavis'' to be closely related to the unenlagiines ''Unenlagia'' and ''Buitreraptor''.〔 (Supplementary information ).〕 Norell and colleagues (2006) also found ''Rahonavis'' to lie within the Unenlagiinae, as the sister taxon to ''Unenlagia'' itself. A 2007 study by Turner and colleagues again found it to be an unenlagiine dromaeosaurid, closely related to ''Unenlagia''. This consensus has been challenged, however, by a few studies published since 2009 that have found many traditional "dromaeosaurids", including the unenlagiines, closer to Avialae than to dromaeosaurines. A large analysis published by Agnolín and Novas in 2013, for example, recovered ''Rahonavis'' as closer to Avialae than to Dromaeosauridae. That study found ''Rahonavis'' in particular to be closer to birds than either unenlagiines or dromaeosaurids.〔Agnolín, F.L. and Novas, F.E. (2013). "Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, ''Anchiornis'' and Scansoriopterygidae". ''SpringerBriefs in Earth System Sciences'': 1–96.〕 The discoverers of ''Rahonavis'' initially named it ''Rahona'' but changed the name after discovering that the name ''Rahona'' was already assigned to a genus of lymantriid moths. 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「Rahonavis」の詳細全文を読む スポンサード リンク
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