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Megaraptora is a group of large carnivorous theropod dinosaurs with controversial relationships. Phylogenetic studies conducted by Benson, Carrano and Brusatte (2010) and Carrano, Benson and Sampson (2012) recovered the group as a branch of the allosauroids (specifically within the family Neovenatoridae), part of a large group of carnosaurs that also includes the metriacanthosaurids, carcharodontosaurids, and allosaurids. This would make megaraptorans the last surviving allosauroids; at least a few megaraptorans, including ''Orkoraptor'', lived near the end of the Mesozoic era, dating to the late Santonian stage of the late Cretaceous period, about 84 million years ago. On the other hand, Novas ''et al.'' (2012), while confirming that ''Neovenator'' was closely related to carcharodontosaurids, simultaneously found ''Megaraptor'' and related genera to probably be coelurosaurs closely related to tyrannosaurids. A juvenile specimen of ''Megaraptor'' suggests it to be within Tyrannosauroidea, as well. From these debated relations, megaraptorans have been, at the moment, simply placed by some under avetheropods, mostly to remain neutral between carnosaurs and coelurosaurs. Though it is unknown as of yet where they stand in relation to other theropods, the origins of megaraptorids have recently been determined. Studies by paleontologists Phil Bell, Steve Salisbury et al of a newly discovered, as-yet-unnamed megaraptorid (referred to by the public media as "Lightning Claw") from opal fields southwest of Lightning Ridge, Australia, dating back 110 million years ago reveals that megaraptorids likely evolved in Australia, then spread to the rest of Gondwana in an episode of evolutionary radiation. The specimen also allowed for alternative phylogenitic testing as to the placement of megaraptorans as either tyrannosauroids or carcharodontosaurids.〔Bell, P. R., Cau, A., Fanti, F., & Smith, E. (2015). (A large-clawed theropod (Dinosauria: Tetanurae) from the Lower Cretaceous of Australia and the Gondwanan origin of megaraptorid theropods ). ''Gondwana Research''.〕〔(New dinosaur is Australia’s largest carnivore ) ''Australian Geographic''.〕 ==Classification== The cladogram below follows the 2010 analysis by Benson, Carrano and Brusatte.〔 Another study published later in 2010 found the Australian theropod ''Rapator'' to be a megaraptoran extremely similar to ''Australovenator'', and the description of ''Siats'' also recovered it as a megaraptoran. }} }} }} This cladogram shown below follows an analysis by Porfiri et al., 2014, which recovers ''Eotyrannus'' as a megaraptoran; 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「Megaraptora」の詳細全文を読む スポンサード リンク
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