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Jixiangornis
''Jixiangornis'' is a genus of primitive avialans from the Early Cretaceous. Like later avialans, it had no teeth, but it also had a long tail, unlike modern birds. Since teeth were still present in some more advanced short-tailed avialans, ''Jixiangornis'' seems to have evolved its toothlessness independently of modern birds. The long forelimb (131% of hindlimb length) indicates at least some aerial ability. ''Jixiangornis'' is currently known only from a single specimen, a complete but juvenile skeleton. The fossil was found in the Yixian Formation near Beipiao City, western Liaoning, China.
==Classification==
The only known species, ''J. orientalis'' ("Oriental bird from the Yixian Formation"), was described in November 2002. Ji ''et al.'' (2002) considered ''Jixiangornis'' capable of stronger flight than either ''Archaeopteryx'' or ''Jeholornis''. Their phylogenetic tree shows ''Jixiangornis'' forming a clade (called "Euavialae" by Ji ''et al.'') with birds that excludes ''Archaeopteryx'' and ''Jeholornis'' (=''Shenzhouraptor'').
An alternative view was presented by Zhou Zong-He and Zhang Fu-Cheng in 2006. They classified both ''Jixiangornis'' and ''Shenzhouraptor'' as junior synonyms of ''Jeholornis prima'', meaning that ''Jixiangornis'' cannot be more advanced than ''Shenzhouraptor''. This approach, however, was problematical given the numerous differences between ''Jixiangornis'' and ''Shenzhouraptor/Jeholornis'', and a phylogenetic analysis performed in 2014 found that it may actually be more closely related to short-tailed avialans (Pygostylia) than to ''Jeholornis'', as originally thought.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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