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Paraprotopteryx
''Paraprotopteryx'' is a genus of enantiornithine birds.〔Zheng, X. Zhang, Z. & Hou, L. (2007) A new enantiornithine bird with four long rectrices from the Early Cretaceous of northern Hebei, China. ''Acta Geologica Sinica'' 81(5):703-708.〕 Though initially reported to be from the Early Cretaceous Yixian Formation, later investigation showed the fossil actually came from the Qiaotou member of the Huajiying Formation of Fengning, Hebei Province, China, and is therefore of uncertain age. While much of the Huajiying Formation underlies the Yixian Formation,〔Jin, Zhang, Li, Zhang, Li and Zhou (2008). "On the horizon of ''Protopteryx'' and the early vertebrate fossil assemblages of the Jehol Biota." ''Chinese Science Bulletin'', 53(18): 2820-2827.〕 Ji and colleagues suggested in 2008 that the Qiaotou Member correlates with the Dawangzhangzi bed of the Yixian Formation, dated to ~122 Ma ago by Zhou in 2006.〔Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." ''Geological Journal'', 41: 377–393.〕
== Distinguishing Characteristics ==
''Paraprotopteryx'' has a furcula (wishbone) which is shaped like a Y with a narrow angle between the clavicles. It also has an unusually shaped breastbone, distinguishing it from other birds in its suborder, the enantiornithines. The carpometacarpus is only partially fused.
It has four long rectrices (flight feathers on the tail), which may represent an important step in feather evolution. For comparison, most modern birds have twelve rectrices; grouse often have more than twelve, while grebes have none. In ''Paraprotopteryx'' they may have served as a secondary sex characteristic. However, although the presence of two ribbon-like rectrices is certain (as in the related enantiornithine bird ''Protopteryx'') there is a suspicion that the second pair of rectrices might be the result of artifice. 〔Jingmai K. O’Connor, Luis M. Chiappe, Cheng-ming Chuong, David J. Bottjer and Hailu You (2012) "Homology and Potential Cellular and Molecular Mechanisms for the Development of Unique Feather Morphologies in Early Birds." ''Geosciences'', 2 157-177.〕
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