View source for Biology:Zhongornis

{{Short description|Extinct genus of bird-like animals}}
{{Italic title}}
{{speciesbox
| fossil_range = [[Earth:Early Cretaceous|Early Cretaceous]], {{fossilrange|122}}
| genus = Zhongornis 
| parent_authority = Gao ''et al.'', 2008
| species = haoae
| authority = Gao ''et al.'', 2008
| display_parents = 2
}}

'''''Zhongornis''''' (meaning "intermediate bird"<ref name=basalbird2010>Li, D.; Sulliven, C.; Zhou, Z; Zhang, Z. (2010). "Basal birds from China: a brief review." ''Chinese Birds'', '''1'''(2): 83-96 {{doi|10.5122/cbirds.2010.0002}}</ref>) is a genus of primitive avialan that lived during the Early Cretaceous. It was found in rocks of the [[Earth:Yixian Formation|Yixian Formation]] in Lingyuan City ({{wipe|China}}), and described by Gao et al. in 2008.<ref name="Gaoetal2008">Gao, Cunling; Chiappe, L.M.; Meng, Q.; O'Connor, J.K.; Wang, X.; Cheng, X.; Liu, J. (2008) "A New Basal Lineage Of Early Cretaceous Birds From China And Its Implications On The Evolution Of The Avian Tail." "Palaeontology" Vol. 51, Part 4, pp. 775-791. {{doi|10.1111/j.1475-4983.2008.00793.x}}</ref>

''Zhongornis'' has only one described species, ''Zhongornis haoae''. The only specimen is a fossil slab and counterslab numbered D2455/6. It is in the collection of the Dalian Natural History Museum. It is a fairly complete skeleton about eight centimeters in length. Pores in the bones and unfused sutures in the skeleton indicate that the specimen was a juvenile, but the authors believe that it was developed enough to erect a new [[Biology:Taxon|taxon]] on the basis of its unique morphological characters. There are feather impressions preserved on the right hand and also probable tail feathers preserved near the left foot. ''Zhongornis'' had a beaked mouth with no teeth. The tail is proportionately short, has thirteen vertebrae, and no pygostyle. The third finger has only two phalangeal bones, unlike non-avian dinosaurs and ''[[Biology:Confuciusornis|Confuciusornis]]'', and more like [[Biology:Enantiornithes|Enantiornithes]] and more advanced avialans. These features and a cladistic analysis indicate that ''Zhongornis'' is the sister group to all [[Biology:Pygostylia|pygostylia]], meaning that it is intermediate between long-tailed Avialae, like ''[[Biology:Archaeopteryx|Archaeopteryx]]'', and more advanced taxa, like ''Confuciusornis''.

==Evolutionary significance==
''Zhongornis'' provides important anatomical information about the evolutionary transition from primitive basal Avialae like ''Archaeopteryx'', which had a long bony tail and a dinosaur-like third finger, to the more advanced avialans like the [[Biology:Enantiornithes|Enantiornithes]], which had reduced third fingers and tails fused into rigid [[Biology:Pygostyle|pygostyle]]s. ''Zhonghornis'' is the only fossil ever found that seems to be intermediate in these features. It appears to have one less bone in the third finger than ''Archaeopteryx'', and one more than ''[[Biology:Longipteryx|Longipteryx]]'', suggesting that it is an intermediate between the two.<ref name="Gaoetal2008"/> ''Zhongornis'' also seems to be intermediate in its tail anatomy. It has only thirteen caudal vertebrae, far less than the 22 in ''Archaeopteryx''. None of the vertebral centra are fused, but the last four do form a continuous lateral flange, implying that this specimen had an incipient pygostyle. Previous to this fossil Sanz et al. (1992) suggested that the evolution of the pygostyle may have proceeded as the numerous vertebrae of the tail became very small and highly ankylosed.<ref name="Sanzetal1992">Sanz, J.L., Bonaparte, J.F. (1992) A New Order of Birds (Class Aves) From the Lower Cretaceous of Spain. Bulletin of the Natural History Museum of Los Angeles, Science Series. 36, 39-49.</ref> ''Zhongornis'' suggests that shortening of the tail, and a large reduction in the number of vertebrae, preceded the origin of the pygostyle in the evolution of at least one bird language.

==Other interpretations==
After a detailed restudy, O'Connor and Sullivan suggest that this juvenile bird from the Early Cretaceous Jehol fauna of China actually possesses 20, rather than 14, tail vertebrae; further, this tail is very similar to those of ''Epidexipteryx'' (a scansoriopterygid) and ''[[Biology:Caudipteryx|Caudipteryx]]'' (an oviraptorosaur). Based on this and other features, the authors reinterpreted ''Zhongornis'' as the sister taxon of scansoriopterygids, and further suggested that this clade (''Zhongornis'' + ''Scansoriopterygidae'') is the sister group of [[Biology:Oviraptorosauria|Oviraptorosauria]].<ref>{{cite journal|last1=O'Connor|first1=Jingmai K|last2=Sullivan|first2=Corwin|date=January 2014|title=Reinterpretation of the Early Cretaceous maniraptoran (Dinosauria: Theropoda) ''Zhongornis haoae'' as a scansoriopterygid-like non-avian, and morphological resemblances between scansoriopterygids and basal oviraptorosaurs|url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/201401/P020140121386966325113.pdf|journal=Vertebrata PalAsiatica|volume=52|issue=1|pages=3–30}}</ref> Other phylogenetic analyses, including a larger dataset, don't consider the hypothesis that ''Zhongornis'' is a scansoriopterygid, instead finding it in its traditional position as a primitive relative of pygostylians, or as a close relative of ''Confuciusornis''.<ref name=cauetal2015>{{cite journal|doi=10.7717/peerj.1032|pmid=26157616|pmc=4476167|title=The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod ''Balaur'' bondoc(Dinosauria, Maniraptora): Dromaeosaurid or flightless bird?|journal=PeerJ|volume=3|pages=e1032|year=2015|last1=Cau|first1=Andrea|last2=Brougham|first2=Tom|last3=Naish|first3=Darren |doi-access=free }}</ref>

==References==
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[[Category:Early Cretaceous birds of Asia]]

{{Sourceattribution|Zhongornis}}