Name: Yixianornis ‭(‬Yixian bird‭)‬.
Phonetic: Yiks-e-an-or-niss.
Named By: X.‭ ‬Zhou‭ & ‬F.‭ ‬Zhang‭ ‬-‭ ‬2001.
Classification: Chordata,‭ ‬Aves,‭ ‬Yanornithiformes,‭ ‬Songlingornithidae.
Species: Y.‭ ‬grabaui‭ (‬type‭)‬.
Diet: Uncertain.
Size: About‭ ‬20‭ ‬centimetres long,‭ ‬40‭ ‬centimetre wingspan.
Known locations: China,‭ ‬Liaoning Province‭ ‬-‭ ‬Jiufotang Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: Complete individual preserved on a slab which includes clear impressions of the feathers.

       Yixianornis clearly differs from most other early Cretaceous birds in that the wings are rounded instead of pointed.‭ ‬The tail of Yixianornis‭ ‬is‭ ‬also clearly formed into a pygostyle which allowed for a strong and flexible attachment for tail feathers,‭ ‬which could be fanned out in flight,‭ ‬and then packed tight when resting.‭ ‬Altogether the form of the wings of Yixianornis indicate that this was a bird that was much closer to modern forms than other early Cretaceous birds such as Confuciusornis.‭ ‬The wings also indicate that Yixianornis was flying amongst densely overgrown areas such as forests where space was limited.‭ ‬By having short but broad wings,‭ ‬Yixianornis could avoid unnecessary damage to the wings from brushing against branches and tree trunks.‭ ‬Such wing proportions are still seen in modern birds that frequent forested habitats.
       Yixianornis was likely a strong flyer,‭ ‬with the hand bones fused together for greater strength during a flight stroke,‭ ‬while the breast bone has a strong keel allowing for the attachment of larger pectoral muscles,‭ ‬allowing for stronger prolonged flapping flight.‭ ‬Yixianornis still had some primitive feature however,‭ ‬the most obvious of which is the presence of small peg like teeth in the mouth.‭ ‬Most of these teeth seemed to have been packed to‭ ‬the rear of the mouth,‭ ‬particularly in the lower jaw,‭ ‬while the anterior‭ (‬front‭) ‬tips of the mouth are lacking any teeth but have pitting.‭ ‬This may indicate that Yixianornis had developed a rudimentary beak that covered the forward portion of the mouth.

Further reading
-‭ ‬Two new ornithurine birds from the Early Cretaceous of western Liaoning,‭ ‬China.‭ ‬-‭ ‬Chinese Science Bulletin‭ ‬46‭(‬15‭)‬:1258-1264.‭ ‬-‭ ‬X.‭ ‬Zhou‭ & ‬F.‭ ‬Zhang‭ ‬-‭ ‬2001.
-‭ ‬Insight into the evolution of avian flight from a new clade of Early Cretaceous ornithurines from China and the morphology of Yixianornis grabaui.‭ ‬-‭ ‬Journal of Anatomy,‭ ‬208‭(‬3‭)‬:‭ ‬287-308.‭ ‬-‭ ‬J.‭ ‬A.‭ ‬Clarke,‭ ‬Z.‭ ‬Zhou‭ & ‬F.‭ ‬Zhang‭ ‬-‭ ‬2006.


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