Jeholornis

Name: Jeholornis ‭(‬Jehol bird‭)‬.
Phonetic: Je-hol-or-niss.
Named By: Z.‭ ‬Zhou‭ & ‬F.‭ ‬Zhang‭ ‬-‭ ‬2002.
Synonyms: Shenzhouraptor,‭ ‬Jixiangornis.
Classification: Chordata,‭ ‬Aves,‭ ‬Jeholornithiformes,‭ ‬Jeholornithidae.
Species: J.‭ ‬prima‭ (‬type‭)‬,‭ ‬J.‭ ‬palmapenis.
Diet: Herbivore.
Size: Up to‭ ‬80‭ ‬centimetres long.
Known locations: China,‭ ‬Hebei Province‭ ‬-‭ ‬Jiufotang Formation,‭ ‬Liaoning Province‭ ‬-‭ ‬Yixian Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: Few individuals.

       Jeholornis was a primitive bird that is known from both the Hebei and Liaoning provinces of China where individuals of the genus lived during the early cretaceous.‭ ‬At eighty centimetres long from the tip of the snout to the tip of the tail,‭ ‬Jeholornis was quite a large bird for the time.‭ ‬Two additional bird genera named Shenzhouraptor and Jixiangornis‭ (‬also both named in‭ ‬2002‭) ‬are now regarded as synonyms to Jeholornis.‭ ‬There has been previous dispute over whether Shenzhouraptor should have priority over Jeholornis since they were both named so closely together with Shenzhouraptor appearing in a monthly journal and Jeholornis in a weekly one,‭ ‬but‭ ‬Jeholornis is usually treated as valid since in these circumstances weekly journals are seen to have technical priority.
       Jeholornis was similar to genera such as Epidexipteryx and Incisivosaurus‭ ‬since those individuals‭ ‬also‭ ‬had short but high skulls.‭ ‬The jaws curved downwards and depending upon the fossil specimen,‭ ‬show a greatly reduced amount of teeth.‭ ‬The holotype specimen only possessed three pairs of reduced blunt teeth in the lower jaw,‭ ‬while another suggests no teeth at all.‭ ‬These were likely feeding adaptations that allowed Jeholornis to pluck up and swallow seeds,‭ ‬something that can be supported by the discovery of around fifty,‭ ‬eight to ten millimetre seeds believed to be from the plant genus Carpolithes inside what was once the crop of a Jeholornis.
       Jeholornis had better developed wings than earlier bird forms such as Archaeopteryx,‭ ‬though they were still not as well adapted for true flapping flight as the wings of modern birds are.‭ ‬The wings were still longer than the legs,‭ ‬and the feathers were asymmetrical similar to modern birds.‭ ‬Like with many primitive forms,‭ ‬gliding flight would have certainly been possible for Jeholornis,‭ ‬but it is still unknown if it could use flapping flight since the arrangement of the shoulders would have still had a limited range of motion hindering a flight stroke where the wings passed above the back.
       Jeholornis still lacked a pygostyle and instead had a long more dinosaur-like tail.‭ ‬This feature would not have made flight impossible,‭ ‬but it would not have been as good as a pygostyle that supported the growth of flight feathers from the tail.‭ ‬Analysis of the bones of Jeholornis also indicate that individuals grew very slowly,‭ ‬another primitive trait shared with other early bird forms,‭ ‬though as the Cretaceous period went on birds would develop to become very fast growing animals.
       One of the key important things about Jeholornis is that the hallux‭ (‬first toe‭) ‬is partially reversed meaning that it was semi opposable.‭ ‬In modern birds the hallux is completely opposable to the other toes so that a bird can grip hold of branches,‭ ‬in a similar manner to how you can hold onto railings by wrapping your thumb and fingers around them.‭ ‬Jeholornis would not have been as capable of this as modern birds,‭ ‬but again more primitive forms such as Archaeopteryx lacked an opposable hallux all together and could not perch like modern birds at all.‭ ‬Therefore the hallux of Jeholornis shows the continuing transition to the modern bird form,‭ ‬helping to fill in another gap in the evolutionary theory of dinosaurs to birds.

Further reading
-‭ ‬A long-tailed,‭ ‬seed-eating bird from the Early Cretaceous of China.‭ ‬-‭ ‬Z.‭ ‬Zhou‭ & ‬F.‭ ‬Zhang‭ ‬-‭ ‬2002.
-‭ ‬A new species of Jeholornis with complete caudal integument.‭ ‬-‭ ‬Jingmai K.‭ ‬O'Connor,‭ ‬Chengkai Sun,‭ ‬Xing Xu,‭ ‬Xiaolin Wang and Zhonghe Zhou‭ ‬-‭ ‬2012.
-‭ ‬Jeholornis compared to Archaeopteryx,‭ ‬with a new understanding of the earliest avian evolution.‭ ‬-‭ ‬Z.‭ ‬-H.‭ ‬Zhou‭ & ‬F.‭ ‬-C Zhang‭ ‬-‭ ‬2003.
-‭ ‬P.‭ ‬Senter‭ ‬-‭ ‬Scapular orientation in theropods and basal birds,‭ ‬and the origin of flapping flight‭ ‬-‭ ‬2006.
-‭ ‬Reconstructing the habits of Jeholornis prima.‭ ‬-‭ ‬Z.‭ ‬Li‭ & ‬Y.‭ ‬Zhang‭ ‬-‭ ‬2008.
-‭ ‬A new specimen of a Jeholornis-like long-tailed bird shows that Jixiangornis is a junior synonym of Jeholornis prima.‭ ‬-‭ ‬X.‭ ‬Wang,‭ ‬G.‭ ‬Dyke‭ & ‬P.‭ ‬Godefroit‭ ‬-‭ ‬2012.



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