Jeholornis

Taxobox
name = "Jeholornis"
fossil_range = Early Cretaceous

---

image_width = 250px
image_caption = Life restoration of "Jeholornis" .
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Jeholornithiformes
familia = Jeholornithidae
genus = "Jeholornis"
genus_authority = Ji "et al.", 2002
subdivision_ranks=Species
subdivision=
*"J. prima" Ji "et al.", 2002 (type)
synonyms = "See text."

"Jeholornis" is a genus of Mesozoic bird that lived approximately 120 million years ago during the Early Cretaceous of China. Fossils of "Jeholornis" were discovered in the Jiufotang Formation in Hebei, China.

After "Archaeopteryx" and possibly "Rahonavis", "Jeholornis" is the most primitive known bird. "Jeholornis" had a long tail and a few small teeth, and was approximately the size of a turkey, making it one of the largest birds known until the Late Cretaceous.

The names "Shenzhouraptor sinensis" and "Jixiangornis orientalis" were formally made junior synonyms of "Jeholornis prima" by Zhou and Zhang in 2006.Zhou Z.-H. & Zhang F.-C. (2006). "Mesozoic birds of China - A synoptic review." "Vertebrata Palasiatica", 44(1): 74-98.]

Description

A few fairly complete and well-preserved skeletal remains are known. The type specimen is in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. It is cataloged as IVPP V13274. It was reported in the journal Nature in 2002. Two more specimens were later accessioned by the IVPP as V 13550 and V 13553 and they were reported in the journal Naturwissenschaften in 2003. Another specimen is in the collection of the Liaoning Provincial Museum of Paleontology, and is cataloged as LPM 0193 it was reported as "Shenzhouraptor" in the journal The Geological Bulletin of China in 2002. Another specimen was reported as"Jixiangornis" in the Journal of Nanjing University (Natural Sciences). Ji, Q. Ji, S. A., Zhang, H. B. (2002) "A new avialan bird - jixiangornis orientalis gen. et sp. nov. - from the Lower Cretaceous of Western Liaoning." Journal of Nanjing University (Nat Sci) 38(6):723-736]

The skeletons are generally similar to Archaeopteryx, but the tail structure is more like that of a dromaeosaur, and the coracoids are longer, more derived, and probably allowed for better flight capability. The flight apparatus skeleton was overall quite similar to that of "Confuciusornis" in form and function.Zhou, Z.-H., and Zhang, F.-C. (2003). "Jeholornis" compared to "Archaeopteryx", with a new understanding of the earliest avian evolution." "Naturwissenschaften", 90(5): 220-225. DOI|10.1007/s00114-003-0416-5 (HTML abstract)]

Feather traces on LPM 0193 show that unlike "Confuciusornis", it had rounded, broad wings like a chicken or goshawk.Fact|date=July 2008 The wing feathers were asymmetrical (as in modern flying birds) and up to 21 centimeters long, longer than than the forearm and hand combined.

The tail of several specimens preserve feathers at the end of the tail, shorter than those on the forelimbs. The construction of the tail was more solid than the tail of "Archaeopteryx", more similar to the tails of dromaeosaurs. Additionally, the feathers of the tail are arranged in a fan stemming from the tip, as in dromaeosaurs but unlike the tail feathers of "Archaeopteryx", which extend down the length of the tail. The tail of "Jeholornis" is also longer than that of "Archaeopteryx", and is made up up up to 27 vertebrae in "Jeholornis" compared with 23 vertebrae in "Archaeopteryx".

Classification and synonyms

"Jeholornis" contains only the type species, "Jeholornis prima" (meaning "first Jehol bird", in reference to the Jehol group of fossil beds where it was found, and the primitive appearance of the tail).Zhou, Z.-H. and Zhang, F.-C. (2002). "A long-tailed, seed-eating bird from the Early Cretaceous of China." "Nature", 418(6896): 405-409. DOI|10.1038/nature00930 (HTML abstract) [http://www.nature.com/nature/journal/v418/n6896/suppinfo/nature00930.html Supplementary information] ] . "Shenzhouraptor sinensis" (the name of which is derived from "Shenzhou", an ancient name for China, "raptor", Latin for "violent plunder"Ji, Q., Ji, S., You, H., Zhang, J., Yuan, C., Ji, X., Li, J. and Li, Y (2002). " [Discovery of an avialae bird - "Shenzhouraptor sinensis" gen. et sp. nov - from China] ." "Geological Bulletin of China", 21(7): 363-369 + 2 plates [in Chinese with English abstract] . [http://ravenel.si.edu/paleo/paleoglot/files/Ji&_02.pdf PDF fulltext (English translation)] ] ) was described in a journal later the same month. Two of the diagnostic characteristics which could have distinguished the genus from "Jeholornis" are size and the absence of teeth, which may be attributed to age and preservation bias. The other major difference was a different number of caudal vertebrae, though Zhou and Zhang showed in 2003 that the specimen was missing several of the proximal caudals.cite journal |last= Chiappe|first= Luis M.|authorlink= |coauthors=Dyke, Gareth J.|year= 2006|month= |title=The Early Evolutionary History of Birds|journal=Journal of the Paleontological Society of Korea|volume= 22|issue= 1|pages= 133–151|id= |url= |accessdate= |quote= ] In a 2006 study they also classified "Jixiangornis" as junior synonym of "Jeholornis";Zhou Z.-H. & Zhang F.-C. (2006). "Mesozoic birds of China - A synoptic review." "Vertebrata Palasiatica", 44(1): 74-98.]

Zhou and Zhang went on to classify "Jeholornis" in a new family, Jeholornithidae, of which it is the type genus, and the order Jeholornithiformes. No phylogenetic definitions for these groups were provided.

Paleobiology

The type fossil of "Jeholornis" preserves seeds in the area of the crop. The seeds belong to the conifer plant genus "Carpolithus", though it is uncertain exactly what type of plant this represents. The "Jeholornis" specimen, while about three-quarters the size of the "Shenzhouraptor", had small teeth in the upper jaw, whereas no teeth were visible in the latter. Two other specimens, IVPP V13353 and the aforementioned V13350 are smaller still and most certainly immature birds; they both have teeth. In the "Shenzhouraptor" type, the dentary and anterior skull are poorly preserved and this makes it impossible to say whether there were any teeth . The jaw is deep, the dentaries are well fused, and the teeth are reduced, and all indicate a specialized seed - feeding habit for "Jeholornis".

References

External links

* [http://www.dinodata.org/index.php?option=com_content&task=view&id=7453&Itemid=67 "Shenzhouraptor" at DinoData]