Shenzhouraptor
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 life restoration of Shenzhouraptor
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| Shenzhouraptor sinensis Q. Ji, S. Ji, You, Zhang, Yuan, X. Ji, J. Li & Y. Li, 2002 |
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Shenzhouraptor sinensis[1] (or Jeholornis prima[2] Zhou & F. C. Zhang, 2002) is the name given to a genus of primitive bird found in the Early Cretaceous Yixian Formation of Hebei, China. It not fully resolved what the correct name of the taxon is, depending on whether Shenzhouraptor was published or merely announced two days before Jeholornis. Few, but fairly complete and well-preserved skeletal remains are known. Zhou & Zhang (2006) also classified the apparently more advanced contemporary genus Jixiangornis as junior synonym of Jeholornis; it remains to be seen which approach finds acceptance.
The skeletons are generally bird-like, but have long fingers, legs and long tails with distinct vertebrae. Altogether, they appear more birdlike than Archaeopteryx, but not very much so. The tail structure is even more dinosaurian, but wings, thorax and skull have distinctly more avian features. The flight apparatus was overall quite similar to that of Confucisornis in form and function.
Feather traces on the Shenzhouraptor specimen show that unlike Confuciusornis, it had rounded, broad wings like a chicken or goshawk. The tail of specimen IVPP V13350 bears at its end a bunch of bristle-like feathers like those found in Caudipteryx.
The stomach contents of the Jeholornis type were remains of seeds. It seems odd that the Jeholornis specimen, about three-quarters the size of the Shenzhouraptor, had small teeth, whereas the latter seems to have had a tootless beak like Jixiangornis. Assuming that early avians grew more slowly than modern birds and that the taxa are indeed conspecific, this would imply that a growing Shenzhouraptor would primarily catch small animals like insects and loose its teeth and shift to a diet of seets and fruits when fully grown. Two other specimens, IVPP V13353 and the aforementioned V13350 are smaller still and most certainly immature birds; they both have teeth.
A more trivial explanation would be that, given the state of preservation of the Shenzhouraptor type, the dentary on which the teeth are located in the smaller birds is missing or destroyed, and with it any teeth the larger bird may have had [1]. Moreover, as demonstrated by the toothed specimens, the number of teeth varied between individuals.
[edit] References
- Ji, Q.; Ji, S.; You, H.; Zhang, J.; Yuan, C.; Ji, X.; Li, J. & Li, Y (2002): [Discovery of an avialae bird - Shenzhouraptor sinensis gen. et sp. nov - from China]. Geol. Bull. Chin. 21(7): 363-369 + 2 plates [in Chinese with English abstract] PDF fulltext (English translation)
- Zhou Z.-H. & Zhang F.-C. (2002): A long-tailed, seed-eating bird from the Early Cretaceous of China. Nature 418: 405-409. DOI:10.1038/nature00930 (HTML abstract) Supplementary information
- Zhou Z.-H. & 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) PDF fulltext
- Zhou Z.-H. & Zhang F.-C. (2006): Mesozoic birds of China - A synoptic review. Vertebrata Palasiatica 44(1): 74-98. PDF fulltext
[edit] Footnotes
- ^ "Chinese Raptor from the 'Divine Land'"/approx. "Divine Raptor-bird from China"
- ^ "First bird from Jehol"
