Sinornithosaurus

Name: Sinornithosaurus ‭(‬Chinese bird lizard‭)‬.
Phonetic: Sine-or-nith-oh-sore-s.
Named By: Xu,‭ ‬Wang‭ & ‬Wu‭ ‬-‭ ‬1999.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Theropoda,‭ ‬Dromaeosauridae,‭ ‬Microraptoria,‭ ‬Microraptorinae.
Species: S.millenii‭ (‬type‭)‬,‭ ‬S.‭ ‬haoiana.
Type: Carnivore.
Size: Around 120 ‬centimetres long.
Known locations: China,‭ ‬Liaoning Province‭ ‬-‭ ‬Yixian Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: 2‭ ‬specimens,‭ ‬with some other specimens possibly being examples of the genus.

       Sinornithosaurus was especially well preserved,‭ ‬and not only were the presence of feathers clearly revealed‭; ‬they showed indications of having differing colours for different body areas.‭ ‬The feathers,‭ ‬while not exactly like those of modern birds,‭ ‬are still more advanced than in other species,‭ ‬including some of the later dromaeosaurids.‭ ‬This is significant as it helps cement the argument that birds evolved from dinosaurs,‭ ‬but not from the later and larger dromaesarids,‭ ‬which detractors to the theory say is impossible.‭ ‬Instead it proves that the transition happened earlier with smaller dinosaurs that possibly also led arboreal lifestyles.
       As a living creature,‭ ‬Sinornithosaurus probably hunted around the forest floor looking for things like small mammals.‭ ‬Very interestingly the scleral rings indicate a cathermal lifestyle,‭ ‬meaning that Sinornithosaurus would have been active for small periods throughout the day or night.‭ ‬Aside from the usual night or day scenario,‭ ‬this would be good advantage for a forest hunter as light levels would be constantly changing as it moved through varying vegetation densities in the forest.
       Sinornithosaurus once had the suggestion put forward that it had a venomous bite.‭ ‬This was based on an interpretation of the front teeth being elongated and grooved to allow poison to run through,‭ ‬with space for poison glands in the skull.‭ ‬However a subsequent study has cast significant doubts against this theory on the basis that grooved teeth are known throughout all theropods,‭ ‬and are not indicative of poison delivery.‭ ‬The study also explained the elongated teeth simply as regular sized teeth that had partially fallen out as a result of the skull being crushed during the preservation process.‭ ‬No evidence was found to support the presence of poison glands on the basis that all the internal skull areas were as expected to be,‭ ‬with no special area for glands.

Further reading
- Cretaceous age for the feathered dinosaurs of Liaoning, China. - Nature 400:58-61 1 July 1999. - Carl C. Swisher, Yuan-qing Wang, Xiao-lin Wang, Xing Xu & Yuan Wang - 1999.
- A dromaeosaurid dinosaur with a filamentous integument from the Yixian Formation of China. - Nature" 401:262-266. - Xing Xu, Xiao-Lin Wang & Xiao-chun Wu - 1999.
- Branched integumental structures in Sinornithosaurus and the origin of feathers. - Nature 410 (6825): 200–204. - X. Xu, Z. Zhou & R. O. Prum - 2001.
- The distribution of integumentary structures in a feathered dinosaur. - Nature 410(6832) 1084-1087. - Q. Ji, M. A. Norell, K. Q. Gao, S. -A. Ji & D. Ren - 2001.
- Restudy on a small dromaeosaurid dinosaur with feathers over its entire body. - Earth Science Frontiers 9 (3): 57–63. - Q. Ji, S. -A. Ji, C. -X. Yuan, X. -X. Ji - 2002.
- A new species of dromaeosaurids from the Yixian Formation of western Liaoning. - Geological Bulletin of China. 23 (8): 778–783. - J. Liu, S. Ji, F. Tang & C. Gao - 2004.
- The birdlike raptor Sinornithosaurus was venomous. - Proceedings of the National Academy of Sciences. - E. Gong, L. D. Martin, D. E. Burnham & A. R. Falk - 2009.
- Evidence for a venomous Sinornithosaurus. - Paläontologische Zeitschrift - E. Gong, L. D. Martin, D. A. Burnham, A. R. Falk - 2010.
- A reassessment of the purported venom delivery system of the bird-like raptor Sinornithosaurus. - Paläontologische Zeitschrift - F. A. Gianechini, F. L. Agnolin & M. D. Ezcurra - 2010.
- Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds - Nature 463(7284), p. 1075. - Funcheng Zhang, Stuart L. Kearns, Patrick J. Orr, Michael J. Benton, Zhonge Zhou, Diane Johnson, Xing Xu & Xiaolin Wang - 2010.



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