Sinosauropteryx
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2008-07-10T07:18:21Z
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robot Adding: [[ca:Sinosauropteryx]]
{{Taxobox
| name = ''Sinosauropteryx''
| fossil_range = [[Early Cretaceous]]
| image = Sinosauropteryx prima.JPG
| image_width = 200px
| image_caption = ''Sinosauropteryx prima'' fossil displayed in Hong Kong Science Museum.
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Sauropsida]]
| superordo = [[Dinosaur]]ia
| ordo = [[Saurischia]]
| subordo = [[Theropoda]]
| unranked_familia = [[Coelurosauria]]
| familia = [[Compsognathidae]]
| genus = '''''Sinosauropteryx'''''
|genus_authority = Ji Q. & Ji S., 1996
|subdivision_ranks=[[Species]]
|subdivision=
*''S. prima'' <small>Ji Q. & Ji S., 1996 ([[type species|type]])</small>
}}
'''''Sinosauropteryx''''' (meaning "Chinese lizard-wing"<ref name="jiji1996">Ji, Q., and Ji, S. (1996). "On discovery of the earliest bird fossil in China and the origin of birds." ''Chinese Geology'' '''10''' (233): 30-33.</ref>) is the first and most primitive [[genus]] of [[dinosaur]] found with the fossilized impressions of [[feather]]s. It lived in [[China]] during the early [[Cretaceous period]] and may have been a close relative of ''[[Compsognathus]]''. It was the first dinosaur [[genus]] discovered in the famous [[Liaoning Province]]. The largest known specimens are 1-1.20 [[metre|meters]] (3 [[foot (unit of length)|ft]]) in length, most of which was taken up by its extremely long [[tail]]. The remarkably well-preserved fossils show that ''Sinosauropteryx'' was covered with a furry down of very simple feathers - though some contention arose with an alternative interpretation of the filamentous impression as collagen fiber remains. These filaments consisted of a simple two-branched structure, roughly similar to the secondarily primitive feathers of the modern [[kiwi]].
Three or four specimens are known: the [[holotype]] GMV 2123 (NIGP 127586), NIGP 127587, D 2141, and GMV 2124. The assignment of the latter to ''S. prima'' is disputed.<ref name=Jietal2007>Ji, S., Gao, C., Liu, J., Meng, Q., and Ji, Q. (2007). "New material of ''Sinosauropteryx'' (Theropoda: Compsognathidae) from western Liaoning, China." ''Acta Geologica Sinica (English Edition)'' '''81'''(2):177-182.</ref>
==Taxonomy==
[[Image:Sinosauropteryxskull.jpg|thumb|left|Mounted ''Sinosauropteryx'' skeleton cast, Zoological Museum, Copenhagen.]]
''Sinosauropteryx'' is important because it had feather-like structures, yet was not very closely related to the previous "first bird" ''[[Archaeopteryx]]''.<ref name="chenetal1998">Chen, P., Dong, Z., Zhen, S. (1998). "An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China." ''Nature'', '''391''', 147-152.</ref> There are many dinosaur families that were more closely related to ''Archaeopteryx'' than ''Sinosauropteryx'' was, including the [[deinonychosauria]]ns, the [[oviraptorosauria]]ns, and the [[therizinosaur]]oids. This indicates that feathers may have been a characteristic of many [[theropod]] dinosaurs, not just the obviously bird-like ones, making it possible that equally distant animals such as ''[[Ornitholestes]]'', ''[[Coelurus]]'', and ''[[Compsognathus]]'' had feathers as well, although their close proximity to the origin of feathers and the presence of scales on ''[[Juravenator]]'' and ''[[Tyrannosaurus]]'' make the distribution of feathers in primitive coelurosaurs extremely difficult to estimate accurately.
Most paleontologists do not consider ''Sinosauropteryx'' to be a bird, because [[phylogenetics|phylogenetically]], it lies far from the ''[[clade]]'' Aves, usually defined as ''Archaeopteryx'' + modern birds. The scientists who discovered and described ''Sinosauropteryx'', however, used a character-based ([[apomorphy]]) definition of the [[Class (biology)|Class]] Aves, that is, any animal with feathers is a bird. They argued that the filamentous plumes of ''Sinosauropteryx'' represent true feathers with a [[rachis]] and barbs, and therefore that ''Sinosauropteryx'' should be considered a true bird.<ref name="jiji1997">Ji, Q., and Ji, S. (1997). "Advances in ''Sinosauropteryx'' Research." ''Chinese Geology'', '''7''': 30-32.</ref> They classified it as belonging to a new biological [[order (biology)|order]], '''Sinosauropterygiformes''', family '''Sinosauropterygidae''', within the subclass [[Sauriurae]].<ref name="jiji1996"/>
==Diet==
The specimen GMV 2124 was found with three mammal jaws in its stomach region. Hurum, Luo & Kielan-Jaworowska (2006) identified these jaws as belonging to ''[[Zhangheotherium]]'' (two jaws) and ''[[Sinobaatar]]'' (the third jaw), showing that these two mammals were part of the ''Sinosauropteryx'' diet. Interestingly, ''[[Zhangheotherium]]'' is known to have had a poisonous spur, like the modern [[platypus]], showing that ''Sinosauropteryx'' fed on possibly poisonous mammals.<ref name="hurumetal2006">Hurum, Jørn H.; Luo, Zhe-Xi & Kielan-Jaworowska, Zofia (2006): Were mammals originally venomous? ''Acta Palaeontologica Polonica'' '''51'''(1): 1–11.[http://www.app.pan.pl/acta51/app51-001.pdf PDF fulltext]</ref>
More recently, it was proposed that GMV 2124 does not belong to ''Sinosauropteryx'' but to a distinct (possibly closely related) species with proportionally longer [[tibia]]e and a shorter tail.<ref name=Jietal2007/>
==Controversy==
{{seealso|Feathered dinosaurs}}
[[Image:Sinosauropteryxfossil.jpg|thumb|left|Fossil of ''Sinosauropteryx prima'' with possible proto-feather impressions.]]
Some researchers interpret the filamentous impression around ''Sinosauropteryx'' fossil as remains of [[collagen]] fiber, forming a frill on the back of the animal and underside of its tail.<ref name="linghan-soliaretal2007">Lingham-Soliar, T ''et al'' (2007) ''Proc. R. Soc. Lond. B'' doi:10.1098/rspb.2007.0352.</ref>
This hypothesis denies the proposal that ''Sinosauropteryx'' is the most [[basal (phylogenetics)|basal]] known theropod genus with feathers and also questions the current theory of feather origins itself. It calls into question the theory that the first feathers evolved not for [[flight]] but for insulation, and that they made their first appearance in relatively basal dinosaur lineages that later evolved into modern [[birds]]. <ref name="bald dino">[http://www.nature.com/news/2007/070521/full/070521-6.html Access : Bald dino casts doubt on feather theory : Nature News<!-- Bot generated title -->]</ref>
However, even if all of the known specimens of ''Sinosauropteryx'' that preserve feathery structures are invalidated, ''[[Dilong paradoxus|Dilong]]'', which is another basal, non - [[maniraptora]]n [[coelurosaur]], is known to have simple filamentous protofeathers preserved with its fossils.
==References==
{{reflist}}
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{{portalpar|Dinosaurs}}
[[Category:Dinosaurs of Asia]]
[[Category:Coelurosaurs]]
[[Category:Cretaceous dinosaurs]]
[[Category:Feathered dinosaurs]]
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