When did the sinosauropteryx live?
871655#16
Three specimens have been assigned to "Sinosauropteryx prima": the holotype GMV 2123 (and its counter slab [opposite face], NIGP 127586), NIGP 127587, and D 2141. Another specimen, IVPP V14202, was assigned to the genus but not to the only species by Zhang and colleagues. The assignment of an additional larger specimen to "S. prima", GMV 2124, was later found to be in error. All of the fossils were found in the Jianshangou or Dawangzhangzi Beds of the Yixian Formation in the Beipiao and Lingyuan regions of Liaoning, China. These fossil beds have been dated to 124.6–122 million years ago, during the early Aptian stage of the Early Cretaceous.
Sinosauropteryx
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The first fossil specimen of the dinosaur later named "Sinosauropteryx prima" was uncovered in August 1996 by Li Yumin. Yumin was a farmer and part-time fossil hunter who often prospected around Liaoning Province to acquire fossils to sell to individuals and museums. Yumin recognized the unique quality of the specimen, which was separated into two slabs, and sold the slabs to two separate museums in China: the National Geological Museum in Beijing, and the Nanjing Institute of Geology and Paleontology. The director of the Beijing museum, Ji Qiang, recognized the importance of the find, as did visiting Canadian palaeontologist Phil Currie and artist Michael Skrepnick, who became aware of the fossil by chance as they explored the Beijing museum's collections after leading a fossil tour of the area during the first week of October, 1996. Currie recognized the significance of the fossil immediately. As "The New York Times" quoted him, "When I saw this slab of silt stone mixed with volcanic ash in which the creature is embedded, I was bowled over." When originally described, the authors named "Sinosauropteryx", meaning "Chinese Reptilian Wing".
Sinosauropteryx
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"Sinosauropteryx" lived in what is now northeastern China during the early Cretaceous period. It was among the first dinosaurs discovered from the Yixian Formation in Liaoning Province, and was a member of the Jehol Biota. Well-preserved fossils of this species illustrate many aspects of its biology, such as its diet and reproduction.
Sinosauropteryx
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Controversy regarding the identity of the filaments preserved in the first "Sinosauropteryx" specimen began almost immediately, as the team of scientists spent three days in Beijing examining the specimen under a microscope. The results of their studies (reported during a press conference at the Philadelphia Academy of Natural Sciences on Thursday, April 24, 1997) were inconclusive; the team agreed that the structures preserved on "Sinosauropteryx" were not modern feathers, but suggested further research was required to discover their exact nature. Palaeontologist Alan Feduccia, who had not yet examined the specimen, wrote in "Audubon Magazine" that the structures of "Sinosauropteryx" (which he considered at the time to be a synonym of "Compsognathus", as "Compsognathus prima") were stiffening structures from a frill running along the back, and that dinosaur palaeontologists were engaging in wishful thinking when equating the structures with feathers. Subsequent publications saw some of the team members disagreeing over the identity of the structures.
Sinosauropteryx
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The specimen NIGP 127587 was preserved with the remains of a lizard in its gut region, indicating that small, fast-moving animals made up part of the diet of "Sinosauropteryx prima". Numerous lizards of this type have been found in the same rocks as "Sinosauropteryx". These lizards have been interpreted as most likely belonging to the genus "Dalinghosaurus". "Dalinghosaurus" was probably a fast-running lizard adapted to living in open habitats, much like "Sinosauropteryx" itself.
Sinosauropteryx
871655#0
Sinosauropteryx (meaning "Chinese reptilian wing", ) is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae (birds and their immediate relatives) to be found with evidence of feathers. It was covered with a coat of very simple filament-like feathers. Structures that indicate colouration have also been preserved in some of its feathers, which makes "Sinosauropteryx" the first non-avialian dinosaurs where colouration has been determined. The colouration includes a reddish and light banded tail. Some contention has arisen with an alternative interpretation of the filamentous impression as remains of collagen fibres, but this has not been widely accepted.
Sinosauropteryx
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"Sinosauropteryx" was the first dinosaur to have its life colouration described by scientists based on physical evidence. Some fossils of "Sinosauropteryx" show an alternation of lighter and darker bands preserved on the tail. Chen and colleagues initially interpreted this banding pattern as an artifact of the splitting between the main slab and counter-slab in which the original specimen was preserved. However, Longrich suggested in his 2002 presentation for the Society of Vertebrate Paleontology that these specimens actually preserve remnants of the colouration pattern the animal would have exhibited in life. He argued that the dark, banded areas on the tail were too evenly spaced to have been caused by random separation of the fossil slabs, and that they represent fossilized pigments present in the feathers. Additionally, rather than an artifact of preservation or decomposition, the presence of dark feathers along only the top of the body may also reflect the colour pattern in life, indicating that "Sinosauropteryx prima" was countershaded with dark colouration on its back and lighter colouration on its underside, with bands or stripes on the tail for camouflage.
Sinosauropteryx
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Longrich's conclusions were supported in a paper first published online in the journal "Nature" in January 2010. Fucheng Zhang and colleagues examined the fossilized feathers of several dinosaurs and early birds, and found evidence that they preserved melanosomes, the cells that give the feathers of modern birds their colour. Among the specimens studied was a previously undescribed specimen of "Sinosauropteryx", IVPP V14202. By examining melanosome structure and distribution, Zhang and colleagues were able to confirm the presence of light and dark bands of colour in the tail feathers of "Sinosauropteryx". Furthermore, the team was able to compare melanosome types to those of modern birds to determine a general range of colour. From the presence of phaeomelanosomes, spherical melanosomes that make and store red pigment, they concluded that the darker feathers of "Sinosauropteryx" were chestnut or reddish brown in colour. More research on the coloration of "Sinosauropteryx" reveals that it had a raccoon-like bandit mask and countershading patterns most likely associated with an open habitat, indicating that the Jehol likely had a range of habitat types.
Sinosauropteryx
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The same specimen of "S. prima" which had preserve a lizard in its stomach contents (NIGP 127587) also had several small eggs in its abdomen. Two eggs were preserved just in front of and above the pubic boot, and several more may lie underneath them on the slab. It is unlikely that they were eaten by the animal, as they are in the wrong part of the body cavity for the egg shells to have remained intact. It is more likely that they are unlaid eggs produced by the animal itself, proving the specimen to be a female. Each egg measured long by wide. The presence of two developed eggs suggests that "Sinosauropteryx" had dual oviducts and laid eggs in pairs, like other theropods.
Sinosauropteryx
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Below is a cladogram showing the placement of "Sinosauropteryx" within Coelurosauria by Senter "et al." in 2012.
There is only one named species of "Sinosauropteryx", "S. prima". A possible second species is represented by the specimen GMV 2124 (aka NGMC 2124), which was described as a third, larger specimen of "S. prima" by Ji and Ji in 1997. However, in a 2002 presentation and abstract for the Society of Vertebrate Paleontology, Nick Longrich showed that this specimen differs in several anatomical aspects from the others, including its relatively large size, proportionally longer shins, and shorter tail. Longrich suggested that GMV 2124 was a compsognathid coelurosaurian, while "Sinosauropteryx" proper was a more primitive kind of coelurosaurian or even a basal carnosaurian. In 2007, Gishlick and Gauthier concurred that this specimen was probably a new taxon, and tentatively re-classified it as "Sinosauropteryx?" sp., though they suggested it may belong in a new genus. Also in 2007, Ji, Ji and colleagues wrote that GMV 2124 is probably a new genus, noting the differences in tail length and hindlimb proportions.
Sinosauropteryx