Instruct: Given a question, retrieve passages that answer the question.
Query: How large was the sinosauropteryx?
Sinosauropteryx was a small bipedal theropod, noted for its short arms, large first finger (thumbs), and long tail. The taxon includes some of the smallest known adult non-avian theropod specimens, with the holotype specimen measuring only 68cm (27in) in length, including the tail.[1] However, this individual was relatively young.[2] The longest known specimen reaches up to 1.07m (3.5ft) in length, with an estimated weight of 0.55kg (1.2lb).[3]
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, IVPPV14202. 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.[8] 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.[9]
Feduccia's frill argument was followed up in several other publications, in which researchers interpreted the filamentous impressions around Sinosauropteryx fossils as remains of collagen fibres rather than primitive feathers. Since the structures are clearly external to the body, these researchers have proposed that the fibres formed a frill on the back of the animal and underside of its tail, similar to some modern aquatic lizards.[19][20][21][22] The absence of feathers would refute the proposal that Sinosauropteryx is the most basal known theropod genus with feathers, and also raise questions about the current theory of feather origins itself. It calls into question the idea 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.[23]
Below is a cladogram showing the placement of Sinosauropteryx within Coelurosauria by Senter et al. in 2012.[29]
The same specimen of S. prima which had preserve a lizard in its stomach contents (NIGP127587) 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 36mm (1.4in) long by 26mm (1.0in) wide. The presence of two developed eggs suggests that Sinosauropteryx had dual oviducts and laid eggs in pairs, like other theropods.[1]
Three specimens have been assigned to Sinosauropteryx prima: the holotype GMV2123 (and its counter slab [opposite face], NIGP127586), NIGP127587, and D2141.[13] Another specimen, IVPPV14202, was assigned to the genus but not to the only species by Zhang and colleagues.[8] The assignment of an additional larger specimen to S. prima, GMV2124, was later found to be in error.[13][14] 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 124.6–122million years ago, during the early Aptian stage of the Early Cretaceous.[15]
Despite its feathers, most palaeontologists do not consider Sinosauropteryx to be a bird. Phylogenetically, the genus is only distantly related to the clade Aves, usually defined as Archaeopteryx lithographica plus modern birds. The scientists who described Sinosauropteryx, however, used a character-based, or apomorphic, definition of the Class Aves, in which any animal with feathers is considered to be a bird. They argued that the filamentous plumes of Sinosauropteryx represent true feathers with a rachis and barbs, and thus that Sinosauropteryx should be considered a true bird.[27] They classified the genus as belonging to a new biological order, Sinosauropterygiformes, family Sinosauropterygidae, within the subclass Sauriurae.[11] These proposals have not been accepted, and Sinosauropteryx is generally classified in the family Compsognathidae,[1][2][13] a group of small-bodied long-tailed coelurosaurian theropods known from the Late Jurassic and Early Cretaceous of Asia, Europe, and South America.[28]
China Dinosaurs Park (), also called China Dinosaurs Land is a theme park located in Changzhou, Jiangsu, China. It has been open since September 2000. The park covers more than 600 mu (0.27 km). As it is a theme park about dinosaurs, it is also called the "Eastern Jurassic Park". The museum contains a nearly complete fossil skeleton of the important dinosaur genus "Sinosauropteryx" (similar to "Archaeopteryx") as well as large fossils such as those of a "Brachiosaurus" and a "Hadrosaurus".
According to Zanno (2010b), "Beipiaosaurus" can be distinguished from its direct relatives based on the following characteristics, which are its unique derived traits, or autapomorphies:Soft-tissue impressions from the type specimen of "B. inexpectus" indicated that the body was covered predominately by downy feather-like fibers, similar to those of "Sinosauropteryx", but longer, and oriented perpendicular to the arm. Xu "et al.", who described the specimen, suggested that these downy feathers represent an intermediate stage between "Sinosauropteryx" and more advanced birds (Avialae). The tail was covered in feathers between four and seven centimeters long, consisting of parallel filaments with a width of 1.5 millimeters, without a trace of pennaceous feathers or a tail fan.
The specimen NIGP127587 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.[1] 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.[9]
Sinosauropteryx (meaning "Chinese reptilian wing", Chinese:中华龙鸟; pinyin:Zhōnghuá lóng niǎo; literally: 'Chinese dragon bird') 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.
All described specimens of Sinosauropteryx preserve integumentary structures (filaments arising from the skin) which most palaeontologists interpret as very primitive type of feathers. These short, down-like filaments are preserved along the back half of the skull, the arms, neck, back, and top and bottom of the tail. Additional patches of feathers have been identified on the sides of the body, and palaeontologists Chen, Dong and Zheng proposed that the density of the feathers on the back and the randomness of the patches elsewhere on the body indicated the animals would have been fully feathered in life, with the ventral feathers having been removed by decomposition.[1]
Sinosauropteryx was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to 1.07 metres (3.51 feet) in length, with an estimated weight of 0.55 kilograms (1.21 pounds) It was a close relative of the similar but older genus Compsognathus, both genera belonging to the family Compsognathidae. Only one species of Sinosauropteryx has been named: S. prima, meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.
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.[16] 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.[17] Subsequent publications saw some of the team members disagreeing over the identity of the structures.[2][18]
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 was anatomically similar to Compsognathus, differing from its European relatives in its proportions. The skull of Sinosauropteryx was 15% longer than its thigh bones, unlike in Compsognathus, where the skull and thigh bones are approximately equivalent in length. The arms of Sinosauropteryx (humerus and radius) were only 30% the length of its legs (thigh bone and shin), compared to 40% in Compsognathus.[1] Additionally, Sinosauropteryx had several features unique among all other theropods. It had 64 vertebrae in its tail. This high number made its tail the longest relative to body length of any theropod.[1] Its hands were long compared to its arms, about 84% to 91% of the length of the rest of the arm (humerus and radius), and half the length of the foot. The first and second digits were about the same length, with a large claw on the first digit.[2] The first fingers were large, being both longer and thicker than either of the bones of the forearm.[1] The teeth differed slightly (they were heterodont) based on position: those near the tips of the upper jaws (on the premaxillae) were slender and lacked serrations, while those behind them (on the maxillae) were serrated and laterally compressed. The teeth of the lower jaws were similarly differentiated.[2]
However, a 2018 study considered that the thick filaments could simply be bundles of thin filaments overlapping each other. This possibility is supported by the observation that thin filaments tend to run parallel to both each other and thick filaments, rather than branching out as earlier authors identified. Some of the thick filaments are quite long yet end in small tufts of thin filaments. Plumaceous, down-like feathering typically has an opposite appearance, with a short central quill and long tufts. In addition, the thick filaments preserve no evidence of Calcium phosphate, the mineral which modern feather quills are made of. The large amount of curvature present in the filaments also makes a strong central quill unlikely. Thus, the idea that thick filaments are simply bundles of thin filaments is less unusual than the idea that they were a variant of quilled plumaceous feathers which developed a morphology opposite that of birds and other feathered theropods. As a whole, the study preferred the hypothesis that Sinosauropteryx feathers were simple single-branch filaments, although it is conceivable that they were occasionally joined at the base into tufts as predecessors to down-like plumaceous feathers.[5]
The plate of the German "Compsognathus" shows several circular irregularities in diameter near the skeletal remains. Peter Griffiths interpreted them as immature eggs in 1993. However, later researchers have doubted their connection to the genus because they were found outside the body cavity of the animal. A well-preserved fossil of a "Sinosauropteryx", a genus related to "Compsognathus", shows two oviducts bearing two unlaid eggs. These proportionally larger and less numerous eggs of "Sinosauropteryx" cast further doubt on the original identification of the purported "Compsognathus" eggs. In 1964 German geologist Karl Werner Barthel had explained the discs as gas bubbles formed in the sediment because of the putrefaction of the carcass.
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."[10] When originally described, the authors named Sinosauropteryx, meaning "Chinese Reptilian Wing.[11]
While first classified as a member of the Compsognathidae, subsequent studies have found problems with the initial study that produced those findings. Rather than grouping it with "Sinosauropteryx" and other compsognathids, Butler "et al." found that it was not a compsognathid, but rather a basal member of the group Maniraptora. Studies conflict on whether or not compsognathids belong to this later group or are more primitive. Additional work published by Luis Chiappe and Ursula Göhlich in 2010 found that "Juravenator" was most similar in anatomy to "Compsognathus", and that it probably did belong to the Compsognathidae if that is actually a natural group. They also suggested that "compsognathids", including "Juravenator", may form a grade of primitive coelurosaurs rather than a monophyletic clade. In 2011 Cristiano dal Sasso and Simone Maganuco published an analysis which recovered the Compsognathidae as a natural group and "Juravenator" belonging to it as a sister species of "Sinosauropteryx". However, a large analysis of coelurosaurs published in 2013 again found "Juravenator" to be a coelurosaur closely related to, but not a member of, the Compsognathidae. Instead, it was recovered as a close relative of "Ornitholestes" outside the clade Maniraptoriformes.
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.[1] 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.[7]
There is only one named species of Sinosauropteryx, S. prima. A possible second species is represented by the specimen GMV2124 (aka NGMC2124), which was described as a third, larger specimen of S. prima by Ji and Ji in 1997.[27] 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 GMV2124 was a compsognathid coelurosaurian, while Sinosauropteryx proper was a more primitive kind of coelurosaurian or even a basal carnosaurian.[7] 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.[14] Also in 2007, Ji, Ji and colleagues wrote that GMV2124 is probably a new genus, noting the differences in tail length and hindlimb proportions.[13]
The possible Sinosauropteryx specimen GMV2124 (Sinosauropteryx?sp.) was found with three mammal jaws in its gut region. Hurum, Luo, and Kielan-Jaworowska (2006) identified two of these jaws as belonging to Zhangheotherium and the third to Sinobaatar, showing that these two mammals were part of the animal's diet. Zhangheotherium is known to have had a spur on the ankle, like the modern platypus, which would indicate that Sinosauropteryx fed on possibly venomous mammals.[30]
Sinosauropteryx, as a Yixian Formation dinosaur, is a member of the Jehol Biota, the assemblage of organisms found in the Yixian Formation and overlying Jiufotang Formation.[15] The Yixian Formation is composed largely of volcanic rocks such as andesite and basalt. Between the volcanic layers are several beds of sedimentary rocks representing deposition in a lake.[1] The freshwater lake strata of the Yixian Formation have preserved a wide variety of plants, invertebrates, and vertebrates. Gymnosperm forests were extensive, with a few early flowering plants as well. Ostracods and insects were diverse, and bivalves and gastropods were abundant. Mammals and birds are also well-known from the formation. The setting was subject to periodic mortality events including volcanic eruptions, wildfires, and noxious gases erupting from the lakes.[15] The climate has been interpreted as temperate, with distinct wet and dry seasons.[31] The yearly temperature during this time period averaged about 10°C (50°F), indicating a temperate climate with unusually cold winters for the generally warm Mesozoic era, possibly due to northern China's high latitude during this time.[32]
The hypothesis that the structures were collagen fibers was closely analyzed and disproven by a 2017 paper published by Smithwick et al. The integument of Sinosauropteryx was closely compared to less controversial evidence of collagen fibers preserved in the ichthyosaur Stenopterygius. Although the collagen hypothesis claimed that the central shafts (rachises) of purported theropod feathers were actually misidentified examples of shaft-like collagen fibers, higher quality imagery showed that these similarities were artificial. The supposed shafts in ichthyosaur collagen were actually scratch marks, cracks, and crevasses created during preparation of one of the ichthyosaur specimens. On the other hand, the shafts in the Sinosauropteryx specimens were legitimate examples of fossilized structures. The collagen hypothesis also claims that Sinosauropteryx integument includes beaded structures similar to structures occasionally found in decaying collagen of modern sea mammals. However, this claim was also unsupported, with Smithwick et al. finding no evidence of the beaded structures which collagen hypothesis proponents identified on the specimens. The study proposes that some areas of the fossil preserved in three dimensions cast shadows which would have resembled beaded structures in low quality photographs.[26]