Sinosauropteryx

Sinosauropteryx (meaning "Chinese reptilian wing", simplified Chinese: 中华龙鸟; traditional Chinese: 中華龍鳥; 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.

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.

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
Temporal range: Early Cretaceous, 124.6–122 Ma
Sinosauropteryxfossil
Holotype specimen with filament impressions, Inner Mongolia Museum
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Compsognathidae
Genus: Sinosauropteryx
Ji & Ji, 1996
Species:
S. prima
Binomial name
Sinosauropteryx prima
Ji & Ji, 1996

Description

Sinosauropteryx scale
Size of adult and sub-adult specimens, compared with a human

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 68 cm (27 in) in length, including the tail.[1] However, this individual was relatively young.[2] The longest known specimen reaches up to 1.07 m (3.5 ft) in length, with an estimated weight of 0.55 kg (1.2 lb).[3]

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]

A pigmented area in the abdomen of the holotype has been suggested as possible traces of organs,[1] and was interpreted as the liver by John Ruben and colleagues, which they described as part of a crocodilian-like "hepatic piston" respiratory system.[4] A later study, while agreeing that the pigmented area represented something originally inside the body, found no defined structure and noted that any organs would have been distorted by the processes that flattened the skeleton into an essentially two-dimensional form.[2] Dark pigment is also present in the eye region of the holotype and another specimen.[1]

Feathers

Sinosauropteryx-1
Holotype and referred specimen with diagrams showing feathers and internal tissue

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]

The filaments are preserved with a gap between the bones, which several authors have noted corresponds closely to the expected amount of skin and muscle tissue that would have been present in life. The feathers are closest to the bone on the skull and end of the tail, where little to no muscle was present, and the gap increases over the back vertebrae, where more musculature would be expected, indicating that the filaments were external to the skin and do not correspond with subcutaneous structures.[1]

Sinosauropteryx plumage fossils
Preserved plumage in various specimens

The filaments exhibit random orientations and are often wavy, which has been interpreted as evidence that they were soft and pliable in life. Microscopic examination shows that individual filaments appear dark along the edges and light internally, suggesting that they were hollow, like modern feathers. Compared to modern mammals the filaments were quite coarse, with each individual strand much larger and thicker than the corresponding hairs of similarly sized mammals.[1]

The length of the filaments varies across the body. On the type specimen, they are shortest just in front of the eyes, with a length of 13 mm (0.51 in). Going further along the body, the filaments rapidly increase in length until reaching lengths of 35 mm (1.4 in) over the shoulder blades. The length remains uniform over the back, until beyond the hips, when the filaments lengthen again and reach their maximum length midway down the tail at 40 mm (1.6 in). The filaments on the underside of the tail are shorter overall and decrease in length more rapidly than those on the dorsal surface. By the 25th tail vertebrae, the filaments on the underside reach a length of only 35 mm (1.4 in). The longest feathers present on the forearm measured 14 mm (0.55 in).[1]

Though the feathers are too dense to isolate a single structure for examination, several studies have suggested the presence of two distinct filament types (thick and thin) interspersed with each other. The thick filaments tend to appear 'stiffer' than thin filaments, and the thin filaments tend to lie parallel to each other but at angles to nearby thick filaments. These properties suggest that the individual feathers consisted of a central quill (rachis) with thinner barbs branching off from it, similar to but more primitive in structure than modern bird feathers.[2] Overall, the filaments most closely resemble the "plumules" or down-like feathers of some modern birds, with a thick central quill and long, thin barbs. The same structures are seen in other fossils from the Yixian Formation, including Confuciusornis.[1]

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]

While Sinosauropteryx had feather-like structures, it was not very closely related to the previous "first bird" Archaeopteryx.[1] There are many dinosaur clades that were more closely related to Archaeopteryx than Sinosauropteryx was, including the deinonychosaurians, the oviraptorosaurians, and the therizinosauroids.[6] This indicates that feathers may have been a characteristic of many theropod dinosaurs, not just the obviously bird-like ones, making it quite likely that equally distant animals such as Compsognathus had feathers as well.[6]

Colouration

Sinosauropteryx color
Restoration illustrating colouration as suggested by the study of preserved melanosomes

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]

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.[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]

History of discovery

Sinosauropteryx
Skeletal diagram showing known remains of the holotype and a referred specimen

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 siltstone 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]

Chinese authorities initially barred photographs of the specimen from publication. However, Currie brought a photograph to the 1996 meeting of the Society of Vertebrate Paleontology at the American Museum of Natural History in New York, causing crowds of palaeontologists to gather and discuss the new discovery. The news reportedly left palaeontologist John Ostrom, who in the 1970s had pioneered the theory that birds evolved from dinosaurs, "in a state of shock."[10] Ostrom later joined an international team of researchers who gathered in Beijing to examine the fossils; other team members included feather expert Alan Brush, fossil bird expert Larry Martin, and Peter Wellnhofer, an expert on the early bird Archaeopteryx.[12]

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.[13] Another specimen, IVPP V14202, 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, GMV 2124, 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 124.6–122 million years ago, during the early Aptian stage of the Early Cretaceous.[15]

Identity of filaments

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]

ISinosauropteryx-Geological Museum of China
Counter slab of the holotype, on display at the Geological Museum of China

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]

Most researchers have disagreed with the identification of the structures as collagen or other structural fibres. Notably, the team of scientists that reported the presence of pigmentation cells in the structures argued that their presence proved the structures were feathers, not collagen, because collagen does not contain pigment.[8][24] Gregory S. Paul reidentified what the collagen hypothesis's proponents consider a body outline outside of the fibres as an artefact of preparation: breakage and brushed-on sealant have been misidentified as the outline of the body.[25]

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]

Other examples of purported collagen fibers in the tail area were revealed to be scratches, similar to those on the rest of the specimen. An area of the bone with an irregular surface was considered evidence that some collagen fibers were less decayed than others. However, Smithwick et al.'s study noted that, after further preparation, this irregular surface was simply a layer of sediment with a different color than the rest of the slab. The 'frill' or 'halo' of collagen identified by Feduccia was also determined to be misidentified sediment surrounding one of the specimens. Smithwick et al.'s study concluded by stating that the integument preserved on Sinosauropteryx closely resembled that of birds preserved in the same formation. Purported features of collagen fibers were in fact misidentified shadows formed by scratches or irregular sediment, a misidentification perpetuated by the low quality of early Sinosauropteryx photographs.[26]

Classification

Sinosauropteryx prima
Undescribed fossil specimen at the Hong Kong Science Museum
Sinosauropteryx GMV 2124
Cast of the skeleton belonging to GMV 2124, which is probably not a Sinosauropteryx

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]

Below is a cladogram showing the placement of Sinosauropteryx within Coelurosauria by Senter et al. in 2012.[29]

Coelurosauria
Tyrannosauroidea
Coeluridae

Coelurus

Tanycolagreus

Dilong

Guanlong

Raptorex

Gorgosaurus

Daspletosaurus

Tyrannosaurus

Compsognathidae

Sinocalliopteryx

Huaxiagnathus

Sinosauropteryx

Compsognathus

Juravenator

Scipionyx

Maniraptoriformes

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.[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 GMV 2124 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 GMV 2124 is probably a new genus, noting the differences in tail length and hindlimb proportions.[13]

Distinguishing anatomical features

Ji and Ji (1996) identified many features that set Sinosauropteryx apart from other birds and dinosaurs. They found that it was a small primitive bird with a relatively high skull, blunt rostrum and a slightly high premaxilla; that the antorbital fenestra was elliptical but not enlarged, the dentary was robust, the surangular was narrow and elongated, and the dentition is extremely well developed and acute; that there are over 50 extremely elongated caudals, constituting 60% of the body length, and the forelimb is extremely short with a short and thick humerus; the pubis was elongated and extremely inflated at its distal end and the ischium is broad; the hind limb was long and robust, the tibia is only slightly longer than the femur, the tarsals are separated, and the metatarsals are relatively robust with unfused proximal ends; the feathers are short, small, and uniform; many ornament the top of the skull, cervical, and dorsal regions, in addition to the dorsal and ventral caudal region.[11]

Palaeobiology

Diet

Sinosauropteryx with Dalinghosaurus
Restoration of Sinosauropteryx preying on Dalinghosaurus, by Bob Nicholls

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.[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]

The possible Sinosauropteryx specimen GMV 2124 (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]

Reproduction

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 36 mm (1.4 in) long by 26 mm (1.0 in) wide. The presence of two developed eggs suggests that Sinosauropteryx had dual oviducts and laid eggs in pairs, like other theropods.[1]

Palaeoecology

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]

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  28. ^ Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton, NJ: Princeton University Press. p. 117. ISBN 978-0-691-13720-9.
  29. ^ Senter, P.; Kirkland, J. I.; Deblieux, D. D.; Madsen, S.; Toth, N. (2012). Dodson, Peter (ed.). "New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail". PLoS ONE. 7 (5): e36790. Bibcode:2012PLoSO...736790S. doi:10.1371/journal.pone.0036790. PMC 3352940. PMID 22615813.
  30. ^ Hurum, J.H.; Luo, Z.-X.; Kielan-Jaworowska, Z. (2006). "Were mammals originally venomous?". Acta Palaeontologica Polonica. 51 (1): 1–11.
  31. ^ Wang, Y.; Zheng, S.; Yang, X.; Zhang, W.; and Ni, Q. (2006). "The biodiversity and palaeoclimate of conifer floras from the Early Cretaceous deposits in western Liaoning, northeast China." International Symposium on Cretaceous Major Geological Events and Earth System. p. 56A.
  32. ^ Amiot, R., Wang, X., Zhou, Z., Xiaolin Wang, X., Buffetaut, E., Lécuyer, C., Ding, Z., Fluteau, F., Hibino, T., Kusuhashi, N., Mo, J., Suteethorn, V., Yuanqing Wang, Y., Xu, X., and Zhang, F. (2011). "Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates." Proceedings of the National Academy of Sciences, 108(13): 5179-5183. doi: 10.1073/pnas.1011369108

External links

Aptian

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous.The Aptian partly overlaps the upper part of the regionally used (in Western Europe) stage Urgonian.

The Selli Event, also known as OAE1a, was one of two oceanic Anoxic events in the Cretaceous period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.

Beipiaosaurus

Beipiaosaurus is a genus of therizinosauroid theropod dinosaur from the Early Cretaceous of China. Before the discovery of Yutyrannus, it was among the largest dinosaurs known from direct evidence to be feathered.

The exact classification of therizinosaurs had in the past been hotly debated, since their prosauropod-like teeth and body structure indicate that they were generally herbivorous, unlike typical theropods. Beipiaosaurus, being considered to be a primitive therizinosauroid, has features which suggest that all therizinosauroids, including the more derived Therizinosauridae, to be coelurosaurian theropods, not sauropodomorph or ornithischian relatives as once believed.

China Dinosaurs Park

China Dinosaurs Park (Chinese: 中华恐龙园), 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 km2). 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.

Changzhou Travel and Tourism Administration regards China Dinosaur Park as the most amusing base for science education. The park focuses on creating a harmonious ecological environment. There are 70 different kinds of trees and more than 4,000 plants in the park. The afforested areas comprise 70 percent of the total area. There are nearly twenty kinds of amusements for tourists to enjoy themselves.

The symbolic building in the park is the museum of dinosaurs. The museum covers about 20,000 square meters, and contains more than ten halls, including "Evolution Hall" and "Woods Hall". The first floor of the museum is taken up by the skeleton of a dinosaur. You can also see many kinds of fossils of dinosaurs in the museum. In addition, there are a lot of amusing high-fidelity game facilities. All the games are related to dinosaurs, such as "Pterodactyl's movement" and "Hot dance of the dinosaur car". Another attractive place in the park is the hot spring pool. Every year there is a big festival in the park called International Lantern Festival. During this festival, there are many fireworks and beautiful lanterns in the park. If there is any festival approaching, Changzhou China Dinosaur Park will also present a big parade in which many people dressed in cartoon costumes dance and sing together. The parade sometimes shows classic scenes from cartoon films or computer games, such as 'Baby Dinosaur'.

Coelurosauria

Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrannosaurs, ornithomimosaurs, and maniraptorans; Maniraptora includes birds, the only dinosaur group alive today.Most feathered dinosaurs discovered so far have been coelurosaurs. Philip J. Currie considers it likely and probable that all coelurosaurs were feathered. In the past, Coelurosauria was used to refer to all small theropods, but this classification has since been abolished.

Compsognathidae

Compsognathidae is a family of coelurosaurian theropod dinosaurs. They were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other dinosaurs such as Archaeopteryx inspired the idea for the connection between dinosaur reptiles and modern-day avian species. Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator. While the latter three show evidence of a covering of some of the earliest primitive feathers over much of the body, Juravenator and Compsognathus also show evidence of scales on the tail or hind legs.

The first member of the group, Compsognathus, was discovered in 1861, after Johann A. Wagner published his description of the taxon. The family it was created by Edward Drinker Cope in 1875. This classification was accepted by Othniel Charles Marsh in 1882, and added to the Coelurosauria clade by Friedrich von Huene in 1914 after additional fossils had been found. With further discoveries, fossils have been uncovered across three different continents, in the countries of China, France, Germany, Italy, and Brazil. Assignment to Compsognathidae is usually determined through examination of the metacarpal, which is used to separate Compsognathidae from other dinosaurs. However, classification is still complicated due to similarities to the body of several other theropod dinosaurs, as well as the lack of unifying, diagnostic features that are shared by all compsognathids.

Compsognathus

Compsognathus (; Greek kompsos/κομψός; "elegant", "refined" or "dainty", and gnathos/γνάθος; "jaw") is a genus of small, bipedal, carnivorous theropod dinosaur. Members of its single species Compsognathus longipes could grow to around the size of a turkey. They lived about 150 million years ago, during the Tithonian age of the late Jurassic period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany in the 1850s and the second in France more than a century later. Today, C. longipes is the only recognized species, although the larger specimen discovered in France in the 1970s was once thought to belong to a separate species and named C. corallestris.

Many presentations still describe Compsognathus as "chicken-sized" dinosaurs because of the size of the German specimen, which is now believed to be a juvenile. Compsognathus longipes is one of the few dinosaur species whose diet is known with certainty: the remains of small, agile lizards are preserved in the bellies of both specimens. Teeth discovered in Portugal may be further fossil remains of the genus.

Although not recognized as such at the time of its discovery, Compsognathus is the first theropod dinosaur known from a reasonably complete fossil skeleton. Until the 1990s, it was the smallest-known non-avialan dinosaur, with the preceding centuries incorrectly labelling them as the closest relative of Archaeopteryx.

Compsognathus was the first dinosaur genus to be portrayed with feathers, by Thomas Henry Huxley in 1876.

Dalinghosaurus

Dalinghosaurus (often incorrectly spelled "Dalinghesaurus") is an extinct genus of lizards, first described in 1998 by S.A. Ji of the Peking University Department of Geology. The type species is Dalinghosaurus longidigitus.

Dinosaur coloration

Dinosaur color is one of the unknowns in the field of paleontology as skin pigmentation is nearly always lost during the fossilization process. However, recent studies of feathered dinosaurs have shown that we might be able to infer the color of some species through the use of melanosomes, the color-determining pigments within the feathers.

Feathered dinosaur

Since scientific research began on dinosaurs in the early 1800s, they were generally believed to be closely related to modern reptiles, such as lizards. The word "dinosaur" itself, coined in 1842 by paleontologist Richard Owen, comes from the Greek for "fearsome lizard". This view began to shift during the so-called dinosaur renaissance in scientific research in the late 1960s, and by the mid-1990s significant evidence had emerged that dinosaurs were much more closely related to birds, which descended directly from the theropod group of dinosaurs and are themselves a subgroup within the Dinosauria.

Understanding of the origin of feathers developed both as new fossils were discovered throughout the 2000s and 2010s and as technology has enabled scientists to study fossils more closely. Among non-avian dinosaurs, feathers or feather-like integument have been discovered in dozens of genera via direct and indirect fossil evidence. Although the vast majority of feather discoveries have been in coelurosaurian theropods, feather-like integument has also been discovered in at least three ornithischians, suggesting that feathers may have been present on the last common ancestor of the Ornithoscelida, a dinosaur group including both theropods and ornithischians. It is possible that feathers first developed in even earlier archosaurs, in light of the discovery of highly feather-like pycnofibers in pterosaurs. Crocodilians also possess beta keratin similar to those of birds, which suggests that they evolved from common ancestral genes.

Huaxiagnathus

Huaxiagnathus is a genus of theropod dinosaur from the Lower Cretaceous of China. It was a compsognathid, large for that group at about half a meter longer than Compsognathus and larger specimens of Sinosauropteryx, with the largest specimen about 1.8 meters (5.9 feet) in length.

The name Huaxiagnathus is derived from the Chinese Hua Xia, 華夏, a traditional word for "China", and from the Greek gnathos, Latinised into gnathus, meaning "jaw."

Juravenator

Juravenator is a genus of small (75 cm long) coelurosaurian theropod dinosaur, which lived in the area which would someday become the top of the Franconian Jura of Germany, about 151 or 152 million years ago. It is known from a single, juvenile specimen.

List of fossils with consumulites

This list of fossils with consumulites contains fossil specimens discovered to contain the preserved remains of food that the deceased animal had ingested during life. Such consumulites are a type of bromalite, the broader term applied to fossilized material ingested by an animal including waste expelled from the body like feces (coprolites) and vomit (regurgitalites). Consumulites are divided into three categories food in the animal's mouth when it died (oralites), food in the animal's throat when it died (esophagolites), partially digested stomach contents (gastrolites, not to be confused with gastroliths), and food found in the animal's intestinal tract (cololites).

List of non-avian dinosaur species preserved with evidence of feathers

Several non-avian dinosaurs were feathered. Direct evidence of feathers exists for the following species, listed in the order currently accepted evidence was first published. In all examples, the evidence described consists of feather impressions, except those genera inferred to have had feathers based on skeletal or chemical evidence, such as the presence of quill knobs (the anchor points for wing feathers on the forelimb) or a pygostyle (the fused vertebrae at the tail tip which often supports large feathers).

Ostromia crassipes (1970)

Avimimus portentosus (inferred 1987: ulnar ridge)

Sinosauropteryx prima (1996)

Fulicopus lyellii, an ichnotaxon, possible squatting Dilophosaurus or similar. (1996)

Protarchaeopteryx robusta (1997)

GMV 2124 (1997)

Caudipteryx zoui (1998)

Rahonavis ostromi (inferred 1998: quill knobs; possibly avialan)

Shuvuuia deserti (1999)

Beipiaosaurus inexpectus (1999)

Sinornithosaurus millenii (1999)

Caudipteryx dongi (2000)

Caudipteryx sp. (2000)

Microraptor zhaoianus (2000)

Nomingia gobiensis (inferred 2000: pygostyle)

Psittacosaurus sp.? (2002)

Scansoriopteryx heilmanni (2002; possibly avialan)

Yixianosaurus longimanus (2003)

Dilong paradoxus (2004)

Pedopenna daohugouensis (2005; possibly avialan)

Jinfengopteryx elegans (2005)

Juravenator starki (2006)

Sinocalliopteryx gigas (2007)

Velociraptor mongoliensis (inferred 2007: quill knobs)

Epidexipteryx hui (2008; possibly avialan)

Similicaudipteryx yixianensis (inferred 2008: pygostyle; confirmed 2010)

Anchiornis huxleyi (2009; possibly avialan)

Tianyulong confuciusi? (2009)

Concavenator corcovatus? (inferred 2010: quill knobs?)

Xiaotingia zhengi (2011; possibly avialan)

Yutyrannus huali (2012)

Sciurumimus albersdoerferi (2012)

Ornithomimus edmontonicus (2012)

Ningyuansaurus wangi (2012)

Eosinopteryx brevipenna (2013; possibly avialan)

Jianchangosaurus yixianensis (2013)

Aurornis xui (2013; possibly avialan)

Changyuraptor yangi (2014)

Kulindadromeus zabaikalicus? (2014)

Citipati osmolskae (inferred 2014: pygostyle)

Conchoraptor gracilis (inferred 2014: pygostyle)

Deinocheirus mirificus? (inferred 2014: pygostyle)

Yi qi (2015)

Ornithomimus sp. (2015)

Zhenyuanlong suni (2015)

Dakotaraptor steini (inferred 2015: quill knobs)

Apatoraptor pennatus (inferred 2016: quill knobs)

Jianianhualong tengi (2017)

Serikornis sungei (2017)

Caihong juji (2018)

Xingtianosaurus ganqi (2019)

Ambopteryx longibrachium (2019)Note that the filamentous structures in some ornithischian dinosaurs (Psittacosaurus, Tianyulong and Kulindadromeus) and the pycnofibres found in some pterosaurs may or may not be homologous with the feathers of theropods.

Philip J. Currie

Philip John Currie (born March 13, 1949) is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton. In the 1980s he became the director of the Canada-China Dinosaur Project, the first cooperative palaeontological partnering between China and the West since the Central Asiatic Expeditions in the 1920s, and helped describe some of the first feathered dinosaurs. He is one of the primary editors of the influential Encyclopedia of Dinosaurs, and his areas of expertise include theropods (especially Tyrannosauridae), the origin of birds, and dinosaurian migration patterns and herding behavior. He was one of the models for palaeontologist Alan Grant in the film Jurassic Park.

Sinobaatar

Sinobaatar is a genus of extinct mammal from the Lower Cretaceous of China. It is categorized within the also extinct order Multituberculata and among these it belongs to the plagiaulacid lineage (a possible infraorder). Sinobaatar was a small herbivore during the Mesozoic era, commonly called "the age of the dinosaurs". The genus was named by Hu Y. and Wang Y. in 2002. Three species have been described.

It has been found in Lower Cretaceous strata of the Yixian Formation in Liaoning, China. According to Hu & Wang (2002),

"[t]he dental features of Sinobaatar show again that eobaatarids are obviously intermediate between Late Jurassic multituberculates and the later forms".

Many Multituberculata are only known from teeth, but the type specimen of Sinobaatar is a reasonably complete skeleton.

Sinobaatar was eaten, at least on occasion, by the feathered dinosaur Sinosauropteryx prima (Hurum et al. 2006).

Sinocalliopteryx

Sinocalliopteryx (meaning 'Chinese beautiful feather') is a genus of carnivorous compsognathid theropod dinosaurs from the Lower Cretaceous Yixian Formation of China (Jianshangou Beds, dating to 124.6 Ma).

While similar to the related Huaxiagnathus, Sinocalliopteryx were larger. The type specimen, at 2.37 meters (7.78 ft) in length, in 2007 was the largest known compsognathid exemplar. In 2012 an even larger specimen was reported.

Tianyulong

Tianyulong (Chinese: 天宇龍; Pinyin: tiānyǔlóng; named for the Shandong Tianyu Museum of Nature where the holotype fossil is housed) was a genus of heterodontosaurid ornithischian dinosaur. The only species was T. confuciusi, whose remains were discovered in Jianchang County, Western Liaoning Province, China.

Timeline of paleontology

Timeline of paleontology

6th century B.C. — The pre-Socratic Greek philosopher Xenophanes of Colophon argues that fossils of marine organisms show that dry land was once under water.

1027 — The Persian naturalist, Avicenna, explains the stoniness of fossils in The Book of Healing by proposing the theory of petrifying fluids (succus lapidificatus).

1031-1095 — The Chinese naturalist, Shen Kuo, uses evidence of marine fossils found in the Taihang Mountains to infer geological processes caused shifting of seashores over time, and uses petrified bamboos found underground in Yan'an, to argue for gradual climate change.

1320-1390 — Avicenna's theory of petrifying fluids (succus lapidificatus) was elaborated on by Albert of Saxony.

c. 1500 — Leonardo da Vinci uses ichnofossils to complement his hypothesis concerning the biogenic nature of body fossils.

1665 — In his book Micrographia Robert Hooke compares petrified wood to wood, concludes that petrified wood formed from wood soaked in mineral-rich water, and argues that fossils like Ammonite shells were produced the same way, sparking debate over the organic origin of fossils and the possibility of extinction.

1669 — Nicholas Steno writes that some kinds of rock formed from layers of sediment deposited in water, and that fossils were organic remains buried in the process.

1770 — The fossilised bones of a huge animal are found in a quarry near Maastricht in the Netherlands. In 1808 Georges Cuvier identified it as an extinct marine reptile and in 1822 William Conybeare named it Mosasaurus.

1789 — The skeleton of a large animal is unearthed in Argentina. In 1796 Cuvier reports that it had an affinity to modern tree sloths and names it Megatherium.

1796 — Cuvier presents a paper on living and fossil elephants that shows that mammoths were a different species from any living elephant. He argues that this proved the reality of extinction, which he attributes to a geological catastrophe.

1800 — Cuvier writes that a drawing of a fossil found in Bavaria shows a flying reptile; in 1809 he names it Pterodactyl.

1808 — Cuvier and Alexandre Brongniart publish preliminary results of their survey of the geology of the Paris Basin that uses the fossils found in different strata to reconstruct the geologic history of the region.

1811 — Mary Anning and her brother Joseph discover the fossilised remains of an ichthyosaur at Lyme Regis.

1815 — William Smith published The Map that Changed the World, the first geologic map of England, Wales, and southern Scotland, using fossils to correlate rock strata.

1821 — William Buckland analyzes Kirkdale Cave in Yorkshire, containing the bones of lions, elephants and rhinoceros, and concludes it was a prehistoric hyena den.

1821-1822 — Mary Anning discovers the world's first Plesiosaur skeleton at Lyme Regis.

1822 — Mary Ann Mantell and Gideon Mantell discover fossil teeth of the dinosaur Iguanodon.

1822 — The editor of the French journal Journal de Phisique, Henri Marie Ducrotay de Blainville, invents the word "paleontologie" for the reconstruction of ancient animals and plants from fossils.

1823 — Buckland finds a human skeleton with mammoth remains at Paviland Cave on the Gower Peninsula, but at the time it is not accepted that this showed they coexisted.

1824 — Buckland finds lower jaw of the carnivorous dinosaur Megalosaurus.

1829 — Buckland publishes paper on work he and Mary Anning had done identifying and analyzing fossilized feces found at Lyme Regis and elsewhere. Buckland coins the term coprolite for them, and uses them to analyze ancient food chains.

1830 — The Cuvier–Geoffroy debate in Paris on the determination of animal structure

1831 — Mantell publishes an influential paper entitled "The Age of Reptiles" summarizing evidence of an extended period during which large reptiles had been the dominant animals.

1832 — Mantell finds partial skeleton of the dinosaur Hylaeosaurus.

1836 — Edward Hitchcock describes footprints (Eubrontes and Otozoum) of giant birds from Jurassic formations in Connecticut. Later they would be recognized as dinosaur tracks.

1841 — Anatomist Richard Owen creates a new order of reptiles, dinosauria, for animals: Iguanodon, Megalosaurus, and Hylaeosaurus, found by Mantell and Buckland.

1841 — The first global geologic timescale is defined by John Phillips based on the type of fossils found in different rock layers. He coins the term Mesozoic for what Mantell had called the age of reptiles.

1856 — Fossils are found in the Neander Valley in Germany that Johann Carl Fuhlrott and Hermann Schaaffhausen recognize as a human different from modern people. A few years later William King names Homo neanderthalensis.

1858 — The first dinosaur skeleton found in the United States, Hadrosaurus, is excavated and described by Joseph Leidy.

1859 — Charles Darwin publishes On The Origin of Species.

1861 — The first Archaeopteryx, skeleton is found in Bavaria, Germany, and recognized as a transitional form between reptiles and birds.

1869 — Joseph Lockyer starts the scientific journal Nature

1871 — Othniel Charles Marsh discovers the first American pterosaur fossils.

1874-77 — Marsh finds a series of Equid fossils in the American West that shed light on the Evolution of the horse.

1877 — The first Diplodocus skeleton is found near Cañon City, Colorado.

1891 — Eugene Dubois discovers fossils of Java Man (Homo erectus) in Indonesia.

1901 — Petroleum geologist W.W. Orcutt recovers first fossils from the La Brea Tar Pits in Southern California, a rich source of ice age mammal remains.

1905 — Tyrannosaurus rex is described and named by Henry Fairfield Osborn.

1909 — Cambrian fossils in the Burgess Shale are discovered by Charles Walcott.

1912 — Continental Drift is proposed by Alfred Wegener, leading to plate tectonics, which explained many patterns of ancient biogeography revealed by the fossil record.

1912 — Charles Dawson announces discovery of Piltdown Man in England, a hoax that would confuse paleoanthropology until the fossils were revealed as forgeries in 1953.

1912-15 — Spinosaurus is found in North Africa and is speculated to be the largest terrestrial predator that ever lived.

1920 — Andrew Douglass proposes dendrochronology (tree-ring dating).

1924 — Raymond Dart examines fossils of Taung Child, found by quarrymen in South Africa, and names Australopithecus africanus.

1944 — The publication of Tempo and Mode in Evolution by George Gaylord Simpson integrates paleontology into the modern evolutionary synthesis.

1946 — Reginald Sprigg discovers fossils of the Ediacaran biota in Australia. In the 1960s Martin Glaessner would show that they were pre-Cambrian.

1947 — Willard Libby introduces carbon-14 dating.

1953 — Stanley A. Tyler discovers microfossils in the gunflint chert formation of cyanobacteria that created pre-Cambrian stromatolites approximately 2 billion years ago.

1967 — Paul S. Martin proposes the overkill hypothesis, that the extinction of the Pleistocene megafauna in North America resulted from over hunting by Native Americans.

1972 — Niles Eldredge and Stephen Jay Gould propose punctuated equilibrium, claiming that the evolutionary history of most species involves long intervals of stasis between relatively short periods of rapid change.

1974 — Donald Johanson and Tom Gray discover a 3.5 million-year-old female hominid fossil that is 40% complete and name it "Lucy".

1980 — Luis Alvarez, Walter Alvarez, Frank Asaro, and Helen Michel propose the Alvarez hypothesis, that a comet or asteroid struck the Earth 66 million years ago causing the Cretaceous–Paleogene extinction event, including the extinction of the non-avian dinosaurs, and enriching the iridium in the K–T boundary.

1982 — Jack Sepkoski and David M. Raup publish a statistical analysis of the fossil record of marine invertebrates that shows a pattern (possibly cyclical) of repeated mass extinctions.

1984 — Hou Xianguang discovers the Maotianshan Shales Cambrian fossil site in the Yunnan province of China.

1993 — Johannes G.M. Thewissen and Sayed Taseer Hussain discover fossils of the amphibious whale ancestor Ambulocetus in Pakistan.

1996 — Li Yumin discovers a fossil of the theropod dinosaur Sinosauropteryx showing evidence of feathers in the Liaoning province of China.

2004 — Tiktaalik, a transitional form between lobe-finned fish and tetrapods is discovered in Canada by Ted Daeschler, Neil H. Shubin, and Farish A. Jenkins Jr..

2009 — Fossils of Titanoboa, a giant snake, are unearthed in the coal mines of Cerrejón in La Guajira, Colombia, suggesting paleocene equatorial temperatures were higher than today. "

2016 — Tail fossils of a baby species of Coelurosaur, fully preserved in amber including soft tissue, are found in Myanmar by Lida Xing.

Zhangheotherium

Zhangheotherium is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, Zhangheotherium, described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known from a complete skeleton. It was dated to between 145–125 million years ago in the Cretaceous. A single species, Zhangheotherium quinquecuspidens, is known.

Symmetrodonts and other archaic mammals such as multituberculates and monotremes are still being debated on their taxonomical relationships. Zhangheotherium has many primitive characteristics. Among them is a spur at the foot, seen today in the modern platypus. In addition, it walked with a reptilian sprawl, like Monotremes and many Mesozoic mammals such as Jeholodens and Repenomamus. Recent studies show that it led a possibly scansorial lifestyle, possessing long hindlimbs and a large plantar area on the foot, both optimal for climbing.The specimen GMV 2124 of the feathered dinosaur Sinosauropteryx? sp. contained two jaws of Zhangheotherium in its stomach region (Hurum et al. 2006). Thus, it seems to have preyed on this primitive mammal, possibly on a regular basis.

Coelurosauria

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