Biology:Yangchuanosaurus
| Yangchuanosaurus | |
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| Y. shangyouensis skeleton displayed in Hong Kong Science Museum | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Metriacanthosauridae |
| Genus: | †Yangchuanosaurus Dong et al., 1978 |
| Type species | |
| †Yangchuanosaurus shangyouensis Dong et al., 1978
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| Other species | |
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| Synonyms | |
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Synonyms of Y. shangyouensis
Synonyms of Y. zigongensis
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Yangchuanosaurus is an extinct genus of metriacanthosaurid theropod dinosaur that lived in China from the Middle Jurassic to Early Cretaceous periods (Bathonian to Berriasian stages), and was similar in size and appearance to its North American and European relative, Allosaurus. Yangchuanosaurus hails from the Upper Shaximiao Formation and Suining Formation and was the largest predator in a landscape that included the sauropods Mamenchisaurus and Omeisaurus and the stegosaurs Chialingosaurus, Tuojiangosaurus and Chungkingosaurus. This theropod was named after the area in which was discovered, Yongchuan, in China.
Discovery and species
Dong et al. (1978) named Yangchuanosaurus shangyouensis on the basis of CV 00215, a complete skull and skeleton which was collected from the Shangshaximiao Formation, near Yongchuan, Yongchuan District, Sichuan. It dates to the Oxfordian stage of the Late Jurassic period, about 161.2 to 157.3 million years ago. It was discovered in June 1977 by a construction worker during the construction of the Shangyou Reservoir Dam. A second species from the same locality, Y. magnus, was named by Dong et al. (1983) on the basis of CV 00216, another complete skull and skeleton. A detailed revision of tetanuran phylogeny by Carrano, Benson & Sampson (2012) revealed that both species are conspecific. Dong et al. (1978) and Dong et al. (1983) differentiated these species primarily on the basis of size. In addition, Dong et al. (1983) noted that the maxilla of Y. magnus has an additional fenestra within the antorbital fossa, whereas Y. shangyouensis possessed only a fossa in this location. However, it is considered to be an intraspecific, possibly ontogenetic, variation. Furthermore, the apparent difference in cervical vertebral morphology can be explained by comparing different positions within the column. Hence, the holotypes of the two species of Yangchuanosaurus are effectively identical, and their codings are identical in Carrano et al. (2012) matrix.[1] Gregory S. Paul (1988) regarded this genus as a synonym of Metriacanthosaurus, but this has not been supported.[2]
Carrano et al. (2012) assigned a third specimen to Y. shangyouensis. CV 00214 is represented by a partial postcranial skeleton lacking the skull. It was collected in the Wujiaba Quarry, near Zigong city, Sichuan, from the lower part of the Shangshaximiao Formation. CV 00214 was initially listed by Dong et al. (1978) in a faunal list as a new species of Szechuanosaurus, Szechuanosaurus "yandonensis". There is no description or illustration of it, making S. "yandonensis" a nomen nudum. Later, Dong et al. (1983) described it, and assigned it to Szechuanosaurus campi, a dubious species which is known only from four teeth. Carrano et al. (2012) noted that CV 00214 can't be assigned to S. campi because the holotype materials of S. campi (IVPP V.235, V.236, V.238, V.239; teeth) are non-diagnostic and no teeth are preserved in CV 00214. A recent restudy of CV 00214 by Daniel Chure (2001) concluded that it represented a new taxon, informally named "Szechuanoraptor dongi", into which Szechuanosaurus zigongensis should also be subsumed. However, the most recent revision (by Carrano et al. (2012)) suggested that CV 00214 and "S." zigongensis cannot be cospecific as there are no autapomorphies shared between them, and the latter derives from the underlying Xiashaximiao Formation. A phylogenetic analysis found CV 00214 to be most closely related to Y. shangyouensis, and thus the former is assignable to it. Furthermore, Szechuanosaurus zigongensis was found to be closely related to Y. shangyouensis and therefore was designated as the second species of Yangchuanosaurus.[1]
Yangchuanosaurus zigongensis is known from four specimens including ZDM 9011 (holotype), a partial postcranial skeleton; ZDM 9012, a left maxilla; ZDM 9013, two teeth and ZDM 9014, a right hind limb. It was first described by Gao (1993), and all specimens were collected from the Middle Jurassic Xiashaximiao Formation in the Dashanpu Dinosaur Quarry of Zigong, Sichuan.[3]
A third, informal species, Yangchuanosaurus "longqiaoensis", was briefly mentioned in a faunal listing of the Penglaizhen Formation (initially believed to date to the Late Jurassic but is probably Early Cretaceous (Berriasian – Valanginian) in age)[4] by Li, Zhang and Cai (1999).[5] However, since it was published solely in a faunal list and not described in detail, it is a nomen nudum and is questionably referable to Yangchuanosaurus.[6]
Remains assigned to Yangchuanosaurus sp. were recovered from the Berriasian Suining Formation in 1966.[7]
Description
The type specimen of Y. shangyouensis had a skull 82 centimeters (2.69 ft) long, and its total body length was estimated at 8 meters (26 ft).Cite error: Closing </ref> missing for <ref> tag
| Allosauroidea |
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References
- ↑ 1.0 1.1 Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology 10 (2): 211–300. doi:10.1080/14772019.2011.630927. Bibcode: 2012JSPal..10..211C.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedpaul-88 - ↑ Gao, Y. (1993). A new species of Szechuanosaurus from the Middle Jurassic of Dashanpu, Zigong, Sichuan. Vertebrata PalAsiatica 31(4): 308-314.
- ↑ Huang, Diying (January 1, 2019). "Jurassic integrative stratigraphy and timescale of China" (in en). Science China Earth Sciences 62 (1): 223–255. doi:10.1007/s11430-017-9268-7. ISSN 1869-1897. Bibcode: 2019ScChD..62..223H. https://doi.org/10.1007/s11430-017-9268-7.
- ↑ Li; Zhang; Cai (1999). "The Characteristics of the Composition of the Trace Elements in Jurassic Dinosaur Bones and Red Beds in Sichuan Basin.". Geological Publishing House, Beijing: 155.
- ↑ "Neotheropoda". https://www.theropoddatabase.com/Neotheropoda.htm#Yangchuanosauruslongqiaoensis:~:text=Yangchuanosaurus?%20%22longqiaoensis,Beijing.%20155%20pp..
- ↑ He, X.; Yang, S.; Cai, K.; Li, K.; Liu, Z. (1996). "A new species of sauropod, Mamenchisaurus anyuensis sp. nov.". Papers on Geosciences Contributed to the 30th International Geological Congress: 83–86.
- Dong Zhiming (1988). Dinosaurs from China. China Ocean Press, Beijing & British Museum (Natural History). ISBN 0-565-01073-5.
- Dong Zhiming (1992). Dinosaurian Faunas of China. China Ocean Press, Beijing. ISBN 3-540-52084-8.
- Fantastic Facts About Dinosaurs (ISBN:0-7525-3166-2)
Wikidata ☰ Q131131 entry
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