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YANGCHUANOSAURUS

a meat-eating metriacanthosaurid theropod dinosaur from the Late Jurassic of China.
Pronunciation: yan-CHWAHN-o-SOR-us
Meaning: Yangchuan lizard
Author/s: Dong (1975)
Synonyms: See below
First Discovery: Sichuan, China
Chart Position: 199

Yangchuanosaurus shangyouensis

It warms the cockles of our heart when untrained-in-science but nevertheless hard working individuals unearth ground-breaking fossils by accident and manage not to smash them to bits, so caps off to labourers carrying out repair work on the Shangyou Reservoir Dam in China's Yongchuan District, who discovered the first fossils of Yangchuanosaurus after a storm in 1976.

Yangchuanosaurus, although a relative of Allosaurus, was smaller and less famous than its North American counterpart, but at over ten meters long and close to three tons in weight it was hardly meek and mild. Specifically a sinraptorid, the biggest sinraptorid, and one of the biggest Jurassic theropods from the whole of Asia, it would have found the noodle-necks of the contemporaneous sauropods Mamenchisaurus and Omeisaurus irresistable, from a dining point of view.

One of the most striking features of Yangchuanosaurus is a deep and robust but extremely lightweight skull due to six pairs of fenestrae or windows. This was a natural feature and not a side effect of the dynamite needed to blast it from its rocky tomb, and gave it a much lighter head than similar sized Theropods, even taking a bony nose knob, horny bits and possible keratine "mask" into account.

In 1988 Greg Paul sank Yangchuanosaurus into Metriacanthosaurus, Currie and Zhou moved a second species—Yangchuanosaurus hepingensis—to Sinraptor hepingensis in 1994, and in 1999 Gao Yuhui moved it back again along with all other specimens of Sinraptor which he regarded, on the whole, as synonymous with Yangchuanosaurus. Of that moving and shaking, only Currie and Zhao were taken seriously by palaeontologists, but Gao eventually managed to expand Yangchuanosaurus with another species, indirectly, when Matt Carrano moved his Szechuanosaurus zigongensis there in 2012!
Etymology
Yangchuanosaurus is derived from "Yongchuan" (for Yongchuan county, its place of discovery) and the Greek "sauros" (lizard). The Shangyou dam is honored in the species epithet, shangyouensis, which means "from Shangyou" in Latin.
Discovery
The first fossils of Yangchuanosaurus were discovered in the dark-red sandy mudstones of the Chongqing Group's Upper Shaximiao (Shangshaximiao) Formation, 350 m from the base of the Daba Dam at Shangyou Reservoir, Yongchuan County, China, by Sinung Chen, the leader of the Daba Reconstruction Public Works Corps, in July of 1976, and excavated by Yihong Zhang and Fanmo Ceng of the Chungking Museum of Natural History. The holotype (CV00215) is an almost complete skeleton barring the forelimbs and a few vertebrae. The skull measures 82 cm long and 50 cm high.
Estimations
Timeline:
Era: Mesozoic
Epoch: Late Jurassic
Stage: Oxfordian
Age range: 162-156 mya
Stats:
Est. max. length: 11 meters
Est. max. hip height: 3 meters
Est. max. weight: 3.5 tons
Diet: Carnivore
Family Tree:
Dinosauria
Saurischia
Theropoda
Tetanurae
Carnosauria
Sinraptoridae
Yangchuanosaurus
shangyouensis
Other species
Yangchuanosaurus zigongensis ("from Zigong") was originally named Szechuanosaurus zigongensis by Gao in 1993 based on an almost complete skeleton (holotype ZDM 9011, plus ZDM 9012, ZDM 9013 and ZDM 9014) from the Dashanpu Dinosaur Quarry of Zigong, Sichuan, then he named it again in a 1998 paper as if it was an all new critter! Chure 2001 believed that these fossils belonged to Szechuanoraptor dongi—a name he coined in 2001 for remnants which were originally known as Szechuanosaurus "yandonensis". Lacking similarities and being from the much older Middle Jurassic lower Shaximiao (Xiashaximiao) Formation, these remains were used to anchor a new species of YangchuanosaurusYangchuanosaurus zigongensis—by Carrano in 2012. This is the only other species of Yangchuanosaurus that is classed as valid.
Yangchuanosaurus hepingensis ("from Heping") was discovered in the Upper Shaximiao (Shangshaximiao) Formation about 1 km north of the Zigong Train Station by He Geyin, Wang Fucheng and other farmers from Heping in February of 1985. It was named by Gao Yuhui in 1992 but became a second species of SinraptorSinraptor hepingensis—when Currie and Zhao named Sinraptor dongi in 1994. In 1999, Gao figured that by synonomising Sinraptor with Yangchuanosaurus not only would he get his Yangchuanosaurus hepingensis back he would also add a fourth species—Yangchuanosaurus dongi—to the Yangchuanosaurus stable. Unfortunately (for him!) almost no-one took his revenge-sinking seriously. In 2009, Lida Xing re-described a shoulder blade of the holotype (ZDM 0024) that he surmised had been damaged in a violent collision, perhaps with the swinging tail club of the sauropod Mamenchisaurus hochuanensis.
Yangchuanosaurus magnus ("Great") was named by Dong, Zhou, and Zhang in 1983, simply for being the largest specimen of Yangchuanosaurus ever discovered (the skull measures 111 cm long and 65 cm high). According to Carrano et al, size is pretty much the only difference between Yangchuanosaurus magnus and Yangchuanosaurus shangyouensis, and no grounds to keep them separate, which is what most paleontologists have always thought. It's based on #CV00216 (a weathered skull and partial skeleton consisting mainly of vertebrae and hip bones but not much in the way of limbs) that was discovered while digging foundations for the Hongjiang Machine Factory in Yongchuan in September of 1973, and was excavated by Li Xuanmin, Zhou Shiwu, and Lan Dongyao of the Chungking Museum of Natural History.
Synonyms
Yangchuanosaurus shangyouensis:
Yangchuanosaurus magnus (Dong, Zhou & Zhang, 1983)
Szechuanosaurus yandonensis (Dong et al., 1978)
Szechuanoraptor dongi (Chure, 2001)
Yangchuanosaurus zigongensis:
Szechuanosaurus zigongensis (Gao, 1993)
References
• Dong Z (1975) "A new carnosaur from Yongchuan County, Sichuan Province". Ke Xue Tong Bao [Science Newsletter] 23 (5): 302–04.
• Dong Z, Zhou S and Zhang Y (1983) "Dinosaurs from the Jurassic of Sichuan". Palaeontologica Sinica, New Series C. 162 (23): 1–136.
• Paul G S (1988) "Eustreptospondylids and Metriacanthosaurs" in "Predatory Dinosaurs of the World: A Complete Illustrated Guide".
• Gao Y (1992) "Yangchuanosaurus hepingensis - a new species of carnosaur from Zigong, Sichuan, China". Vertebrata PalAsiatica 30(4): 313-324.
• Gao Y (1993) "A new species of Szechuanosaurus from the Middle Jurassic of Dashanpu, Zigong, Sichuan". Vertebrata PalAsiatica 31(4): 308-314.
• Currie P J and Zhao X-J (1994) "A new carnosaur (Dinosauria, Theropoda) from the Jurassic of Xinjiang, People's Republic of China". Canadian Journal of Earth Sciences 30(10-11): 2037-2081.
• Gao Y (1998) "A new species of Middle Jurassic Carnosauria from Dashanpu, Zigong, Sichaun Province, Szechuanosaurus zigongensis sp. nov.". Vertebrata PalAsiatica 31(4): 308-314.
• Gao Y (1999) "A complete carnosaur skeleton from Zigong, Sichuan". Sichuan Science and Technology Press, Chengdu 1-100 [in Chinese with English summary].
• Xing L-D, Dong H, Peng G-Z, Shu C-K, Hu X-D and Jiang H (2009) "
A scapular fracture in Yangchuanosaurus hepingensis (Dinosauria: Theropoda)". Geological Bulletin of China 28(10): 1390-1395.
• Paul G S (2010) "The Princeton Field Guide to Dinosaurs".
• Carrano M T, Benson R B J and Sampson S D (2012) "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology 10(2): 211.
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To cite this page:
Atkinson, L. "YANGCHUANOSAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 21st Sep 2017.
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