""Yangchuanosaurus"" is an extinct genus of metriacanthosaurid theropod dinosaur that lived in China during the late Oxfordian stage of the Late Jurassic, and was similar in size and appearance to its North American contemporary, "Allosaurus". It hails from the Upper Shaximiao Formation and was the largest predator in a landscape which included the sauropods "Mamenchisaurus" and "Omeisaurus" as well as the Stegosaurs "Chialingosaurus", "Tuojiangosaurus" and "Chungkingosaurus". It got its name after its discovery site in Yongchuan, in China.
The type specimen of "Y. shangyouensis" had a skull 82 cm long, and its total body length was estimated at about 8 m. Another specimen, assigned to the new species "Y. magnus", was even larger, with a skull length of 1.11 m. It may have been up to 10.8 m long, and weighed as much as 3.4 MT. There was a bony ridge on its nose and multiple hornlets and ridges, similar to "Ceratosaurus".
"Yangchuanosaurus" was a large, powerful meat-eater. It walked on two large, muscular legs, had short arms, a strong, short neck, a big head with powerful jaws, and large, serrated teeth. It had a long, massive tail that was about half of its length. Its feet had three toes, each with a large claw. Its arms were short, and it had three clawed fingers on each hand.
Dong "et al." 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 or the early Kimmeridgian stage of the Late Jurassic period, about 161.2-154 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." on the basis of CV 00216, another complete skull and skeleton. A detailed revision of tetanuran phylogeny by Carrano, Benson & Sampson revealed that both species are cospecific. Dong "et al." and Dong "et al." differentiated these species primarily on the basis of size. In addition, Dong "et al." 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." matrix. Gregory S. Paul regarded this genus as the same as "Metriacanthosaurus", but this has not been supported.
Carrano "et al." 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." 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." described it, and assigned it to "Szechuanosaurus campi", a dubious species which is known only from 4 teeth. Carrano "et al." noted that CV 00214 can't be assigned to "S. campi" because the holotype materials of "S. campi" are non-diagnostic and no teeth are preserved in CV 00214. A recent restudy of CV 00214 by Daniel Chure concluded that it represented a new taxon, informally named "Szechuanoraptor dongi", into which "Szechuanosaurus zigongensis" should also be subsumed. However, the most recent revision ) suggested that CV 00214 and "S." "zigongensis" can't be cospesific 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 ...
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