Yangchuanosaurus: Difference between revisions

Dong ''et al.'' (1978) named ''Yangchuanosaurus shangyouensis'' on the basis of [[Municipal Museum of Chongqing|CV]]&nbsp;00215, a complete [[skull]] and [[skeleton]] which was collected from the [[Shangshaximiao Formation]], near Yongchuan, [[Yongchuan District]], [[Sichuan]]. It dates to the [[Oxfordian (stage)|Oxfordian]] stage of the [[Late Jurassic]] [[geological timescale|period]], about 161.2 to 157.3&nbsp;[[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&nbsp;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]], [[individual variation|variation]]. Furthermore, the apparent difference in [[Cervical vertebrae|cervical vertebra]]l 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.<ref name=tetanurans2012>{{Cite journal | last1 = Carrano | first1 = M. T. | last2 = Benson | first2 = R. B. J. | last3 = Sampson | first3 = S. D. | doi = 10.1080/14772019.2011.630927 | title = The phylogeny of Tetanurae (Dinosauria: Theropoda) | journal = Journal of Systematic Palaeontology | volume = 10 | issue = 2 | pages = 211–300| year = 2012 | bibcode = 2012JSPal..10..211C | s2cid = 85354215 }}</ref> [[Gregory S. Paul]] (1988) regarded this genus as a synonym of ''[[Metriacanthosaurus]]'', but this has not been supported.<ref name="paul-88" />