Rank Genus | Class Reptilia Phylum Chordata | |
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Similar Yangchuanosaurus, Sinraptor, Piatnitzkysaurus, Omeisaurus, Gasosaurus | ||
Szechuanosaurus remix
Szechuanosaurus ("Szechuan lizard") is a extinct genus of carnivorous theropod dinosaur from the Late Jurassic. Fossils referred to the genus have been found in Asia in the Oxfordian (Peng et al., 2005). Its type species is largely based on several undiagnostic teeth from the Shangshaximiao Formation.
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Szechuanosaurus sounds
Discovery and species
Three species have been assigned to this genus over the years. The type species is Szechuanosaurus campi, named by Yang Zhongjian ("Chung Chien Young") in 1942 for four isolated tooth specimens: IVPP V235, two partial teeth; IVPP V236, a partial tooth; IVPP V238, several tooth fragments; and IVPP V239, a single tooth. The teeth form a syntype series and were not found together. Also a very fragmentary skeleton, specimen UCMP 32102, was by Yang listed as part of the type material. Some of the teeth indicate a large body-size. These fossils, although possibly sinraptorid, are now considered to be non-diagnostic, making S. campi a nomen dubium. The generic name refers to Szechuan. The specific name honours the American paleontologist Charles Lewis Camp who had discovered UCMP 32102. S. campi is also sometimes reported to include Chienkosaurus ceratosauroides, although some researchers still believe that the latter may yet prove to be a distinct species.
A partial skeleton, CV 00214, was initially listed by Dong et al. (1978) in a faunal list as a new species of Szechuanosaurus, Szechuanosaurus yandonensis. At first, there was no description or illustration of it, making S. yandonensi at the time a nomen nudum. Later, Dong Zhiming et alii (1983) described it, and assigned it to Szechuanosaurus campi The affinities of this skeleton are uncertain, and it has only been briefly described. Holtz et al. (2004) included it in their phylogenetic analysis and found it to be the most basal tetanuran. This individual was a medium-sized theropod, with an ischium (a pelvic bone) of 420 millimetres (17 in); for comparison, an ischium of Piatnitzkysaurus estimated to weigh 504 kilograms (1,111 lb) is 423 millimetres (16.7 in) long. In 2000, Daniel Chure referred the specimen to "Szechuanoraptor dongi", itself an invalid nomen ex dissertatione. Carrano, Benson & Sampson (2012) synonymized it with Yangchuanosaurus shangyouensis from the same formation.
The third species is Szechuanosaurus zigongensis, named by Gao Yuhui in 1993 for an almost complete skeleton, specimen ZDM 9011. It is an older species, from the Middle Jurassic, appearing to be distinct from the type species and therefore requires its own genus name. It was reassigned to Yangchuanosaurus, as a Yangchuanosaurus zigongensis, by Matthew Carrano, Roger Benson & Scott Sampson in 2012.