Metriacanthosauridae is an extinctfamily of allosauroidtheropoddinosaurs that lived from the Middle Jurassic to the Early Cretaceous.[2] When broken down into its Greek roots, it means "moderately-spined lizards". The family is split into two subgroups: Metriacanthosaurinae, which includes dinosaurs closely related to Metriacanthosaurus, and another group composed of the close relatives of Yangchuanosaurus. Metriacanthosaurids are considered carnosaurs, belonging to the Allosauroidea superfamily. The group includes species of large range in body size. Of their physical traits, most notable are their neural spines.[3] The records of the group are mostly confined to Asia, though Metriacanthosaurus is known from Europe. Metriacanthosauridae is used as a senior synonym of Sinraptoridae.
Furthermore, the 2012 study named a new subfamily Metriacanthosaurinae to include all metriacanthosaurids more closely related to Metriacanthosaurus than to Yangchuanosaurus. A much larger phylogenetic analysis found Xuanhanosaurus, previously considered a basal megalosauroid, to be the basalmost metriacanthosaurid.[6] Both Poekilopleuron and Lourinhanosaurus were recovered outside the family, and many taxa within the Metriacanthosauridae were in polytomy. However, the positions of Xuanhanosaurus and Poekilopleuron were very unstable, and their exclusion from the analysis gave a more resolved and stable cladogram. The cladogram presented here follows that study.[2]
Metriacanthosauridae fossils have only been found in modern Europe and Asia, parts of the prehistoric landmass Laurasia. From those found in Asia, most are from China, with a few discoveries in Thailand and other Asian countries.[clarification needed] The group is thought to have originated in Asia and spread westward to Europe. Yangchuanosaurus has only been found in Yangchuan, Sichuan, China.[citation needed]Metriacanthosaurus has been found in the Oxford Clay in Southern England. Similar to Yangchuanosaurus, Sinraptor has been found in Sichuan, but also in Xinjiang.[citation needed] In 2008, Xu and Clarke described a large tooth found in the Junggard Basin in Xinjian, China, belonging to a large sinraptorid.[7] The Late Jurassic Qigu Formation in Xinjiang has also yielded evidence of metriacanthosaurid habitation in the form of sauropod bones with bitemarks most likely belonging to a metriacanthosaurid.[8]Siamotyrannus has been found exclusively in Thailand. Shidaisaurus has been found in Yunnan, China.[citation needed] Fragmentary remains of allosauroids from the late Middle-early Late Jurassic Marnes de Dives in northern France bear close similarities to metriocanthosaurids, and may belong to members of the group.[9]
^Bailey, Jack Bowman. "Neural Spine Elongation in Dinosaurs: Sailbacks or Buffalo-Backs?" Journal of Paleontology, vol. 71, no. 06, 1997, pp. 1124–1146., doi:10.1017/s0022336000036076.
^Xu, X., and J. M. Clark. "The Presence of a Gigantic Theropod in the Jurassic Shishugou Formation, Junggar Basin, Western China." Vertebrata PalAsiatica, 46: 158–160. www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200811/W020090813369286986655.pdf *[1].
^Augustin, Felix J.; Matzke, Andreas T.; Maisch, Michael W.; Pfretzschner, Hans-Ulrich (2020). "A theropod dinosaur feeding site from the Upper Jurassic of the Junggar Basin, NW China". Palaeogeography, Palaeoclimatology, Palaeoecology. 560: 109999. Bibcode:2020PPP...560j9999A. doi:10.1016/j.palaeo.2020.109999. S2CID225210438.
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