Temporal range: Middle Jurassic-Early Cretaceous, 175.6–135 Ma
|Sinraptor dongi, Royal Tyrrell Museum|
Metriacanthosauridae is an extinct family of carnivorous allosauroid theropod dinosaurs. They tended to be large predators, some growing to sizes of 10 metres (33 ft). Metriacanthosaurids are carnosaurs, and many were initially classified within Megalosauridae or Allosauridae. A gigantic tooth belonging to what most likely is a giant sinraptorid has been described by Xu and Clarke in 2008.
- A short or absent anterior ramus of the maxilla (also found in Carcharodontosaurids and Piatnitzkysaurids).
- The laterosphenoid articulated on the frontal and postorbital.
- A squamosal without constriction of the lower temporal fenestra. (also found in megalosauroids)
- A flange on the squamosal covering the quadrate head laterally.
- A well-defined longitudinal groove on the lateral side of the dentary housing a row of neurovascular foramina.
- Broad, well developed spinopostzygapophyseal lamina on the axis.
- A manus shorter than the forearm.
- Subrectangular and sheet-like neural spines of middle caudal vertebrae.
- A manus without digit V or the phalanges of digit IV (also found in Neovenatorids).
- A heart-shaped cross section of the ilium's paired midshafts (also found in Coelophysids).
- Fused distal end of the ischium (also found in Neovenatorids and basal tetanurans).
Metriacanthosaurines share the following synapomorphies among metriacanthosaurids:
- The anteroventral border of the maxillary antorbital fenestra being demarcated by a raised ridge (also found in Eoraptor, Coelophysids, Masiakasaurus, Marshosaurus, and Compsognathus).
- A pronounced ventral keel on the anterior dorsal vertebrae (also found in Condorraptor, Piatnitzkysaurus, Carcharodontosaurus and many megalosaurians).
- A straight posterior margin of the iliac postacetabular process.
- The angle between the long axes of the pubic shaft and boot being less than 60 degrees.
- A ventrally curved ischial shaft (also found in Coelophysids, Eustreptospondylus, Afrovenator, Megalosaurus and Compsognathus).
- A bulbous fibular crest on the tibia (also found in 'Dilophosaurus' sinensis).
Cladistically, Sinraptoridae was latest defined in 2005 by Paul Sereno as the most inclusive monophyletic group that contains Sinraptor dongi and all species closer related to Sinraptor than to either Allosaurus fragilis, Carcharodontosaurus saharicus, or the house sparrow (Passer domesticus).
Carrano, Benson & Sampson (2012) noted that the name Metriacanthosauridae should be used as it has priority over Sinraptoridae. Furthermore, they named a new subfamily Metriacanthosaurinae to include all metriacanthosaurids more closely related to Metriacanthosaurus than to Yangchuanosaurus. A much larger phylogenetic analysis found the basal megalosauroid Xuanhanosaurus (according to Benson et al., 2010) as the basalmost metriacanthosaurid. Both Poekilopleuron and Lourinhanosaurus were recovered outside the family, and many taxa within the Metriacanthosauridae were in polytomy. However, the position of Xuanhanosaurus and Poekilopleuron is very unstable, and their exclusion from the analysis gave more resolved and stable cladogram. The cladogram presented here follows that study.
- Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 10 (2): 211–300. doi:10.1080/14772019.2011.630927.
- Xu, X., Clark, J.M. (2008): The presence of a gigantic theropod in the Jurassic Shishugou Formation, Junggar Basin, western China. Vertebrata PalAsiatica, 46: 158-160. http://www.ivpp.cas.cn/xscbw/xsqk/gjzdwxb/xbwzxz/200811/W020090813369286986655.pdf
- Sereno, Paul. "Sinraptoridae". Taxon Search. Retrieved 12 December 2010.
- Benson, R.B.J., Carrano, M.T and Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic". Naturwissenschaften. 97 (1): 71–78. Bibcode:2010NW.....97...71B. doi:10.1007/s00114-009-0614-x. PMID 19826771. Supporting Information
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