Austrocheirus
Temporal range: Cenomanian
~96.2 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Genus: Austrocheirus
Ezcurra et al., 2010
Species:
A. isasii
Binomial name
Austrocheirus isasii
Ezcurra et al., 2010

Austrocheirus is an extinct genus of theropod dinosaur, possibly a neoceratosaurian, which existed during the Late Cretaceous period. It was named and described by Martín Ezcurra, Federico Agnolin and Fernando Novas in 2010. It contains the type species Austrocheirus isasii. The generic name means "southern hand". The specific epithet honours discoverer and preparator Marcelo Pablo Isasi.[1]

The fossils were found on 17 March 2002 in the Pari Aike Formation, which was originally dated to the Maastrichtian, around 71 to 66 million years ago, but was more recently dated to the Cenomanian, around 96.2 million years ago.[2] These fossils consist of a partial manus (hand), a tibia, axial bones, and a foot bone.[1]

In 2016, its length was estimated to be 5.5 metres (18 ft).[3]

A cladistic analysis indicated Austrocheirus had a basal position in the Abelisauroidea, but was more derived than Ceratosaurus and Berberosaurus. This would make it the first known mid-sized abelisauroid which did not possess the reduced forelimbs seen in other members of that clade.[1]

The referral of Austrocheirus to Abelisauroidea was challenged by Oliver Rauhut (2012), who claimed that the putative abelisauroid synapomorphies used to justify this referral are actually also present in the skeletons of non-abelisauroid theropods. Thus, according to Rauhut Austrocheirus can be only classified as a theropod dinosaur of uncertain phylogenetic placement.[4]

See also

References

  1. ^ a b c Ezcurra, M.D.; Agnolin, F.L. & Novas, F.E. (2010). "An abelisauroid dinosaur with a non-atrophied manus from the Late Cretaceous Pari Aike Formation of southern Patagonia" (PDF). Zootaxa. 2450: 1–25. doi:10.11646/zootaxa.2450.1.1.
  2. ^ Varela, A. N.; Poiré, D. G.; Martin, T.; Gerdes, A.; Goin, F. J.; Gelfo, J. N.; Hoffmann, S. (2012). "U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: Its relationship with the evolution of the Austral Basin". Andean Geology. 39 (3): 359–379. doi:10.5027/andgeoV39n3-a01.
  3. ^ Grillo, O. N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. doi:10.1016/j.cretres.2016.09.001.
  4. ^ Oliver W.M. Rauhut (2012). "A reappraisal of a putative record of abelisauroid theropod dinosaur from the Middle Jurassic of England". Proceedings of the Geologists' Association. in press (5): 779–786. doi:10.1016/j.pgeola.2012.05.008.