''Austrocheirus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of theropod dinosaur, possibly a neoceratosaurian, which existed during the Late Cretaceous period. It was named and described by Martin Ezcurra, Federico Agnolin and Fernando Novas in

2010 File:2010 Events Collage New.png, From top left, clockwise: The 2010 Chile earthquake was one of the strongest recorded in history; The Eruption of Eyjafjallajökull in Iceland disrupts air travel in Europe; A scene from the opening ceremony of ...

. It contains the type species ''Austrocheirus isasii''. The generic name means "southern hand". The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

honours discoverer and preparator Marcelo Pablo Isasi. The fossils were found on 17 March 2002 in the

Pari Aike Formation The Cerro Fortaleza Formation, in older literature described as Pari Aike Formation, is a Late Cretaceous geologic formation of Campanian to Maastrichtian age (although it has formerly been reported to be Cenomanian to Santonian)Varela et al., 20 ...

, which was originally dated to the Maastrichtian, around 71 to 66 million years ago, but was more recently dated to the

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

, around 96.2 million years ago. However, this strata is now believed to date to the Campanian. These fossils consist of a partial manus (hand), a tibia, axial bones, and a foot bone. In 2016, its length was estimated to be . In 2012 Holtz estimated it at 6.5 meters (24 feet), while in 2016 Molina-Pérez & Larramendi gave a higher estimation at 9.3 meters (30.5 feet) in length and 1 tonne (1.1 short tons) in weight. A cladistic analysis indicated ''Austrocheirus'' had a basal position in the

Abelisauroidea Abelisauroidea is typically regarded as a Cretaceous group, though the earliest abelisauridae remains are known from the Middle Jurassic of Argentina (classified as the species Eoabelisaurus mefi) and possibly Madagascar (fragmentary remains of ...

, but was more derived than '' Ceratosaurus'' and ''

Berberosaurus ''Berberosaurus'' (meaning " Berber lizard", in reference to the Berbers of Morocco) is a genus of neotheropod dinosaur, possibly a ceratosaur, from the Early Toarcian-age (Lower Jurassic) Azilal Formation found in the High Atlas of Toundoute, Ou ...

''. This would make it the first known mid-sized abelisauroid which did not possess the reduced forelimbs seen in other members of that clade. 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.

References

Ceratosaurs Late Cretaceous dinosaurs of South America Cenomanian life Cretaceous Argentina Fossils of Argentina Fossil taxa described in 2010 Taxa named by Fernando Novas {{Cretaceous-reptile-stub

See also

References