Quilmesaurus
| Quilmesaurus Temporal range: Late Cretaceous | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Theropoda |
| Family: | †Abelisauridae |
| Tribe: | †Carnotaurini |
| Genus: | †Quilmesaurus Coria, 2001 |
| Type species | |
| Quilmesaurus curriei Coria, 2001 | |
Quilmesaurus is a genus of carnivorous theropod dinosaur from the Patagonian Upper Cretaceous (Campanian stage) of Argentina.
During the late 1980s, a field crew from the Universidad Nacional Tucumán, lead by Jaime Powell, uncovered forty kilometres south of Roca City, in Río Negro province, northern Argentina, the remains of a theropod near the Salitral Ojo de Agua.
In 2001, Rodolfo Aníbal Coria named and described the type species Quilmesaurus curriei. The genus name is derived from the Quilme, a Native American people, and the specific name honours Dr. Philip John Currie, a Canadian theropod specialist.[1]
The holotype, MPCA-PV-100, part of the collection of the Museo Provincial "Carlos Ameghino", consists of the distal, lower, half of the right femur, thighbone, and a complete right tibia, shinbone, collected from the Allen Formation, Malarge Group, Neuquén Basin, dating from the Campanian-Maastrichtian. The specimen came from the fluvial sandstones at the bottom of the Allen Formation. The taxon is notable as one of the youngest records of a non-avian theropod from Patagonia.
Quilmesaurus is estimated to have measured five to six meters (sixteen to twenty feet) in length.
Quilmesaurus curriei is distinguished by a highly specialized knee joint. The femur possess a strong, well-developed mediodistal crest, and the tibia has a hooked cnemial crest. There is evidently no fusion of the proximal tarsals, and the lateral maleus of the lower tibia projects twice as much as the internal maleus, presenting an asymmetrical profile.
Coria in 2001 placed Quilmesaurus in a general Theropoda. The presence of a notch in the distal articular surface of the tibia was cited by him as evidence of a possible relationship with basal Tetanurae, which would be surprising as Quilmesaurus lived during a time when South American theropod assemblages were dominated by abelisaurids and carcharodontosaurs. Other theropod material has been recovered from within these same strata and has in 2005 also provisionally been referred to the Tetanurae.[2] However, in 2004 Rubén Juárez Valieri e.a. concluded that Quilmesaurus, in view of the hatchet-shaped cnemial crest, was a member of the Abelisauridae.[3] In 2007 a subsequent study found that Quilmesaurus more precisely belonged to the Carnotaurinae, as shown by the pending lobe of that crest. Juárez Valieri was unable to establish a single autapomorphy of the taxon, concluding that Quilmesaurus were a nomen vanum.[4]
Other dinosaur remains recovered from the Allen Formation include titanosaurs (Aeolosaurus), a lambeosaurine hadrosaur, a nodosaurid, and dinosaur eggs.
References
- ↑ Coria, R.A. 2001. "A new theropod from the Late Cretaceous of Patagonia". In: Tanke, D.H. et Carpenter, K. (eds). 2001. Mesozoic Vertebrate Life, Indiana University Press, pp 3-9
- ↑ Coria, R.A. & Salgado, L. 2005. "Last Patagonian theropods". In: Carpenter, K. 2005. The Carnivorous Dinosaurs, Indiana University Press, pp 153-160
- ↑ Juárez Valieri R.D, Fiorelli L.E. and Cruz, L.E. 2004. "Quilmesaurus curriei Coria, 2001. Su validez taxonómica y relaciones filogenéticas". XX Jornadas Argentinas de Paleontología de Vertebrados (La Plata), Resúmenes, p. 36-37
- ↑ Juárez Valieri, R.D.; Fiorelli, L.E. y Cruz, L.E., 2007, "Quilmesaurus curriei Coria, 2001. Su validez taxonómica y relaciones filogenéticas", Revista del Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” – Paleontología, 9(1): 59-66