Zupaysaurus
| Zupaysaurus Temporal range: Late Triassic to Early Jurassic
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| Restoration in resting pose, based on possible dilophosaurid trace fossil | |
Scientific classification 
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| Missing taxonomy template (fix): | Zupaysaurus rougieri |
Zupaysaurus (/[invalid input: 'icon']ˌzuːpeɪˈsɔːrəs/; "devil lizard") is a genus of early theropod dinosaur living during the Rhaetian stage of the Late Triassic to Hettangian stage of the Early Jurassic of what is now Argentina. Although a full skeleton has not yet been discovered, Zupaysaurus can be considered a bipedal predator, up to 4 meters (13 ft) long. It may have had two parallel crests running the length of its snout.
Description
Zupaysaurus was a medium-sized theropod. An adult skull measured approximately 45 centimeters (18 in) in length, indicating a body length of approximately 4 meters (13 ft) from snout to tail tip. Like all known theropods, Zupaysaurus walked only on its hindlegs, leaving the forelimbs free to grasp its prey. A small gap separated the teeth of the premaxillary and maxillary bones of the upper jaw, and the astragalus and calcaneum bones of the ankle were fused together, as seen in many early theropods.[1]
As Zupaysaurus was originally described, the skull bore two thin parallel crests on top of the skull, similar to other theropods like Dilophosaurus and Megapnosaurus (Syntarsus) kayentakatae. These crests were allegedly formed by the nasal bones solely, unlike those of many other theropods which also incorporated the lacrimal. Crests on the skull were pervasive among theropods and may have been used for communicative purposes such as species or gender recognition.[2] However, more recent analysis of the skull has cast doubt on the presence of these crests in Zupaysaurus. An unpublished abstract presented at a recent conference indicated the structures initially identified as crests were in fact the lacrimal bones displaced upwards during the process of fossilization.[3]
Taxonomy
The name Zupaysaurus is composed of the Quechua word zupay ("devil") and the Greek word σαυρος ("lizard"). The type species has been named Z. rougieri after Guillermo Rougier, the scientist who led the expedition which discovered and collected the holotype (original specimen). Zupaysaurus was first described and named in the scientific journal Ameghiniana by Argentine paleontologists Andrea Arcucci and Rodolfo Coria in 2003.[1]
Originally, Zupaysaurus was classified as the earliest known tetanuran theropod due to several features of its skull and hindlimb. However, several features typical of more basal theropods were also noted by the original authors.[1] More recent analyses, both published and unpublished, have agreed with the latter assessment, establishing Zupaysaurus as a coelophysoid related to Segisaurus and Dilophosaurus, probably more basal than the group containing Liliensternus, Megapnosaurus (Syntarsus), and Coelophysis.[3][4] Yates (2006) found Zupaysaurus to form a group with Dilophosaurus and Dracovenator, placing it in a monophyletic Dilophosauridae.[5]. But later studies [6],[7] found "Zupaysaurus" to be not a dilophosaurid.
Provenance
Only one specimen of Zupaysaurus is known to science. Designated PULR-076, it includes a nearly complete skull, the right shoulder girdle, the lower right leg and ankle, and twelve vertebrae from the neck, back, and hips. Additional material of a smaller individual found at the same site may or may not belong to Zupaysaurus. Both specimens are housed in the collection of the National University of La Rioja in La Rioja, Argentina.[1]
Zupaysaurus is known from the "Quebrada de los Jachaleros" locality within the Los Colorados Formation of La Rioja province in Argentina. This formation is usually thought to date to the Norian stage of the Late Triassic Period (216 to 203 Ma),[8] but has also been assigned to the slightly younger Rhaetian stage (203-200 Ma).[9] The Los Colorados Formation is also home to several types of early sauropodomorph dinosaurs (including Riojasaurus, Coloradisaurus, and Lessemsaurus).[8]
References
- ^ a b c d Arcucci, A.B. & Rodolfo A.C. 2003. A new Triassic carnivorous dinosaur from Argentina. Ameghiniana 40(2):217-228.
- ^ Currie, P.J. & Zhao X. 1993. A new carnosaur (Dinosauria, Theropoda) from the Jurassic of Xinjiang, Peoples' Republic of China. Canadian Journal of Earth Sciences 30: 2037-2081.
- ^ a b Ezcurra, M.D. & Novas, F.E. 2005. Phylogenetic relationships of the Triassic theropod *Zupaysaurus rougieri* from NW Argentina. Presented in August 2005 during the II Latin American Congress of Vertebrate Paleontology in Rio de Janeiro, Brazil. This analysis will be published in peer-reviewed print form later in 2006. A summary of the talk can be seen here.
- ^ Carrano, M.T., Hutchinson, J.R., & Sampson, S.D. 2005. New information on Segisaurus halli, a small theropod dinosaur from the Early Jurassic of Arizona. Journal of Vertebrate Paleontology 25(4): 835-849.
- ^ Yates, A.M., 2006 (for 2005). "A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods." Palaeontologia Africana, 41: 105-122.
- ^ Smith N.D., Makovicky P. J., Hammer W. R. & Currie P. J. 2007 Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution. Zool. J. Linn. Soc. 151, 377–421.
- ^ Nesbitt, S. J., Smith, N. D., Irmis, R. B., Turner, A. H., Downs, A., & M. A. Norell. 2009. A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs. Science 326:1530-1533.
- ^ a b Weishampel, D.B., Barrett, P.M., Coria, R.A., Le Loueff, J., Xu X., Zhao X., Sahni, A., Gomani, E.M.P., & Noto, C.R. 2004. Dinosaur distribution. In: Weishampel, D.B., Dodson, P., & Osmólska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 517-606.
- ^ Heckert, A.B. & Lucas, S.G. 1998. Global correlation of the Triassic theropod record. Gaia 15: 63-74. [not printed until 2000]
External links
- Zupaysaurus entry in The Theropod Database.
