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An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina.
PLoS One. 2016; 11(7):e0157793.Plos

Abstract

BACKGROUND

Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit.

METHODOLOGY/ PRINCIPAL FINDINGS

A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton.

CONCLUSIONS/ SIGNIFICANCE

Gualicho shinyae gen. et sp. nov. increases the known theropod diversity of the Huincul Formation and also represents the first likely neovenatorid from this unit. It is the most basal tetatanuran to exhibit common patterns of digit III reduction that evolved independently in a number of other tetanuran lineages. A close relationship with Deltadromaeus from the Kem Kem beds of Niger adds to the already considerable biogeographic similarity between the Huincul Formation and coeval rock units in North Africa.

Authors+Show Affiliations

Área de Paleontología. Fundación de Historia Natural 'Félix de Azara', CEBBAD, Univ. Maimónides, Buenos Aires, Argentina.Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, United States of America.Secretaría de Cultura, Gobierno de la Provincia de Río Negro, General Roca, Argentina.Section of Earth Sciences, Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, United States of America.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

27410683

Citation

Apesteguía, Sebastián, et al. "An Unusual New Theropod With a Didactyl Manus From the Upper Cretaceous of Patagonia, Argentina." PloS One, vol. 11, no. 7, 2016, pp. e0157793.
Apesteguía S, Smith ND, Juárez Valieri R, et al. An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. PLoS One. 2016;11(7):e0157793.
Apesteguía, S., Smith, N. D., Juárez Valieri, R., & Makovicky, P. J. (2016). An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. PloS One, 11(7), e0157793. https://doi.org/10.1371/journal.pone.0157793
Apesteguía S, et al. An Unusual New Theropod With a Didactyl Manus From the Upper Cretaceous of Patagonia, Argentina. PLoS One. 2016;11(7):e0157793. PubMed PMID: 27410683.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. AU - Apesteguía,Sebastián, AU - Smith,Nathan D, AU - Juárez Valieri,Rubén, AU - Makovicky,Peter J, Y1 - 2016/07/13/ PY - 2015/12/11/received PY - 2016/06/02/accepted PY - 2016/7/14/entrez PY - 2016/7/15/pubmed PY - 2017/7/25/medline SP - e0157793 EP - e0157793 JF - PloS one JO - PLoS One VL - 11 IS - 7 N2 - BACKGROUND: Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit. METHODOLOGY/ PRINCIPAL FINDINGS: A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton. CONCLUSIONS/ SIGNIFICANCE: Gualicho shinyae gen. et sp. nov. increases the known theropod diversity of the Huincul Formation and also represents the first likely neovenatorid from this unit. It is the most basal tetatanuran to exhibit common patterns of digit III reduction that evolved independently in a number of other tetanuran lineages. A close relationship with Deltadromaeus from the Kem Kem beds of Niger adds to the already considerable biogeographic similarity between the Huincul Formation and coeval rock units in North Africa. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/27410683/An_Unusual_New_Theropod_with_a_Didactyl_Manus_from_the_Upper_Cretaceous_of_Patagonia_Argentina_ DB - PRIME DP - Unbound Medicine ER -