Biology:Gualicho
Gualicho (named in reference to the gualichu) is an enigmatic genus of theropod dinosaurs. The type species is Gualicho shinyae. It lived in what is now northern Patagonia, on what was then a South American island continent split off from the supercontinent Gondwana. The fossils were found in the Huincul Formation, dating to the late Cenomanian-early Turonian age of the upper Cretaceous Period, around 91 million years ago.
Discovery
On 13 February 2007, Akiko Shinya, preparator of the Field Museum of Natural History, east of the Ezequiel Ramos Mexía Reservoir at the Rancho Violante, discovered the skeleton of a theropod new to science. In 2016, the specimen was named and described by Sebastián Apesteguía, Nathan D. Smith, Rubén Juárez Valieri and Peter J. Makovicky. The generic name is derived from the gualichu, a demon of local folklore. The specific name honours Shinya as the animal's discoverer.[1]
The holotype, MPCN PV 0001, consists of a partial skeleton lacking the skull. It contains four vertebrae of the back, three vertebrae of the middle tail, ribs, a basket of belly-ribs, the left shoulder girdle, the left forelimb, the right lower arm, the lower ends of both pubic bones, the right thighbone, the lower end of the left thighbone, the upper ends of the right shinbone and calf bone, elements of both metatarsi and three toes of the right foot. Most bones were uncovered in their original anatomical position but much of the skeleton had been destroyed by erosion.[1]
Gualicho has been informally suggested on blogs to be synonymous with the megaraptoran Aoniraptor, also known from Huincul Formation and uncovered at the Violante site in view of similarities in their caudal vertebrae. If this were supported, the name Gualicho would have precedent.[2][3] Aranciaga Rolando et al. in 2020 performed a comparative analysis between the pneumatic structures of Aoniraptor and Gualicho, and found many differences between the two.[4]
Description
Like the well-known Tyrannosaurus, to which it has been compared, the 6–7 m (20–23 ft) Gualicho possesses reduced arms and possibly two fingered hands, although a 2020 study suggests enough of the third metacarpal is present for a third finger.[5] If it is an allosauroid, this finding indicates that carnosaurs may have been subject to the same evolution of limb-reduction as tyrannosaurids and abelisaurids.[6]
Classification
Gualicho has been interpreted as presenting two evolutionary scenarios: that megaraptorans and neovenatorids were allosauroids, or that megaraptorans and neovenatorids were a grade of theropods more closely related to coelurosaurs than to carnosaurs. The cladogram below follows a 2016 analysis by Apesteguía et al., with Gualicho within Carcharodontosauria:[1]
| Allosauroidea |
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The cladogram below follows the strict consensus (average result) of the twelve most parsimonious trees (the simplest evolutionary paths, in terms of the total amount of sampled features evolved or lost between sampled taxa) found by Porfiri et al. (2018)'s phylogenetic analysis.[7] Although the results are different, with Gualicho within Coelurosauria, the methodology analysis was practically identical to that of Apesteguia et al. (2016), only differing in the fact that it incorporated Tratayenia and Murusraptor, two megaraptorans not sampled in the analysis of Apesteguia et al.[1]
| Avetheropoda |
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In 2025, Calvo and colleagues compared the humerus of Gualicho to that of other megaraptorans including a specimen of adult Megaraptor, and concluded that this taxon is not closely related to them due to significant morphological differences. They also noted that the features of its humerus shares many similarities to various groups of coelurosaurs, so a confident referral within a specific clade of theropods cannot be made.[8]
See also
- 2016 in paleontology
References
- ↑ 1.0 1.1 1.2 1.3 "An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina". PLOS ONE 11 (7). 2016. doi:10.1371/journal.pone.0157793. PMID 27410683. Bibcode: 2016PLoSO..1157793A.
- ↑ Mortimer, Mickey (2016-07-13). "Is Gualicho Aoniraptor?". http://theropoddatabase.blogspot.com/2016/07/is-gualicho-aoniraptor.html.
- ↑ Cau, Andrea. "Nuovi resti di Aoniraptor? Ehm... Benvenuto Gualicho!". http://theropoda.blogspot.com/2016/07/nuovi-resti-di-aoniraptor-ehm-benvenuto.html.
- ↑ Rolando, Mauro Aranciaga; Marsà, Jordi Garcia; Novas, Fernando (2020). "Histology and pneumaticity of Aoniraptor libertatem (Dinosauria, Theropoda), an enigmatic mid-sized megaraptoran from Patagonia" (in en). Journal of Anatomy 237 (4): 741–756. doi:10.1111/joa.13225. ISSN 1469-7580. PMID 32470191.
- ↑ Ibrahim, Nizar; Sereno, Paul C.; Varricchio, David J.; Martill, David M.; Dutheil, Didier B.; Unwin, David M.; Baidder, Lahssen; Larsson, Hans C. E. et al. (2020-04-21). "Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco" (in en). ZooKeys (928): 1–216. doi:10.3897/zookeys.928.47517. ISSN 1313-2970. PMID 32362741. PMC 7188693. Bibcode: 2020ZooK..928....1I. https://zookeys.pensoft.net/article/47517/.
- ↑ Davis, Nicola (13 July 2016). "Meet Gualico shinyae, the puny armed distant relative of T-rex". The Guardian. https://www.theguardian.com/science/2016/jul/13/meet-gualicho-shinyae-the-puny-armed-distant-relative-of-t-rex.
- ↑ Porfiri, Juan D.; Juárez Valieri, Rubén D.; Santos, Domenica D.D.; Lamanna, Matthew C. (March 2018). "A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia". Cretaceous Research 89: 302–319. doi:10.1016/j.cretres.2018.03.014. Bibcode: 2018CrRes..89..302P.
- ↑ Calvo, J. O.; Porfiri, J. D.; Aranciaga Rolando, A. M.; Novas, F. E.; Dos Santos, D. D.; Wessel, D. E.; Lamanna, M. C. (2025). "Morphological and Phylogenetic Significance of the First Adult Humerus of the Patagonian Cretaceous Theropod Megaraptor namunhuaiquii Novas, 1998". Annals of Carnegie Museum 90 (3): 161–181. doi:10.2992/007.090.0301.
Template:Theropoda Wikidata ☰ Q25859335 entry
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