| Gualicho | |
|---|---|
 | |
| Speculative skeletal reconstruction, with known elements in white | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Neotheropoda |
| Clade: | Averostra |
| Genus: | †Gualicho Apesteguía et al., 2016 |
| Type species | |
| †Gualicho shinyae Apesteguía et al., 2016 | |
| Synonyms | |
| |
Gualicho (named in reference to thegualichu) is an enigmaticgenus oftheropod dinosaurs. Thetype species isGualicho shinyae. It lived in what is now northernPatagonia, on what was then a South American island continent split off from thesupercontinentGondwana. The fossils were found in theHuincul Formation, dating to the lateCenomanian-earlyTuronian age of the upperCretaceousPeriod, around 91million years ago.
On 13 February 2007, Akiko Shinya, preparator of theField Museum of Natural History, east of theEzequiel 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 thegualichu, a demon of local folklore. Thespecific name honours Shinya as the animal's discoverer.[1]
Theholotype, 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 bothmetatarsi 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 besynonymous with the megaraptoranAoniraptor, also known from Huincul Formation and uncovered at the Violante site in view of similarities in their caudal vertebrae. If this were supported, the nameGualicho would have precedent.[2][3] Aranciaga Rolando et al. in 2020 performed a comparative analysis between the pneumatic structures ofAoniraptor andGualicho, and found many differences between the two.[4]
Like the well-knownTyrannosaurus, 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]
Gualicho has been interpreted as presenting two evolutionary scenarios: that megaraptorans and neovenatorids wereallosauroids, or that megaraptorans and neovenatorids were a grade of theropods more closely related tocoelurosaurs than to carnosaurs. The cladogram below follows a 2016 analysis by Apesteguía et al., withGualicho withinCarcharodontosauria:[1]
Thecladogram below follows the strict consensus (average result) of the twelve mostparsimonious trees (the simplest evolutionary paths, in terms of the total amount of sampled features evolved or lost between sampledtaxa) found by Porfiri et al. (2018)'s phylogenetic analysis.[7] Although the results are different, withGualicho within Coelurosauria, the methodology analysis was practically identical to that of Apesteguia et al. (2016), only differing in the fact that it incorporatedTratayenia andMurusraptor, two megaraptorans not sampled in the analysis of Apesteguia et al.[1]
In 2025, Calvo and colleagues compared the humerus ofGualicho to that of other megaraptorans including a specimen of adultMegaraptor, 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] In their comprehensive revision ofSantanaraptor andMirischia, Delcourt et al. (2025) recoveredDeltadromeus andGualicho as sister taxa withinOrnithomimosauria based on both equal and implied weight phylogenetic analyses.[9]
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