Gualicho

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. 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. ==Description==

Like the well-known Tyrannosaurus, to which it has been compared, the 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. 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. ==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: 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. In their comprehensive revision of Santanaraptor and Mirischia, Delcourt et al. (2025) recovered Deltadromeus and Gualicho as sister taxa within Ornithomimosauria based on both equal and implied weight phylogenetic analyses. ==See also==