Gualicho

Gualicho is a genus of theropod dinosaur from the early Late Cretaceous period (Cenomanian age) of Argentina. It is known from a single species, Gualicho shinyae.

Discovery and Naming

Gualicho shinyae was discovered in the Huincul Formation of Patagonia in Argentina. The genus name, Gualicho, refers to a mischievous, malevolent spirit or demon from the folklore of the Tehuelche people of Patagonia. The specific name, shinyae, honors Akiko Shinya for her work in supporting paleontological research.

Description

Gualicho was a relatively small theropod, estimated to have been about 6 meters (20 feet) long. It possessed a gracile build and long legs, suggesting it was a fast runner. While the holotype specimen is incomplete, certain features distinguish it from other theropods. Notably, the forelimbs were proportionally very short, with only two digits on the hand. This is a derived feature, distinguishing it from more basal tetanurans. The humerus was particularly short, and the ulna and radius were slender.

Classification

Phylogenetic analysis suggests that Gualicho belongs to a group of theropods called Megaraptora. Megaraptorans are a group of carnivorous dinosaurs known for their large claws on their hands and pneumatic bones. However, Gualicho exhibits a unique combination of features that place it as a relatively basal member of the Megaraptora clade, providing insights into the evolution of this group. Its position helps to understand the evolution of forelimb reduction within theropods and the biogeographic distribution of megaraptorans.

Paleoenvironment

Gualicho lived in a Late Cretaceous environment alongside other dinosaurs, including sauropods and other theropods. The Huincul Formation preserves a diverse assemblage of dinosaur fossils, providing valuable information about the ecosystems that existed in South America during this period.