What Has Little Arms with Two Fingers?

What Has Little Arms with Two Fingers?
Figure 1 of the paper.

If you were thinking Tyrannosaurus rex, you would be right. But today we are talking about a brand new dinosaur, not related to T. rex that also has little arms with two fingers! This new dinosaur was discovered in the Neuquén Basin of Argentina and it’s from the Late Cretaceous (about 90 million years ago).

Map of Neuquén, Argentina.

Map of the Neuquén Basin, Argentina.

It was named Gualicho shinyae. The name Gualicho comes from a Spanish word for an animal-owning goddess in the Gennaken language (an extinct language spoken by the Puelche people of the Pampas, Argentina). The name shinyae is in honor of Akiko Shinyo, a preparator at the Field Museum of Natural History in Chicago, for her many contributions to paleontology and because she discovered the fossil in 2007.


The skeleton of Gualicho. White bones are the bones they found. Gray bones are a representation of what the rest would look like.

The authors of the [study] analyzed the characteristics of the bones and found that Gualicho represents a new lineage of theropod dinosaurs. Its closest relative turned out to be Deltadromeus, a theropod from around the same time in Western Africa.

This find is really exciting because it shows features from ceratosaurs, tyrannosaurs, and megaraptorans – a combination that we had not seen in a theropod before. It also shows how Africa and South America used to be connected in the Mesozoic: since Gualicho (from South America) and Deltadromeus (from Africa) are closest relatives, their ancestors had to be present in one area, the expansion of the Atlantic Ocean caused Africa and South America to move apart, leading to the evolution of these two species.

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