Dinosaur discovered in Argentina was armless but fierce

A new species of dinosaur, named Guemesia ochoai, has recently been discovered in the Los Blanquitos Formation near Amblayo, in the north of Argentina. It is a species of abelisaurid theropods, a clade of carnivorous dinosaurs that lived 70 million years ago and roamed what is now South America, Africa, and India. As most abelisaurids, this dinosaur had very short front limbs, a feature which probably made it rely on its extremely powerful head and jaws to capture and devour prey.

Abelisaurids were a group of top predatory dinosaurs that may have fed on larger dinosaurs such as titanosaurs. While they resembled in general appearance more famous species such as Tyrannosaurus rex, they had even shorter front limbs than T. rex, as well as unusually short, deep skulls that often bore crests, bumps, and horns.

Argentina is well known for its abelisaurid fossils, with 35 species already discovered on its territory. However, most of the fossils have been found in Patagonia, in the south of the country. Guemesia ochoai – named after General Martin Miguel de Güemes, a hero of the Argentine War of Independence, and Javier Ochoa, a museum technician who discovered the fossils – shows marked differences from other species of abelisaurids discovered in Argentina, adding new evidence that north-western Argentina had a unique set of prehistoric creatures, unlike those found in other parts of the world in the Late Cretaceous.

“This new dinosaur is quite unusual for its kind. It has several key characteristics that suggest that is a new species, providing important new information about an area of the world which we don’t know a lot about,” said study senior author Anjali Goswami, a researcher at the Natural History Museum in London. 

“It shows that the dinosaurs that live in this region were quite different from those in other parts of Argentina, supporting the idea of distinct provinces in the Cretaceous of South America. It also shows us that there is lot more to be discovered in these areas that get less attention than some of the more famous fossil sites.”

One unique feature of this specimen are the rows of small holes in the front of its skull called “foramina,” which scientists believe that may have played an important role in allowing the animal to cool down, with blood being pumped into the thin skin from the front of the skull to release heat. Moreover, its cranium is about 70 percent smaller than any of its relatives, and, unlike most other abelisaurid skulls, it lacks horns. These differences suggest that this new species is near the bottom of the family tree of abelisaurids or closely related to ancestors of this group.

A detailed description of G.ochoai is published in the Journal of Vertebrate Paleontology. 

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By Andrei Ionescu, Earth.com Staff Writer