L'Abélisauridé Carnotaurus sastrei

Discovery of a new species of dinosaur belonging to an “armless” family in Argentina

In Argentina, a new species of dinosaur called Guemesia ochoai was recently discovered. The species was identified from a single skull approximately 70 million years old, and found in northwestern Argentina. According to scientists, G. ochoai believed to belong to a clade of carnivorous dinosaurs called Abelisaurids which are primarily known for their tiny arms.

Abelisaurids were once present in Europe, Africa, India and South America. However, they disappeared about 66 million years ago. Compared to other species of the same family, the skull of G. ochoai was particularly small. Its size would be equivalent to only 70% of that of the famous genus Carnotaurus who lived in the far south of South America.

Guemesia ochoai is thus among the abelisaurids known to date and having the smallest brain.

A sizeable predator

According to the researchers, the newly discovered species had sagging arms across its broad chest. Like all species of the Abelisaurid family, G. ochoai was devoid of ossified wrists and movable joints at the elbows. She was thus unable to bend her upper appendages and grasp something between her fingers. Besides, she had no claws.

Even though abelisaurids could not use their arms to capture their prey, they evolved other abilities to compensate for this lack. Thanks to their strong jaws as well as their sharp teeth, they were able to bring down prey much larger than themselves.

New data on the distribution of abelisaurids

According to Anjali Goswami, NHM paleontologist in the UK, this new dinosaur species would be rather unusual for its genus. According to him, the discovery of G. ochoai supports the idea that during the Cretaceous there were distinct provinces in South America. Indeed, the dinosaurs that lived in the region where the new species was found look very different from those in other parts of Argentina.

On the other hand, recent findings have revealed that Abelisaurids have a much wider distribution in South America. They would have adapted to different isolated ecosystems after the division of Gondwana.

If until now all the abelisaurid fossils discovered in Argentina come from Patagonia, G. ochoai would be the first species of the family to have been discovered in the northwest. The species exhibits several characteristics that distinguish it from other abelisaurids, likely suggesting a life adapted to the hot climate. One can for example cite the presence of small holes on his skull which would have allowed G. ochoai release heat and cool down, including pumping blood to the surface of the skin.

For paleontologists, Argentina being still relatively unexplored, it is very likely that other species of Abelisaurids will be discovered there in the future.

SOURCE: sciencealert

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