Among the fossilized remains of Los Blanquitos formationin the remote Amblayo, a group of researchers has found the fossil of an extraordinary skull: it is the Guemesia ochoai, a new species of abelisaurid who lived approx 70 million years agowhen the supercontinent Gondwana began to crumble. This discovery, which occurred in the province of Salta, sheds new light on an area often overlooked by paleontologists, who for decades have mainly focused on the fossil riches of Patagonia.
The fossil, a almost complete skulltells a different story than its southern cousins. The Guemesia ochoai, a distinctive element of the abelisaurids, and its brain was surprisingly small: approximately 70% smaller than other members of the same family. But it is precisely this structural simplicity that makes it so unique.
The revolution of “belisaurids with little brain”
Abelisaurids, theropod dinosaurs known for their forelimbs practically uselessseem to be the natural response of prehistory to the concept of “do the most with what you have”. Despite tiny arms and a robust, decorated skull, these dinosaurs were fearsome predators, capable of taking down gigantic prey such as sauropods.
However, the Guemesia ochoai stands out for some details. There total absence of horns on the skull makes it a primitive species within its group, probably among the first to appear. Furthermore, gods were found in the skull foraminasmall holes through which the dinosaur may have dissipated heat to regulate its body temperature. An ingenious evolutionary trick for surviving in a torrid and hostile environment like that of the late Cretaceous.
According to the teacher Anjali Goswamiresearcher at the Natural History Museum in London, “this unusual dinosaur shows us how different the fauna of the Argentine north-west was compared to that of the rest of the country. A discovery that reinforces the idea of very distinct ecosystems during the South American Cretaceous.”
Argentina and the mystery of the northwestern dinosaurs
While the Patagonia has always represented the Mecca for paleontologists, thanks to its spectacular discoveries, the Argentine north-west has remained a sort of Cinderella of paleontology. With the Guemesia ochoai, this area begins to earn a place in the panorama of great finds.
The name of the new species is a tribute to both Martin Miguel de Güemeshero of Argentine independence, both a Javier Ochoathe museum technician who discovered the fossil.
This dinosaur, which lived at a time when Gondwana was separating into the southern continents we know today, makes us reflect on the evolution of abelisaurids in a particular ecological context. Geographic separation has likely created unique ecosystems, just waiting to be discovered. It is no coincidence that Professor Goswami declared:
To understand global events like mass extinction, we need to delve into the least explored areas of the planet. And here, in the Argentine north-west, there is still so much to discover.
A curiosity? Even if Argentina has already given the world 35 species of abelisauridsthis is the first significant discovery outside the borders of Patagonia. A small piece that adds depth to the complex evolutionary map of dinosaurs.
