in Argentina, a predatory dinosaur reveals some secrets

Three years after its discovery in southern Argentina, the fossil of a dinosaur gradually reveals its secrets: 70 million years old, measured 10 meters long, it was a large predator that removed its prey using sharp, curved claws.

The remains of this “megaraptor”, a carnivorous dinosaur with large hind legs and small upper limbs, were discovered in March 2019 in the southern part of the province of Santa Cruz in Patagonia, 30 km south of the tourist town of El Calafate.

Mauro Aranciaga, a 29-year-old paleontologist working at the Comparative Anatomy Laboratory at the Museum of Natural Sciences in Argentina, directed by Fernando Novas, discovered the first piece of the skeleton while participating in his first excavation campaign in 2019.

“When I lifted the vertebra, I saw that it had the characteristics of a megaraptor. It was really a huge feeling, I saw a giant vertebra, and that meant we were dealing with a giant megaraptor,” the young researcher recalls.

“I realized a childhood and adult dream!” he told AFP at the laboratory premises in Buenos Aires.

Three years later, after tedious work on extraction, transportation, cleaning and long months of laboratory research, the first conclusions regarding “Maip macrothorax”, its name, have just been published in the scientific journal Nature.

“It was a large animal, according to the measurements and comparisons we made (…) It is also one of the last megaraptors to inhabit the planet before the extinction of dinosaurs about 66 million years ago,” explains Fernando Novas, the director of the laboratory.

– tear the prey –

This Argentine paleontologist has a long history of discovery behind him.

In 1996, he found the remains of the very first representative of the megaraptor group 1,400 km away, in the province of Neuquen (south).

Others were then discovered in Australia, Thailand, Japan, he says.

Far from the titanosaurs, the largest known dinosaurs, which can measure about thirty meters and weigh 70 tons, the megaraptors listed so far have been between 8 and 9 meters long.

“This one measured between 9 and 10 meters long and weighed about 6 tons”, the largest of the hitherto known megaraptors, explains Mauro Aranciaga, who also points out that he was “at the top of the food chain” in its ecosystem.

Several vertebrae, ribs, hip, tail and arm pieces were found.

The researchers were also “surprised to find that megaraptors had huge claws on their thumb and forefinger.

They had three fingers on their hands, but their claws were about forty centimeters long, ”says Novas.

“Of course, these claws had to be used to catch prey, tear them apart and rummage inside them,” he adds.

Hence its christening name: “Maip” is a Tehuelche word, a native people of southern Argentina, which refers to an evil spirit or “the shadow that death leaves behind after its passage”.

As for his thorax, it measured up to 1.20 meters wide, 1.50 meters long, according to the researchers.

“Maip had such a large thorax that the insertions of the ligaments that connect the vertebrae with the ribs were preserved. It allows us to go a little further and reconstruct parts that are not normally preserved,” explains Mauro Aranciaga.

Fernando Novas says that the discovery took place in an “extraordinary occurrence, which turns out to be one of the most important in South America”. It dates from the Cretaceous (-145 to -66 million years) “where there were neither the Andes nor the glaciers, but rather tropical forests, in which a great diversity of animals lived”.

The first traces of the presence of a fossil deposit in the area appeared in 1980 thanks to the work of Argentine geologist Francisco Nulo, but the first real campaign was launched in 2019 by Fernando Novas’ team.

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