Big head and small arms: Discovery of a new dinosaur in Argentina

Paleontologists announced on Thursday that they had discovered the remains of a new giant dinosaur in Argentina.

Remarkable for its huge head and small arms, the specimen was named

, after a dragon from the

series .

The carnivorous predator was discovered during excavations carried out over four years in northern Patagonia, specifies the study published in the journal

.

The skull was found first, in 2012. “We won the lottery, we discovered it the first morning,” recalls American researcher Peter Makovicky.

New giant #dinosaur from the Cretaceous of Argentina: Meraxes gigas.

It provides key data to analyze the convergent evolution of small forelimbs across theropod clades.

Also among the oldest (ontogenetically) known theropod: ~40-50 yrs old!

Paper: https://t.co/XcoUMzTmT8 pic.twitter.com/mn4RgIkhfb

— Thomas Cullen (@cullen_thomas) July 7, 2022

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A big head and small muscular arms

The skull measured more than 1.20 m and the animal more than 10 m, for a weight of about four tons.

But its upper limbs were no longer than 60 cm, "half the skull" and the animal could not use them to "reach its mouth", specifies the researcher.

Scientists believe that the small size of the arms gave the animal a certain advantage in surviving.

Indeed, as it grew, the head gradually became the dominant tool in the dinosaur's predatory arsenal, assuming the function that the upper limbs had in smaller species.

“These proportionally reduced arms had a function”, assures Juan Canale, co-author of the study.

“The skeleton shows large muscle insertions and fully developed chest girdles, so the arms had strong muscles.

»

Sexual selection by head size

The

lived on Earth 90 to 100 million years ago, during the Cretaceous when the region was wetter, more wooded and closer to the sea. These dinosaurs could live for up to 40 years, a advanced age.

They presumably hunted sauropods living at the same time, the remains of which have been discovered at the excavation site.

With its skull riddled with ridges, grooves, bumps and small horns,

"looked like a gargoyle" and "looked imposing" according to the researchers.

In animals, these characteristics “are often the subject of sexual selection”, emphasizes Peter Makovicky.

According to him, these species surely used their massive skull as a "billboard" to get noticed by partners.

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