With you, Meraxes gigas: Argentine Tyrannosaurus Rex

The Tyrannosaurus Rex He was one of the scariest dinosaurs ever to roam the planet, but he’s also the laughing stock of the dinosaur kingdom because of his diminutive arms. do not worry, R rexArgentinian researchers They found you a friend who shares your silly little guns.

Miraxis Gegas It is a carnivorous dinosaur whose bones have been discovered and studied by scientists in Argentina during the past decade. His research began in 2012, when fossils of an unknown species appeared in A Exploration in Argentina. They classified the specimen into a group of theropods known as Carcharosontosauridae, but upon closer examination, they didn’t know which species it might be. This uncertainty eventually led them to classify the animal as something new. They called it “Giga” because of its enormous size (about 11 meters tall and about 4 tons) and “Meraxes” in honor of a dragon from the fantasy series Ice and Fire Song by George RR Martin.

The creature’s small arms are sure to draw attentionbut the reason for the small size of these dinosaurs remains a mystery.

“It’s very, very difficult to figure out what those little arms do. We need a time machine,” Juan Ignacio Canal said in a video call with Gizmodo. Canal is a paleontologist at National Council for Scientific and Technical Research of Buenos Aires and lead author of the new study Posted today in current biology. Study authors They agree that these short arms have some kind of function. It is unlikely that those weapons will be useless“.

Researchers believe the arms had a function because M Gigas He had a very large shoulder, indicating that he once had strong arm muscles. Small arms would have helped the dinosaur to rise from a prone position, allowing it to do so Cling to a mate during breeding or prevent dinosaurs from mutilating each other when a group feeds on a carcass. Surprisingly, however, is that these small arms are found in groups of unrelated predators.

Canale y sus colegas compararon la presencia de diminutos brazos entre tres grupos de dinosaurios (los tiranosáuridos, los abelisáuridos y los carcarodontosáuridos) y descubrieron que cada uno de ellos desarrolló extremidades anteriores cortas de forma independiente.

“Lo que es notable es que estos dinosaurios de brazos cortos son parientes lejanos en el árbol genealógico de los dinosaurios. Esto significa que los brazos diminutos evolucionaron varias veces en diferentes grupos de dinosaurios carnívoros gigantes”, dijo Akinobu Watanabe, un paleontólogo no afiliado a esta investigación, por correo electrónico. Watanabe es profesor asociado de anatomía en el Instituto de Tecnología de Nueva York e investigador asociado en la División de Paleontología del Museo Americano de Historia Natural.

Watanabe sospecha que el pequeño tamaño de los brazos de M. gigas podría ser el resultado de una evolución que favorece una cabeza grande y una mandíbula poderosa, características que eran herramientas potencialmente más efectivas para la caza.

Steve Brusatte, paleontólogo de la Universidad de Edimburgo, se hizo eco de la teoría de Watanabe. “Los brazos diminutos eran algo normal para los [carnívoros] Huge,” Brusatte told Gizmodo in an email. “The reason remains unclear, but I suspect it is because the heads of these beasts have become so large and powerful that they have taken care of almost everything when it comes to eating: grabbing prey, killing it, chopping it up and devouring it. . brusatte is not New research continued, but it was a review of the article.

Kanal and colleagues found M Gigas in deposit about 10 kilometers From El Chocón, Argentina, a region in northern Patagonia that is usually very cold and dry with little vegetation, but M Gigas became extinct at the beginning of the late Cretaceous period, 90 million to 95 million years ago. At that time, the world looked completely different. This part of the land was warm, humid, and fertile, and the area shared biodiversity with Africa, Kanall says: “South America was very close to or even in contact with Africa. The Atlantic Ocean began to form.”

The initial excavation took place in 2012, after Kanal and a colleague found a small piece of sauropod five years earlier during an exploratory visit to the site.with more fossils located under about 2 metres of sandstone three hard hikes After a month-long field trip and a few hammer strikes later, the researchers were able to extract the fossils and begin processing them. But Kanal says the study of this new sample has only just begun. “We have a lot to work on. We have to do the detailed descriptions, and we have to do a CT scan of the skull to see the interior spaces. So there is still a lot to do.”