La T-Rex: Discover a huge dinosaur with tiny arms

In Patagonia, paleontologists discovered the bones of a predatory dinosaur, with its large skull and short arms, reminiscent of the famous T. rex sore. Despite the external similarity, dinosaurs are not related to each other, The researchers wrote in the journal Current Biology. Meraxes gigas, as the new carnivore is called, and T. rex developed their disproportionately short arms independently. It is still not clear why they used it.

During excavations in the so-called Huincul Formation in what is now northern Patagonia, researchers found skull fragments and a large number of bones. According to the researchers, it is the most complete fossil remains of the representative Carcharodontosauridae found in the Southern Hemisphere. Carcharodontosauridae It indicates a large group theropodsthat lived in the Cretaceous period and included giant predatory dinosaurs.

The eleven-meter-tall robber was approximately 45 years old

Meraxes gigas was just a giant predator: the researchers reported that the 45-year-old specimen they discovered was 11 meters long when alive and weighed more than four tons. Its skull, about 1.27 meters long, is decorated with crests, grooves, spurs and small squirrels.

“These traits appeared late in evolution, when the animals became adults,” explains lead author Juan Canal of the Ernesto Bachmann Paleontological Museum in Neuquén, Argentina. They supposedly served to attract potential mates: “Sexual selection is a powerful evolutionary force. But since we cannot directly observe their behavior, it is impossible to be certain.”

However, researchers are sure that Meraxes gigas did not get their remarkably short arms from Tyrannosaurus Rex or vice versa: on the one hand, M. gigas died nearly 20 million years before the appearance of T. rex. On the other hand, the two species are very far apart in the evolutionary tree. Kanal explains that “there is no direct relationship between the two.”

The short arms had a job – but which one?

However, if such short arms were developed independently in different species of theropod, one must assume that the shortened limbs had a specific function – and they did not shrink simply because they were useless to dinosaurs. In addition, the skeleton showed large muscular attachments and fully developed pectoral corsets. “So the arm was strong,” explains project manager Juan Canal.

However, this muscle strength may not have been used for hunting, because “the actions associated with hunting prey were most likely done with the head.” Kanal speculates: “They could have used their arms for breeding, for example to hold the female during mating.” It is also conceivable that the limbs were useful in getting up again after a fall. (dpa/ft)