The writers set the record straight first. T. rex did not get their short arms from M. gigas or vice versa. Not only did M. gigas go extinct nearly 20 million years before T. rex became a species, but they are also very far apart on the evolutionary tree. “There is no direct relationship between the two,” says Canale. Rather, Canale believes that having tiny hands somehow gave the two dinosaurs some sort of survival advantage.
title: “New Giant Carnivore Dinosaur Discovered With Tiny Arms Like T. Rex " ShowToc: true date: “2022-11-08” author: “Pamela Manion”
Tyrannosaurs (like the famous T. rex) aren’t the only group of giant carnivorous dinosaurs with tiny arms. Researchers have discovered a new species of dinosaur with disproportionately short T. rex-like arms called Meraxes gigas. The findings were published in the journal Current Biology on July 7, argued that T. rex and M. gigas evolved to have tiny arms independently and suggested some possible functions for the short arms, such as mating or supporting locomotion.
“The M. gigas fossil shows never-before-seen, complete regions of the skeleton, such as the arms and legs that have helped us understand some evolutionary trends and the anatomy of Carcharodontosaurids—the group to which M. gigas belongs,” says Juan Channel. , project leader at the Ernesto Bachmann Paleontological Museum in Neuquén, Argentina.
The writers set the record straight first. T. rex did not get their short arms from M. gigas or vice versa. Not only did M. gigas go extinct nearly 20 million years before T. rex became a species, but they are also very far apart on the evolutionary tree. “There is no direct relationship between the two,” says Canale. Rather, Canale believes that having tiny hands somehow gave the two dinosaurs some sort of survival advantage.
“I’m convinced that these proportionally tiny hands had some kind of function. The skeleton shows large muscle insertions and fully developed pectoral girdles, so the hand had powerful muscles,” says Canale. This means that the arms did not shrink because they were useless to the dinosaurs. The more difficult question is what exactly the functions were.
Meraxis. Credit: Carlos Papolio
From previous research, the team found that for dinosaurs like M. gigas and T. rex, the bigger their heads got, the smaller their hands got. They were certainly not useful for hunting, as “actions related to hunting were probably performed by the head,” Canale argues.
“I tend to think that their hands were used in other kinds of activities,” Canale says. From the fossil record, the team was able to paint a picture of the life of this M. gigas before it died. Living in what is now Argentina’s northern Patagonia region, the dinosaur was 45 years old, about 11 meters long and weighed more than four tons. And, he had a big family. “The team blossomed and reached the peak of diversity just before [they] disappeared,” says Canale. “They may have used the arms for reproductive behavior, such as holding the female during mating or supporting herself to get back up after a break or fall,” adds Canale.
Excavation site. Credit: Juan I Canale
The team also found that the skull of M. gigas was decorated with ridges, grooves, bumps and small hornlets. “These ornaments appear late in development, when individuals have reached adulthood,” says Canale. The team believes the traits were probably used to attract potential mates. “Sexual selection is a powerful evolutionary force. But since we can’t directly observe their behavior, it’s impossible to be sure,” says Canale.
“The fossil has a lot of new information and is in great shape,” says Canale. He looks forward to exploring other questions that the M. gigas fossil can help him answer. “We found the perfect spot on the first day of the search and M. gigas was found,” says Canale, “It was probably one of the most exciting spots of my career.”
T. rex’s short arms may have reduced bite risk during feeding frenzies More information: Juan I. Canale, New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction, Current Biology (2022). DOI: 10.1016/j.cub.2022.05.057. www.cell.com/current-biology/f … 0960-9822(22)00860-0
Reference: New giant carnivorous dinosaur discovered with tiny arms like T. rex (2022, July 7) retrieved July 7, 2022 by
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