meraxes gigasa newly discovered dinosaur species with disproportionately short arms T. rex. Credit: Jorge A Gonzalez
meraxes gigas – discovered a new species of dinosaur with disproportionately short arms T. rex called meraxes gigas.
Tyrannosaurs (infamous T. rex) are not the only group of huge carnivorous dinosaurs with tiny arms. In fact, paleontologists have discovered a new species of dinosaur with disproportionately short arms just like it. T. rex called meraxes gigas. Findings published in the journal Current Biology today (July 7), argued T. rex and m. giga developed completely independently to have small arms, and identified various potential functions for short arms, such as mating or locomotion support.
“Fossil m. giga It shows never-before-seen, complete skeletal regions such as arms and legs that help us understand some evolutionary trends and the anatomy of Carcharodontosaurids. m. giga belongs to him,” says Juan Canale, project leader at the Ernesto Bachmann Museum of Paleontology in Neuquén, Argentina.
First, to fix the record, the authors say: T. rex they couldn’t get their short sleeves m. giga or vice versa. I just didn’t m. giga extinct almost 20 million years ago T. rex became one species, but they are also very far apart on the evolutionary tree. “There’s no direct relationship between the two,” Canale says. On the contrary, Canale believes that having small arms somehow gave the two dinosaurs a kind of survival advantage.
meraxes gigas It is a giant carnivorous dinosaur. Credit: Carlos Papolio
“I’m convinced that proportionally small arms have some kind of function. Canale says the arm has strong muscles because the skeleton has large muscle placements and fully developed thoracic girdles. This suggests that the arms didn’t get smaller because they didn’t work for the dinosaurs. The harder question is the exact function of the functions.” as what it is.
From past studies, the research group, for dinosaurs m. giga and T. rexAs their heads got bigger, their arms got smaller. They were certainly not useful for hunting, as “actions related to hunting were most likely performed by the head,” Canale said.
“I tend to think that their weapons were used in other types of activities,” Canale says. The team was able to draw a picture of this creature’s life from the fossil record. m. giga before death. The dinosaur, which lived in present-day northern Patagonia of Argentina, was 45 years old, about 11 meters long and weighed more than four tons. And he had a big family. “The group evolved shortly before extinction and reached the peak of diversity,” Canale says. “They may have used the arms for reproductive behavior, such as holding the female during mating or supporting themselves to stand up after a break or fall,” adds Canale.
excavation site meraxes gigas. Credit: Juan I Canale
The team also m. giga It is decorated with hills, grooves, mounds and small horns. “These ornaments appear late in development when individuals become adults,” Canale says. The group thinks the features are likely 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 excellent condition,” Canale says. He looks forward to exploring other questions to ask. m. giga The fossil may help him answer. “We found the perfect place on the first day of searching and m. giga “It was probably one of the most exciting points of my career,” Canale says.
Reference: Juan I. Canale, Sebastián Apesteguía, Pablo A. Gallina, Jonathan Mitchell, Nathan D. Smith, Thomas M. Cullen, Akiko Shinya, Alejandro Haluza, Federico, “The new giant carnivorous dinosaur reveals convergent evolutionary trends in the reduction of the theropod clade. putting it in” A. Gianechini, Peter J. Makovicky, 7 July 2022, Current Biology.
DOI: 10.1016/j.cub.2022.05.057
This work was supported by the United States National Science Foundation and the National Geographic Society.
