Meraxes – named after a fictional dragon from the Game of Thrones book series – was excavated over four years during field expeditions in Argentina’s northern Patagonia, starting with the skull discovered in 2012.
Paleontologists said Thursday they discovered a new giant carnivorous dinosaur species that had a massive head and small arms, just like Tyrannosaurus rex.
The researchers’ findings, published in the journal Current Biologysuggest that the small forelimbs were not an evolutionary fluke, but rather gave the apex predators of the time certain survival advantages.
Meraxes gigas – named after a fictional dragon from the Game of Thrones book series – was excavated over four years during field expeditions in northern Argentina’s Patagonia, starting with the skull discovered in 2012.
“We won the lottery and found it literally on the first morning,” senior author Peter Makowicki of the University of Minnesota told AFP.
The fossilized remains are remarkably well preserved. The skull is just over four feet (127 centimeters) long, while the entire animal would have been about 36 feet long and weighed four metric tons.
Its arms were two feet long, “so it’s literally half the length of the skull, and the animal wouldn’t have been able to reach its mouth,” Makowicki said.
T. rex did not get its small arms from M. gigas. The latter became extinct 20 million years before the former appeared, and the two species were far apart in the evolutionary tree.
This image shows the transport of a plaster jacket of a new Meraxes gigas dinosaur, in Las Campanas Canyon, 25 km southwest of Villa El Chocón, Neuquen Province, Argentina, on March 17, 2014.
Instead, the authors believe that the fact that tyrannosaurids, carcharodontosaurids—the group to which the Meraxes belong—and a third giant carnivore species called abelisaurids evolved small arms indicates certain advantages.
Makovicky believes that as their heads became larger, it became the dominant tool in their predatory arsenal, taking over the function that the forelimbs would have had in smaller species.
His co-author Juan Canale, the project manager at the Ernesto Bachmann Paleontological Museum in Neuquen, Argentina, went further in suggesting other advantages.
Mating and assisting locomotion
“I’m convinced that those proportionally small hands had some function. The skeleton shows large muscle insertions and fully developed pectoral girdle, so the arm had strong muscles,” he said in a statement.
“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.”
This image shows the excavation site of a new dinosaur, Meraxes gigas, in Las Campanas Canyon, 25 km southwest of Villa El Chocón, Neuquen Province, Argentina, on March 15, 2014.
Meraxes roamed the Earth between 90 and 100 million years ago during the Cretaceous, at a time when the region was wetter, more forested and much closer to the sea, Makowicki said.
They would prey on a menagerie of modern sauropods – some of which have been found at the same site.
The individual lived to be about 40 years old – a ripe age for dinosaurs – and its skull is full of crests, furrows, ridges and small horns.
“It would certainly look very imposing and gargoyle-like,” Makowitzki said.
“These are the kinds of traits that, in living animals, are often subject to sexual selection,” speculating that the species used their massive skulls as “billboards” to advertise prospective mates.
New giant carnivorous dinosaur with tiny arms like T. rex discovered 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
© 2022 AFP
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