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Argentine, a ferocious dinosaur with gargoyle-inspired ridges and a huge head covered at the top, offers insights into the evolution of Earth's largest predatory dinosaurs, including a strange tendency to small arms. increase.
On Thursday, scientists found a previously unknown species called Meraxesgigas, including one of the most complete skulls of a large carnivorous dinosaur ever unearthed in northern Patagonia. He said he had found a wide range of skeletal relics. Living in the Cretaceous period about 90 million years ago, Melax was about 36-39 feet (11-12 meters) long and weighed about 9,000 pounds (4 metric tons).
All meat-eating dinosaurs belonged to a bipedal group called theropods. Meraxes was a member of the theropod lineage called carcharodontosaurs (so-called shark tooth dinosaurs), which also contains a larger Giganotosaurus from Patagonia and a Carcharodontosaurus from Africa.
According to Juan Ignacio Canale, a paleobiologist at CONICET, an Argentine research institute at the Ernesto Buckman Museum of Paleobiology, Melax's skull is over 4 feet (127 cm) long and has been published in the journal Current Biology. The lead author of the research. https://www.cell.com/current-biology/fulltext/S0960-9822(22)00860-0.
"Many of the roof bones of the face and skull were covered with ridges, ridges and grooves, giving them an unpleasant look like a medieval gargoyle," said University of Minnesota. Said the paleobiologist and co-author of the study. Pete Mako Vicky.
Named after the dragon in the "Song of Ice and Fire" fiction series that influenced the TV show "Game of Thrones," the Melax has 6-inch (15 cm) serrated teeth. The largest toe claw of one of the big theropods.
"A terrifying sight," said Sebastián Apesteguía and Felix de Azara Foundation of CONICET, paleobiologists and co-authors of the study.
Despite its large body size, its arms are just over 2 feet (60 cm) long and "extremely short," Makovicky said.
Two other Cretaceous theropod strains – tyrannosaurs including T. rex in North America and abelisaurs including Carnotaurus in South America – have evolved stubby arms.
Due to the imperfections of the debris of other large carcharodontosaurs, Meraxes provided the first evidence of a decrease in the forefoot of this group. Abelisaurs had a hand with four fingers, but carcharodontosaurs reduced it to three and tyrannosaurs reduced it to two.
Scientists wondered why three of the most important cellopod groups independently evolved short arms that were of little use in predation. Researchers have shown that all three tend to increase head size and decrease forefoot size, suggesting that they rely heavily on the skull to kill their prey.
Despite its small size, Melax's arms were sturdy and muscular.
"Despite its powerful appearance, it's hard to imagine it being used a lot because it barely stretched and couldn't reach the huge mouth," Makobicky said.
"I tend to think it was used for other types of activities, such as hugging a woman during mating and helping her lift her body out of a prone position," Canale added. rice field.
Some other strains of large theropods did not join the trend. A giant spinosaurus with an elongated skull suitable for hunting aquatic prey had medium-length arms. The strange Therizinosaurus and Deinocheirus had a different diet than other theropods and boasted relatively long arms with huge claws.
Carcharodontosaurs peaked in diversity about 90 million years ago and then suddenly disappeared.
Meraxes is not the largest in this lineage, but its wreckage is the most complete of the largest carcharodontosaurs, with almost the entire skull, hips and limbs filling the gap in understanding of this group. increase.
For example, based on the dimensions of the Meraxes skull, researchers recalculated the Giganotosaurus skull length by a whopping 5-1 / 2 feet (168 cm). The largest Giganotosaurs in this lineage was slightly longer, but not as heavy as the Tyrannosaurus rex, which lived tens of millions of years later.
Apestegia, a dinosaur of this pedigree, said, "It's a mysterious beast for us."
(Report by Will Danham of Washington, edited by Rosalva O'Brien)
