The discovery of dinosaurs related to Tyrannosaurus rex has led researchers to speculate that their tiny arms were used in the mating process.
One study said that Meraxes gigas was unearthed in Argentina and is believed to have weighed about 4 tons.
Its discovery has helped scientists understand some of the uses short-armed arthropods may have had on their tiny forelimbs.
“I believe those proportionately tiny arms have some function,” said Juan Canale, lead author of the study.
Mr. Canale, of Argentina’s CONICET research agency, says that although the arms are too short for hunting, “I tend to think they are used in other types of activities, like holding a female while mating or helps raise the body. from a prone position.”
Meraxes lived about 90 million years ago during the Cretaceous period.
Despite being about 12 meters long, the creature has front limbs that are only 60cm long.
Meraxes were part of the group of bipedal, arthropod dinosaurs in the family Carcharodontosaurus – or toothed shark -.
Tyrannosaurus rex is another arthropod, part of the related group of tyrannosaurs.
Like its distant cousin, Meraxes has a rather large head – about 130cm long – that is “covered with bumps, ridges and grooves, giving it the odd appearance of a medieval shogun.” ancient”, according to paleontologist Pete Makovicky.
Previous discoveries of small-armed arthropods were not as complete as Meraxes.
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Scientists have long speculated why the tyrannosaurs, carcharodontosaurus and a third group known as abelisaurus had such small arms.
All three have large heads, indicating reliance on this to take down prey.
Researchers estimate that Meraxes’ arms were stout and muscular despite their large size.
Mr Makovicky, of the University of Minnesota, said: “Despite their strong appearance, it’s hard to imagine they’ve been used much as they barely extend beyond the body and can’t reach the huge mouth. “
Some arthropods, such as Spinosaurus, Therizinosaurus, and Deinocheirus have longer forelimbs, but they appear to have had a different diet from short-legged species.
The study was published in the journal Current Biology.