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Tyrannosaurus rex may not have used their small front arms much, a new study of the most complete and best-preserved skeleton of the fearsome predator suggests.
Tests on arms of Sue the Tyrannosaurus rex at Argonne National Laboratory in the US show few signs of stress, researchers said.
The study by researchers at The Field Museum in Chicago suggests that when this fearsome predator was alive over 65 million years ago, she did not use those tiny arms very often.
"It's very early yet, but it seems like there are not many signs of stress on the bones that would indicate frequent use," Peter Makovicky, associate director of dinosaurs at the museum said.
"Based on what we know now, it looks like T rex did not use its arms much, at least not as an adult, but there is still a lot to learn," said Makovicky.
T rex's comically small front limbs have long stumped scientists.
Many have argued that the arms had a purpose, pointing out that the bones are short but thick and could have supported bulging muscles.
Others believe the arms were basically vestigial or a small remnant of an ancestor.
Skeleton of Sue the T rex was unearthed in Montana in 1990. She is 12.3 meters long and four metres tall, and her skull alone weighs 270 kilogrammes, 'Live Science' reported.
Sue's jaw is pockmarked with holes that may have been caused by a parasitic infection. If so, the disease was serious and may have killed the mighty predator.
However, it is Sue's arms that are getting all the attention.