T-rex’s tiny arms were actually ‘vicious slashing’ weapons, suggests expert
Friday, November 03, 2017 9:06 pm[img]https://image.assets.pressassociation.io/v2/image/production/2cd9b350a58aef1801806e54b9581ed2Y29udGVudHNlYXJjaCwxNTA5ODI4MDMy/2.32947217.jpg?rect=1072,0,2428,1366&ext=.jpg[/img]
An expert paleontologist has claimed that the stubby arms of the Tyrannosaurus rex were actually vicious weapons.
Last year it was found that a separate species of dinosaur, the Gualicho shinyae, evolved the same puzzlingly small arms independently of the T-rex – suggesting the tiny limbs were not vestigial and stepping up efforts to deduce their purpose.
A paper by Dr Steven M Stanley, from the University of Hawaii, now suggests that T-rex’s seemingly comical arms were “not functionless but adapted for vicious slashing”.
[imgcap=(Owen Humphreys/PA)]https://image.assets.pressassociation.io/v2/image/production/9587c46652c6c1a5625ae4801f4be486Y29udGVudHNlYXJjaCwxNTA5ODI4MTY5/2.32947205.jpg?w=640[/imgcap]Stanley, who presented his findings at a meeting of the Geological Society of America in Seattle, said the evidence suggests the arms were very strong. Meanwhile, at a length only slightly longer than the leg of a 6ft man, they would have been ideal for close-quarter slashing – with huge damage caused by 10cm, sickle-shaped claws.
“Its short, strong forelimbs and large claws would have permitted T. rex, whether mounted on a victim’s back or grasping it with its jaws, to inflict four gashes a meter or more long and several centimetres deep within a few seconds,” wrote Stanley. “And it could have repeated this multiple times in rapid succession.”
Stanley explains that Tyrannosaur ancestors used their longer limbs for grasping, but a T-rex’s jaws replaced this function.
“No longer being selected for, the arms were selected against: the expansion of the head deprived them of nutrition in a zero-sum game,” said Stanley. “Then, as the arms approached their final size, natural selection kicked in opportunistically and put them to good use for slashing at close quarters.”
[imgcap=(Owen Humphreys/PA)]https://image.assets.pressassociation.io/v2/image/production/d9357bcd66328ce5846e1fddc2a1b84bY29udGVudHNlYXJjaCwxNTA5ODI4MzI4/2.18774806.jpg?w=640[/imgcap]Other experts at Stanley’s presentation are unconvinced however, with Jakob Vinther, from the University of Bristol, who attended, saying it was “illogical” to him.
He suggested the arms might have a more minor purpose, perhaps to hold on to a mate during sex – a claim Stanley indicated would be too dangerous given the claws’ sharpness.
It’s a debate that will rage on.