T.REX developed tiny arms to stop them getting bitten off by rivals during pack feeding frenzies, an expert says.
The fearsome beast’s ancestors had much longer forelimbs but they shrank over time.
It meant they were not such an easy target in a scrap for the best pickings when T-Rexes converged on a carcass.
Paleontologist Prof Kevin Padian said: “You have a bunch of massive skulls, with incredibly powerful jaws and teeth, ripping and chomping down on flesh and bone right next to you.
“What if your friend there thinks you’re getting too close?
“They might warn you away by severing your arm.”
Experts have long been puzzled by T.Rex’s puny 3ft forelimbs.
But California-based Prof Padian dismissed earlier theories they were for balance, feeding or mating.
Instead, he thinks a bite on the arm from a rival would have caused deadly infection, haemorrhaging and shock.
Everton and England ’keeper Jordan Pickford is mocked by rival fans for having short T.Rex arms.
Earlier this year, the taunts sparked a pub brawl in South Tyneside.