University of Alberta graduate student Scott Persons says T. rex's long tail, rather than just serving as a counterbalance for the beast's big head, contained hugely powerful muscles allowing it to run at an impressive speed, ScienceDaily.com reported Tuesday.
"Contrary to earlier theories, T. rex had more than just junk in its trunk," Persons says.
Persons compared the tails of modern-day reptiles, such as crocodiles and Komodo dragons, to T. rex's tail, and found that for all animals in his study, the biggest muscles in the tail are attached to upper leg bones.
These caudofemoralis muscles provide the power stroke, allowing fast forward movement, Persons says.
Extensive measurements of T. rex bones and computer modeling show previous estimates of the muscle mass in the dinosaur's tall were underestimated by as much as 45 per cent, he says.
That led earlier T. rex researchers to believe the animal lacked the necessary muscle mass for running, casting T. rex in the role of a scavenger only able to survive by feeding on animals killed by other predators.
Persons says T. rex's actual speed is hard to determine but he says he's convinced it could probably run down any other animal in its ecosystem.