Previous research suggested the king of the dinosaurs could run up to 45 miles per hour, almost 20mph faster than Olympic gold medalist Usain Bolt.
But scientists have now discovered it would have been impossible for the T-Rex to run that fast without breaking its legs, due to its sheer size and weight.
A study from Manchester University found the 20 foot tall beast would have clocked a top speed of about 12mph, 3mph slower than the average human, and less than half the speed of Usain Bolt’s personal best of 27.8 mph.
Researchers used an engineering technique called multibody dynamic analysis, coupled with machine learning, to produce what they say is the most accurate simulation of T-rex’s gait and biomechanics to date.
In a paper published in the journal PeerJ, Professor William Sellers said that if it were to go any faster, its nine ton weight would be too much for its legs to handle.
Professor Sellers said: “The running ability of T Rex and other similarly giant dinosaurs has been intensely debated amongst palaeontologist for decades.
“Here we present a new approach that combines two separate biomechanical techniques to demonstrate that true running gaits would probably lead to unacceptably high skeletal loads in T Rex.”
Because of its size and weight, the predator would actually have broken its legs had it tried to break into a sprint, the University of Manchester research showed.
Professor Sellers said: “The muscles need to be able to generate sufficient power to allow high-speed locomotion, but at the same time the skeleton has to be able to cope with the loads generated by the high speed.
“This is where it fails. T-rex’s skeleton is simply not strong enough for running locomotion.”
Professor Sellers said his study had forced a re-think on how T-Rex caught its prey.
He said: “It certainly would not have been able to chase down faster-moving prey animals.
“That leaves other hunting options such as ambush, and of course it means that discredited ideas such as ‘T-Rex the scavenger’ have to be reconsidered.”
A separate study, which compared the speeds for various dinosaurs, found the T Rex could potentially reach a top speed of 16.8 MPH.
However, if dinosaurs were roaming the Earth today, it would be the velociraptors which you would have to watch out for, which could get an average speed of 33.6 MPH.
In this study published in Nature Ecology & Evolution, the researchers wrote: “Palaeontologists have long debated the potential running speeds of large birds…