In one of the most iconic scenes in Jurassic Park, Ellie Sattler and Ian Malcolm cling on to a Jeep as they are chased by a fearsome Tyrannosaurus rex. But would a T. rex really be able to outrun a Jeep as it raced down a jungle path? Probably not, new research suggests. 

The size and weight of the massive predator means the T. rex would not have been able to run. Rather than clocking up speeds that could outpace a car, the beasts likely only reached walking speeds of around 5 meters per second (18 kph/11 mph), meaning that even on foot, a human may have been able to outrun it. The paper, published in PeerJ, suggests that any higher speed would have simply buckled the animal's legs.

“The running ability of T. rex and other similarly giant dinosaurs has been intensely debated amongst palaeontologist for decades,” says lead author Dr William Sellers, from the University of Manchester, in a statement. “However, different studies using differing methodologies have produced a very wide range of top speed estimates and we say there is a need to develop techniques that can improve these predictions.”

^{Computer modeling of the stress on a T. rex skeleton. University of Manchester)}

This time round, Dr Sellers and his team combined two separate biomechanical techniques – multibody dynamic analysis and skeletal stress analysis – to model more accurately how the giant dinosaurs would have plodded along. They found that if the T. rex were to try and break out into a run, it would have likely broken its leg bones.

The results of this latest bout of research also feeds into one of the longest running palaeontological debates that has played out regarding the lifestyle of the bipedal predator. For awhile, there were two camps when it came to how the beasts behaved: one argued that the animal was an active predator hunting down its prey with ferocity, while the other claimed that it was more of a scavenger.

This work seems to suggest that the latter camp may be closer to the truth, though to be fair it is not – and has never been – an either/or situation. There is nothing to say that it couldn’t have hunted some of the slower-moving herbivores around at the time, while simultaneously picking up scraps as it moved through the subtropical landscape.

What's more interesting is what can be inferred about the differences in behavior between younger tyrannosauruses and the older ones. Some studies have suggested that as the animals grew, their torsos got longer and heavier as their limbs became proportionally smaller. This would have meant that while the adults may have been more lumbering, the juveniles might have been a little more spritely. Sellers, however, says this probably wouldn’t have been the case.