The Tyrannosaurus rex is one of the most well-represented and most well-known species of the large theropod dinosaurs, but despite its ferocious and fearsome nature, the T. rex is always the target of dinosaur jokes in movies and TV shows because of its tiny arms. It couldn't claw or grab the bodies of its prey, but that doesn't mean it couldn't do anything else.
Aside from its thick, heavy skull, its huge head and its wide, gaping bite, the T. rex has a whip-like tail and legs too long for its body.
Hypothetically, if dinosaurs like the T. rex were alive today and you had to outrun one, will you even succeed? The answer, of course, depends on how you plan to outrun the hungry beast. If you had to do it barefoot, you're probably not going to last long.
If You Were To Outrun A Dinosaur, Do The Math First
If you think about it, the "Jurassic Park" movies often involve dinosaurs running rampant. Aside from the scary T. rex, one of the dinosaurs that received particular exposure were the velociraptors.
Velociraptors, or speedy thief, are thought to reach the average speed that cheetahs perform, which is around 50 to 60 mph.
However, scientist Scott Persons of the University of Alberta said this concept is inaccurate.
"They're actually among the least adapted for speed. Whatever their hunting strategy was, chasing down prey like a cheetah was just not part of it," said Persons.
Persons and Philip J. Currie, his advisor, decided to study the length of the legs of 53 species of theropods, including the T. rex, the velociraptor and the allosaurus.
The duo devised a mathematical formula that can distinguish how well an individual theropod species was built for speed. Their findings are featured in the journal Scientific Reports.
Persons said that for animals to become fast runners, their lower leg should be relatively long from the knee down. The longer the lower leg is when compared to the upper leg, the faster the animal.
However, long legs are not good for supporting animals with massive bodies. Over time, an animal that evolves faces two opposing forces: the need for traveling over distances in the shortest time possible or the need to support body mass.
Persons said what needs to be factored out is the allometric influence, or the influence of the animal's body size to its shape, physiology, anatomy and behavior.
Persons and Currie's equation determines the dinosaur species' cursorial limb proportion score, or the extent to which its legs are used for longer or shorter running.
By taking into account the body weight of the dinosaur, the duo calculated the length of the animal's lower leg, and then compared it to the length of the actual leg.
In the end, Persons and Currie learned that early theropods had lower scores than their more-advanced relatives. These predators had evolved over time to become faster when hunting prey, they said.
"It looks like there was a general push throughout theropod evolution to get faster," said Persons.
What's fascinating is that velociraptors were among the theropods that obtained the lowest cursorial limb proportion scores, getting -13.2. For the T. rex, it was +11.5.
The Nanotyrannus
Interestingly, Persons applied their equation on a fossil specimen of the controversial Nanotyrannus. He found that the animal had a cursorial limb proportion score of +35.8.
This suggests that the Nanotyrannus is a unique species, and doesn't conform to the pattern in other theropods. The Nanotyrannus was probably highly adapted for running.
"I like to say that Nanotyrannus is the cheetah to T. rex's lion," said Persons.
Let's Wind Back To The T. Rex Question
The research also looked into the rare footprints of a young T. rex. The footprints, fossilized in sandstone in Wyoming, probably date back 66 million years ago.
It revealed that the young T. rex had a gait of 2.8 to 5 miles per hour. This is slower than the average human who can run about 11 miles per hour over short distances.
In this case, however, the T. rex is only walking, and on muddy, mucky terrain, said Persons. He said it was clearly a walk and not a run because of how the feet were positioned.
Persons and Currie's findings discount other studies that say the T. rex was notably slower than other dinosaurs.
Still, there is still no consensus as to what the exact speed of the T. rex really was. And if it's already running after you, thinking about the fastest way to save your own life should probably be your priority.
