Could You Have Outrun a T. Rex?

February 1, 2016 | Joanne Kennell

Tyrannosaurus Rex (T. Rex)
Photo credit: Scott Kinmartin/Flickr (CC BY 2.0)

A rare set of footprints is giving researchers insight into their walking speed.

Picture this: You somehow travel back in time to the Cretaceous Period and you have a little run in with a T. rex.  It’s hungry and you look like a tasty meal — not a great way to start your day.  

What do you do?  You may be thinking, “Well if Jurassic Park taught me anything, it’s that a T. rex can’t see me if I don’t move, so I will just stand still.”

Bad idea!  T. rex actually had fantastic vision — 13 times better than humans.  So that beloved and intense scene in Jurassic Park with Dr. Grant just feet away from the dinosaur's mouth would have actually ended quite badly for the doctor.

So how did the question of outrunning a T. rex even come up?  A rare set of Tyrannosaurus rex footprints were recently discovered in Wyoming, giving researchers insight into the walking speed of the beasts.  According to their estimate, the Tyrannosaurus rex moved at a speed of approximately 8 kilometers per hour (5 miles per hour) — which is much slower than most human runners.  To put how slow this is into perspective, competitive speed walkers go between 8 and 9 miles per hour!

SEE ALSO: Titanosaurs: The Largest Animals to Ever Walk on Earth

The new trackway — which is a set of dinosaur footprints — was found in 66-million-year-old rocks that formed along an ancient shoreline in what is now Wyoming.  The first footprint was well preserved, with three toes facing forward and one short toe facing rearward. This arrangement of the toes means the prints belonged to a meat-eating theropod, and the only theropods known to have lived in the region 66 million years ago with feet this big were tyrannosaurs.

To figure out how fast it was moving, Scott Persons, a vertebrate paleontologist at the University of Alberta, Edmonton in Canada, and lead author of the new study, had to first estimate how high the dinosaur's hips must have been above the ground, based on the length of the footprint.  Using two common formulas, Persons and his team determined the beast’s hips were likely between 1.56 and 2.07 meters (5 to 7 feet) off the ground.

They then measured the distance between the footprints and used another equation based on observations of living, walking bipeds to estimate the dinosaur's walking speed — between 4.5 and 8 kilometers per hour (2.8 to 5 miles per hour).

However, the article posted in Science titled “You could probably have outrun a T. rex” should not have you wanting to attempt a race against one — there is more to the story according to The Huffington Post.

Although the researchers suggested that the spacing of these rare footprints indicated a maximum speed of 5 miles per hour, which is slower than the average human who can run 11 miles per hour over short distances, doesn’t mean the T. rex could not have gone faster.  Not to mention that these tracks were from an adolescent T. rex, not an adult.  

Not only that, the types of sediment that are best for preserving footprints are typically wet — not the best surface for a dinosaur to run full speed.  “There are as yet no known trackways of running tyrannosaurs, so we don’t know for sure just what their upper speed limit was,” Richard McCrea, a paleontologist at the Peace Region Paleontology Research Centre in Tumbler Ridge, Canada said to Science.

SEE ALSO: “Dinosaur Disco” Discovered in Scotland’s Largest Fossil Site Yet

"The tyrannosaur that made the footprints was just walking, and it was walking over muddy, mucky ground,” Persons said to The Huffington Post.  “And it was clearly a walk and not a run because of how the feet were positioned.”

Also, trackways are records of single events, so the odds that any set of footprints capturing a dinosaur's peak performance are slim, said Thomas Holtz Jr., a vertebrate paleontologist at the University of Maryland, College Park.

However, there is speculation on what a T. rex’s top speed could have been.  Some say it could only go about 10 miles per hour, while others say it could run 45 miles per hour.

Either way, I don’t think any of us would want to experience a face-to-face encounter with a Tyrannosaurus rex!

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