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How fast did T. rex walk?

By , 27 May 2021

Skeleton of T-rex

Trix the Tyrannosaurus walked at a leisurely pace
Image: Mike Bink Fotografie

Are you faster than a Tyrannosaurus rex? Scientists are still arguing about how fast a T. rex could run, if it could run at all. But most animals walk more than they run. So how fast is a tyrannosaur’s walking speed?

There’s a reason why animals walk at the speed they do. Look at humans as an example. When people walk at a comfortable pace, they might find their arms swinging. That’s no accident! When our stride matches the swing of our arms, energy can move easily between the two. Our bodies can store a bit of walking energy in the arms, and this makes walking more efficient at that speed.

Back to the Tyrannosaurus. T. rex’s arms are famously small and useless, but there’s a much bigger part of a Tyrannosaurus that swings – its tail!
A team of Dutch researchers were on the case. They started with a particularly well-preserved skeleton, nicknamed Trix. The fossils of Trix’s tail don’t just preserve its bones – they also include parts of the ligament that helped hold the tail together.

By using scans of the bones and adding digital ligaments, the team built a 3D model of Trix’s tail. Then they found the speed that it would naturally swing at. This revealed the time it took for Trix to take a step.
To calculate a final speed for Trix, they also needed to know the distance each step covered. Luckily, there are many T. rex footprints that have been fossilised. The team took measurements from a smaller T. rex’s tracks and scaled them up to estimate Trix’s stride.

Combining these two numbers, the team were able to estimate Trix’s walking speed. This 12-metre-long beast probably walked at about 4.6 kilometres per hour, roughly a human’s walking pace. So you could walk a Tyrannosaurus at a similar pace to a dog – just be careful when playing fetch!

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