The walking speed recorded by the powerful predator of the Jurassic Tyrannosaurus Rex was equivalent to what we present today, about 4.6 kilometers per hour, according to a new study.
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Humans and animals have a preferred speed when walking. This is, in part, influenced by the amount of energy required: they prefer to walk at the speed at which they use the least amount of energy possible.
One of the ways to achieve this is by using the resonance between speed and rhythmic movement of the body.
This works for animals that walk on all fours and for two-legged animals like humans and ostriches.
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Pasha van Bijlert, a Human Movement Sciences student at the Vrije Universiteit in Amsterdam (VU), applied the idea to an animal that walked differently than anything that walks on earth right now: Tyrannosaurus rex.
These carnivorous dinosaurs not only had two legs, they also had a huge tail that helped them move.
Like the bones of our neck, the bones of the tails are held together by ligaments.
“It can be compared to a suspension bridge,” explains Van Bijlert. “A suspension bridge with a ton of muscle.” At each step, the tail sways up and down. That means, like rocking, it has a natural frequency that it resonates at. “
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To find out what that frequency is, Van Bijlert and his professors Anne Schulp (Naturalis / Utrecht University) and Knoek van Soest (VU) built a 3D model of Trix, the Tyrannosaurus rex that is on display at the Dutch National Museum of Natural History.
They added digital muscles to the famous skeleton, and on this muscle model they were able to perform biomechanical analyzes. From these, they derived the natural frequency and a preferred walking speed: 4.6 km / h (2.9 mph). So when Trix was out for a walk, she was walking at roughly the same speed as a human.
Van Bijlert, Van Soest, and Schulp published their findings in the Royal Society Open Science journal. “There were already some studies looking at the walking speed of dinosaurs, but they mainly looked at the legs and ignored the tail, which is what makes dinosaurs so unique,” says Van Bijlert.
“They generally found much higher walking speeds. The one we calculated is lower, but it’s similar to other animals.”