Left: young man with curly hair laying down on the floor, surrounded by huge bones. Right: man holding a bone with one hand and pointing to it with the other while explaining something.
Pasha van Bijlert. Photo on the left by Hanneke Jacobs. Photo on the right by Henk Caspers.

What You Think You Know About the T-Rex Is Wrong

"In films like 'Jurassic Park', the dinosaur was painted as a monster, when it wasn’t,” says palaeontologist Pasha van Bijlert.

This article originally appeared on VICE Netherlands.

Jurassic Park obsessives look away: the Tyrannosaurus Rex – arguably the most feared and awe-inspiring dinosaur of all – potentially wasn’t all that.

Researchers at the Dutch institute and museum Naturalis recently discovered that the T-Rex waddled around the late Cretaceous period (about 68 million years ago) at less than 5km an hour. That’s about the pace of a human walking, slowly


“Walking at 4.6km per hour isn’t slow – it’s normal for an animal,” said Pasha van Bijlert, the specialist who made the discovery. Bipeds like ostriches and humans prefer walking between 4 to 5km per hour, and the same goes for four-legged animals like horses and gazelles.

“But once a gazelle has a cheetah on its heels, it can easily speed up to 90km per hour,” said van Bijlert. “Walking speed is more about an animal’s overall laziness. Why run if you don’t have to?” He hasn’t attempted to calculate the T-Rex’s top speed yet, but another study suggests it could be between 20 and 29km an hour, which is still pretty slow.

Pasha van Bijlert - young man handling large bones part of a dinosaur’s feet and smiling at camera.

Trix being put together. Photo by Hanneke Jacobs

Van Bijlert, 27, started out his adult life as a medical student. One day, while bored in class, he read a news article about the excavation of a T-Rex skeleton named Trix, which is now on display at the Naturalis museum in Leiden. Inspired by the palaeontologists involved in the project, he realised he had to follow his passion, so he quit medicine and enrolled to study the science of human movement.

But van Bijlert never forgot about Trix – even his professors knew about his fascination. Towards the end of his degree, they nudged him to look into how he could apply what he’d learned about human movement to better understand his favourite pre-historic animal. He then taught himself to build the 3D models that would help him simulate how Trix walked while she was alive. Back in 2018, he started collaborating with Naturalis for his Bachelor’s thesis, and he’s been working for them as a 3D specialist and anatomist ever since.


“Physics teaches us that things have a resonant frequency – once you find the right rhythm, you get a lot more movement with much less effort,” he said, while bouncing a small weight attached to the end of an elastic band. “When I let go of this weight, it bounces up and down. That’s its natural frequency. If I pick a different rhythm, too fast or too slow, I have to put a lot more effort in.” 

Similarly, when a T-Rex used to walk, its tail would move up and down, attached to its tail ligaments. “Assuming the rhythm of its steps is equal to its natural frequency, we can build a physical model and reconstruct its walking speed based on its tail movements,” said van Bijlert.

In a way, the researcher’s findings normalise the T-Rex as just another animal that used to walk the earth. “In films like Jurassic Park – which I’m a massive fan of – the dinosaur was painted as a monster, when it wasn’t,” van Bijlert said. “If you start to break down the mythology a bit, you can look at this incredible beast as an animal that existed within its own ecosystem. That’s what I enjoy and what we’re trying to do.”

For instance, the team is working on a scientifically accurate animation of a T-Rex walking towards the viewer. “In it, [the dinosaur] doesn’t resemble the monster we know from Jurassic Park,” van Bijlert said. “Some biologists I’ve shown it to said it almost looks cute. That’s when I thought, ‘Mission accomplished.’”

Pasha van Bijlert - young man sitting on the floor, aligning the bones of a large skull and smiling while looking down.

The skull of a Triceratops. Photo by Servaas Neijens.

According to van Bijlert, the palaeontology community is split in two. On one side there are the classic palaeontologists who love nothing more than digging up bones and measuring them so they can plug their findings into the evolutionary tree; on the other, there are researchers who are more interested in how the dinosaurs moved, behaved and related to their ecosystem.

Whenever people ask him what the purpose of studying dinosaurs is in the 21st century, van Bijlert replies that these creatures are often an important stepping stone in encouraging kids to wonder about the natural world at large. “I think people underestimate how much room studying dinosaurs creates to have a conversation about science,” he said. “Ultimately, a kid might not become a palaeontologist, unless they’re crazy like me, but maybe they’ll be a different kind of scientist. All thanks to a dinosaur.”

Besides, understanding how one of the largest bipeds that ever lived used to move can also help us figure out other issues in modern robotics, for instance. “When a human walks, they don’t fall over very often, and don’t use much energy,” van Bijlert said. “Robots, on the other hand, require much more energy to remain stable while walking because they don’t have elastic ligaments that store energy.” This problem already exists in small robots, but will only be amplified once we build larger machines. 

“So that’s one of the more outlandish ideas I have,” van Bijlert said. “I think I’ll soon be able to prove that dinosaur bodies facilitate movement in even more clever ways than human beings’.”