220-million-year-old Plateosaurus dinosaur died from a crippling bone infection

Every visitor to the Natural History Museum in Zurich is greeted by a massive dinosaur skeleton nicknamed “Teoplati.” At first glance, it looks like any other prehistoric fossil on display, except for the presence of a serious bone infection.

Teoplati’s story is anything but ordinary.

This eight-meter Plateosaurus, which lived 220 million years ago in what is now Switzerland, met its end in sticky mud – and researchers say it was already struggling long before that. The dinosaur’s right arm, it turns out, was badly infected.

Scientists from the University of Zurich, along with researchers at the Frick Dinosaur Museum, recently studied the fossil and uncovered one of the oldest – and most severe – cases of bone infection ever recorded in a dinosaur.

Mud-bound dinosaur had a useless arm

Back in the Late Triassic epoch, the Frick Valley in Aargau was a flat, dry landscape prone to sudden flooding.

Picture a massive clay pit in a semi-arid basin – perfect for trapping large animals like Plateosaurus. Many of these dinosaurs likely died the same way: caught in the mud with no way out.

But this particular Plateosaurus had even worse odds. It was already injured.

The dinosaur’s right shoulder and upper arm were severely damaged by a chronic infection.

When researchers examined the bones, they found signs of intense inflammation and deformation – evidence that the animal’s limb had been unusable long before it became stuck in the mud.

CT scanners detect dinosaur bone infection

The nearly complete skeleton was unearthed in 2018. Paleontologists from the University of Zurich began studying it closely, especially the damaged limb.

To get a better look inside, they used high-tech CT scanners at Empa, the Swiss Federal Laboratories for Materials Science and Technology.

These scanners, typically used for industrial research, were the only machines large enough to handle the dinosaur’s massive bones.

What they found was striking. The Plateosaurus likely suffered from osteomyelitis – a serious infection that attacks bone tissue.

Osteomyelitis is still common today

“Osteomyelitis affects many living animals, including mammals such as humans, as well as birds and reptiles,” explained Jordan Bestwick, postdoctoral fellow at the Department of Paleontology at UZH.

“This disease is known to have affected several different dinosaur groups, including sauropods, so we had access to a range of specimens to compare our Plateosaurus with.” said Bestwick.

“The affected bones in the shoulder and upper arm have unusually rough internal and external textures, altered shapes, and are even fused together – symptoms that are broadly typical of osteomyelitis.”

What makes this case so unique is the size of the infected area.

“Previous studies of osteomyelitis in dinosaurs report localized areas of infection, such as toe bones or a couple of adjacent bones in the spine,” explained Bestwick.

“Having an entire infected shoulder and upper arm is very unusual. Although we don’t know what initially caused the infection, the animal likely suffered from this disease for a substantial part of its life, possibly rendering its right arm useless.”

Jurassic infection links dinosaurs and humans

Today, Teoplati stands tall at the entrance of the Natural History Museum at the University of Zurich.

The skeleton lies in the exact position in which it was found. Next to it stands a life-sized reconstruction that shows what the animal may have looked like in life – including the deformed right arm.

Dennis Hansen, who led the exhibit’s creation at the museum, said the display tells more than just a biological story – it’s a personal one. “We wanted a display that highlights the tragic story of this particular animal,” said Hansen.

The exhibit includes a diorama of cracked mud and footprints – some of the dinosaur’s last steps – before it sank beneath the surface.

“Together with the paleo-reconstruction wizards from the Danish company 10 Tons, we created a reconstruction based on the skeleton that also showcases the disease on its right arm and shoulder,” said Hansen.

“This makes the display one of the few, worldwide, where the reconstruction of an individual dinosaur includes its pathologies.”

In other words, it’s not just a dinosaur. It’s a story of injury, survival, and an unlucky end. Visitors walking into the museum aren’t just meeting an ancient creature – they’re meeting an individual with a history written in its bones.

The full study was published in the journal Swiss Journal of Palaeontology.

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