The dinosaur that welcomes visitors to the Natural History Museum harbors a fascinating history. Researchers have identified a severe bone infection in the dinosaur, which lived around 220 million years ago in Switzerland and met a sticky end in the mud.
During the Late Triassic period, some 220 million years ago, a nearly eight-meter-long Plateosaurus roamed among the giant horsetails that stood two meters tall in what is now the Frick Valley in the canton of Aargau. The dinosaur got stuck in the mud, which was a common cause of death for its kind.
At that time, the Frick area resembled a playa; a large, flat depression within a semi-arid basin susceptible to flooding. This created large mud traps in which many of these animals would perish. However, this particular dinosaur’s odds of escaping the sticky mud were even lower than usual, as it suffered from a major bone infection that rendered its right arm useless.
In 2018, the almost complete skeleton of this dinosaur was discovered in the Frick valley. Plateosaurus trossingensis would have walked on its two hind limbs and is a forerunner of the iconic giant long-necked, long-tailed sauropods, such as the famous Diplodocus.
It was excavated and prepared as a prominent exhibit for the new Natural History Museum of the University of Zurich (UZH) to replace Meggie the Megatherium, a popular but scientifically inaccurate reconstruction of an ancient giant sloth.
Deep-dive into the dinosaur’s bone structure
Researchers at the Department of Paleontology, the Natural History Museum of UZH, and the Frick Dinosaur Museum have now described the skeleton and studied the chronic disease affecting its right shoulder and upper arm. For a glimpse inside the fossil, the team used computed tomography (CT). The work is published in the Swiss Journal of Palaeontology.
But which CT scanner could accommodate a dinosaur’s limbs? At the Swiss Federal Laboratories for Materials Science and Technology (Empa) in Dübendorf, luckily, an array of CT equipment was available—including 3D micro CT scanners and a 2D fan-beam Linac scanner capable of scanning samples measuring up to 70 x 200 cm and weighing up to one ton—perfect for the dinosaur’s upper arm and shoulder bones. The team identified the disease as likely a very severe case of osteomyelitis, an infection of the bone tissue.
“Osteomyelitis affects many living animals, including mammals such as humans, as well as birds and reptiles,” explains 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. 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.”
This discovery is fascinating not only because, at around 220 million years old, it is currently the oldest reported case of osteomyelitis in a dinosaur, but the size of the infected area was unusually large.
“Previous studies of osteomyelitis in dinosaurs report localized areas of infection, such as toe bones or a couple of adjacent bones in the spine,” explains Jordan 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.”
Pride of place at the Natural History Museum
The specimen, which has since been nicknamed “Teoplati” in a public naming competition, now welcomes the numerous visitors to the Natural History Museum of UZH. Prominently placed at the entrance of the museum, the skeleton lies in its original pose, with a towering life-size reconstruction next to it.
Dennis Hansen, from the Natural History Museum, who led the creation of the exhibit, says, “We wanted a display that highlights the tragic story of this particular animal.” The life-size reconstruction stands upright in front of a small landscape diorama. Footprints in the drying mud record some of the dinosaur’s final steps before it broke through the cracked surface to meet its muddy fate.
“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,” says Hansen.
“This makes the display one of the few worldwide where the reconstruction of an individual dinosaur includes its pathologies.” A fitting tribute to this iconic, early large dinosaur.
More information: Sina F. J. Dupuis et al, Osteology and histology of a Plateosaurus trossingensis (Dinosauria: Sauropodomorpha) from the Upper Triassic of Switzerland with an advanced chronic pathology, Swiss Journal of Palaeontology (2025). DOI: 10.1186/s13358-025-00368-3
Provided by University of Zurich