Ancient Dinosaur Exhibits Rare Chronic Bone Infection from Triassic Epoch

Paleontologists at the University of Zurich have uncovered a remarkable case of chronic osteomyelitis, a severe bone tissue infection, in the fossilized remains of *Plateosaurus trossingensis*, one of the earliest known dinosaurs from the Late Triassic period of Europe. This significant discovery, reported in a study published on June 17, 2025, in the *Swiss Journal of Palaeontology*, highlights the complexities of disease in prehistoric life and provides new insights into the health issues that affected these ancient creatures approximately 220 million years ago.

*Plateosaurus trossingensis*, which could reach lengths of up to 8 meters (26 feet) and primarily walked on its hind limbs, thrived in what is now modern-day Switzerland during the Late Triassic epoch. The fossil examined by Dr. Jordan Bestwick and his team originated from the Klettgau Formation in Frick, Switzerland, where it was found to exhibit severe signs of osteomyelitis in the right shoulder and upper arm, suggesting a chronic condition that could have plagued the dinosaur for a considerable portion of its life.

According to Dr. Bestwick, a paleontologist at the University of Zurich and lead author of the study, "Osteomyelitis affects many living animals, including mammals such as humans, as well as birds and reptiles. This disease has been documented in several dinosaur groups, including sauropods, allowing us to compare our findings with a range of specimens."

The research team noted that the affected bones displayed abnormal textures, altered shapes, and signs of fusion, all of which are characteristic of osteomyelitis. Dr. Bestwick emphasized the uniqueness of this case, stating, "While previous studies typically report localized infections, such as in toe bones or a few adjacent vertebrae, our findings of an entire infected shoulder and upper arm are notably unusual."

Although the specific cause of the infection remains uncertain, the implications of such a chronic condition on the dinosaur's mobility and overall health were significant. Dr. Bestwick suggested that this infection may have rendered the dinosaur's right arm largely unusable, potentially impacting its ability to forage or defend itself.

The significance of this discovery lies not only in the rarity of the findings but also in what it reveals about the life and health of *Plateosaurus trossingensis*. This case is currently the oldest reported instance of osteomyelitis in a dinosaur as per the fossil record. The team’s findings add to a growing body of evidence that prehistoric animals faced similar health challenges as modern species, raising questions about the prevalence and impact of diseases in ancient ecosystems.

In summary, the discovery of osteomyelitis in *Plateosaurus trossingensis* provides valuable insights into the health conditions of dinosaurs and their evolutionary responses to disease. As research in paleopathology continues to evolve, it opens avenues for understanding the intersection of biology and environment in ancient times, shedding light on how these magnificent creatures adapted to their surroundings and the challenges they faced. The ongoing study of such fossils may ultimately enrich our understanding of the evolutionary history of diseases, linking past and present in the study of biology and health.