See what a malignant dinosaur cancer looks like

A collaboration of scientists led by the Royal Ontario Museum (ROM) and McMaster University led to the discovery and diagnosis of an aggressive malignant bone cancer – osteosarcoma – in a dinosaur for the first time in the history of research. No malignant cancers have been reported in dinosaurs before. These are tumors that can spread throughout the body and have serious health consequences. The study was published by the medical journal The Lancet Oncology.

The cancer bone understudy – the fibula (lower leg bone) – belonged to a centrosaurus (a dinosaur of the Centrosaurus species), which lived from 76 to 77 million years ago. The severely distorted end of the fossil was initially thought to be a healing fracture. Scientists from McMaster University decided to continue the research using modern medical methods. They have assembled a team of interdisciplinary specialists and medical professionals in fields such as pathology, radiology, orthopedic surgery, and paleopathology.

Diagnosing aggressive cancers like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to identify correctly. Scientists have found unmistakable traces of progressive bone cancer in a 76-year-old horned centrosaurus – the first of its kind.



To confirm this diagnosis, they compared the fossil to a normal fibula from a dinosaur of the same species, as well as a fibula from a human with a confirmed case of osteosarcoma. The fossil sample was taken from an adult dinosaur with an advanced stage of cancer, which could have invaded other body systems. And yet he was found in a huge grave full of other dinosaur bones. This means that he, like a large herd of centrosaurs, died in the flood.

The lower leg shows aggressive advanced cancer. Cancer would have disastrous consequences for this centrosaurus and would make it highly vulnerable to the formidable tyrannosaurs of the time. The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than usual with such a devastating disease, scientists conclude.