Roughly 76 million years ago, a Centrosaurus that lived in what is now Canada was walking around with a malignant tumour in its lower leg, found scientists based on its deformed fossil bone.
The cancer was diagnosed osteosarcoma and this is the first time that cancer has been confirmed in a dinosaur, although scientists have identified benign tumours in Tyrannosaurus rex fossils in the past.
Researchers say that the tumour could have eventually been fatal, but the Centrosaurus probably died in a flood with the rest of its herd.
This deformed bone had a malignant tumor in the dinosaur fossil of partial fibula—a bone from the lower leg—belonged to a horned, plant-eating Centrosaurus that lived about 76 million years ago in what is now Dinosaur Park in southern Alberta in Canada.
Paleontologists initially thought the bone was deforemd due to a fracture but a new study, published in The Lancet Oncology, found it after comparing it with a bone tumor from a human patient. The osteosarcoma cancer primarily attacks teens and young adults and causes tumors of immature bone tissue, frequently in the long bones of the leg.
Similar cancer diagnosis in dinosaurs
In the past such a tumor was found in Tyrannosaurus rex fossils and arthritis in duck-billed hadrosaurs, as well as an osteosarcoma in a 240-million-year-old turtle but they were benign. The present study is the first to confirm a dinosaur cancer diagnosis at the cellular level.
Scientists examined the full fossil with high-resolution computerized tomography scans and examined thin sections under the microscope to find the tumor advanced enough that it had probably plagued the animal for some time.
A similar case in a human, left untreated, would be fatal, they wrote. However, because the fossil was found in a bone bed with lots of other Centrosaurus specimens, the dinosaur likely died in a flood with the rest of its herd and not from the cancer, they said.