A dinosaur had bone cancer 76 million years ago

A team led by researchers at McMaster University examined a malformed lower leg bone from Centrosaurus apertus, a horned plant-eating dinosaur that lived in what is now Alberta, Canada, about 76 million years ago.

Using CT scans, thin-section histology, and a side-by-side comparison with modern human osteosarcoma cases, the team confirmed the growth was an aggressive, advanced-stage malignant bone tumor, not a healed fracture or an infection as earlier guesses had suggested. It is the first osteosarcoma ever diagnosed in a dinosaur.

The dinosaur likely lived with the cancer for some time, since the bone shows signs it kept bearing weight despite the tumor, though it was found in a mass bonebed, suggesting it died with its herd, likely in a flood. The case shows that cancer biology itself has not changed much in tens of millions of years.

Cancer is older than we are.