When scientists first unearthed fossils of a horned dinosaur called Centrosaurus in the badlands of Dinosaur Provincial Park in Canada's Alberta province in 1989, they spotted a badly malformed leg bone they figured was a healed fracture.
A fresh examination, researchers said on Monday, shows something different. The malformation was a manifestation of osteosarcoma, an aggressive bone cancer, making this Centrosaurus, which lived 76 million years ago, the first known example of a dinosaur afflicted by malignant cancer.
About 20 feet (6 meters) long, Centrosaurus was a four-legged beaked plant-eating Cretaceous Period dinosaur possessing a long horn above its nose and a bony frill above its neck with two smaller hooked horns.