From the dinosaur link above:
The diagnosis? Osteosarcoma — an aggressive bone cancer — in the fibula, or lower leg bone, of a
Centrosaurus apertus,
a plant-eating, single-horned dinosaur that lived 76 to 77 million years ago.
The discovery opens up new understanding about other diseases that may have developed in dinosaurs, among other aspects of dinosaur life.
...the bone was discovered in 1989...by the
Royal Tyrrell Museum in Drumheller, Canada, discovering the fibula in
a massive bone bed in Alberta, Canada.