Researchers on Monday announced the discovery and diagnosis of an aggressive type of bone cancer in a dinosaur, making it the first known example of a dinosaur afflicted by malignant cancer, according to a study.

The cancer was found in the leg bone of a Centrosaurus, a horned dinosaur that lived 76 to 77 million years ago.

A team of researchers, including David Evans of the Royal Ontario Museum (ROM) and Mark Crowther a hematologist at McMaster University, re-evaluated the bone and determined it was actually osteosarcoma, an aggressive type of bone cancer, according to a study published the journal Lancet Oncology.

“Diagnosis of aggressive cancer like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to properly identify,” Crowther said in a press release by the ROM.

“Here, we show the unmistakable signature of advanced bone cancer in 76-million-year-old horned dinosaur -- the first of its kind.

Most tumors occur in soft tissue that doesn't willingly fossilize, so there is little evidence of cancer in fossil records, according to Reuters.

Tumors were also found in a dinosaur earlier this year, although a malignant cancer diagnosis has yet to be confirmed.

While the Centrosaurus was likely weak from cancer before it died, Evans said the disease may not have killed the dinosaur.