The first-ever evidence for a dinosaur that lived with a malignant, spreading caner has been discovered in a 77 million-year-old fossil, a study has reported.
Experts found the bone cancer — an osteosarcoma — in a horned plant-eating dinosaur, Centrosaurus apertus, that lived in Canada during the Cretaceous Period.
The lower leg bone — which was found in Alberta's Dinosaur Provincial Park in 1989 — had originally been thought to have become malformed by a fracture healing.
Scroll down for video
The first-ever evidence for a dinosaur that lived with a malignant, spreading cancer has been discovered in a 77 million-year-old fossil, pictured, a study has reported
Palaeontologist David Evans of the Royal Ontario Museum noted the bone's unusual properties during a visit to the Royal Tyrrell Museum in Drumheller, Canada, in 2017 — and set out with colleagues to analyse it with state-of-the-art medical techniques.
The team — which included specialists in the fields of pathology, orthopaedic surgery and radiology — approached their diagnosis of the bone's condition in exactly the same way that doctors would investigate a tumour in a human.
The team re-evaluated the bone and approached the diagnosis similarly to how it would be approached for the diagnosis of an unknown tumour in a human.
'Diagnosis of aggressive cancer like this in dinosaurs has been elusive and requires medical expertise and multiple levels of analysis to properly identify,' said paper author and pathologist Mark Crowther of the McMaster University in Ontario.
'Here, we show the unmistakable signature of advanced bone cancer in 76-million-year-old horned dinosaur — the first of its kind. It's very exciting.'
After carefully examining, documenting and casting the bone, the team performed high-resolution computed tomography (CT) scans of the fossil — before viewing thin slices of the bone under a microscope to study it at the cellular level.
Comparisons were also made between the cancerous bone and a normal lower leg bone, or fibula, from another dinosaur of the same species, as well as a fibula from a human with a confirmed case of osteosarcoma.
The researchers also used powerful three-dimensional CT reconstruction tools to visualise the progression of the cancer throughout the bone.
The team said that the fossilised bone belonged to an adult dinosaur with an advanced stage of the cancer that had likely invaded its other body systems.
Despite this, however, the specimen was found in a massive bone bed, suggesting that the Centrosaurus died as part of a large herd that was struck down by a flood.
Experts found the bone cancer — an osteosarcoma — in a horned plant-eating dinosaur, Centrosaurus apertus (pictured, with the affected bone highlighted) that once lived in Canada
The shin bone shows aggressive cancer at an advanced stage,' said Dr Evans.
'The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of