Using CT scans, researchers discovered a malignant bone cancer in the fibula of a horned dinosaur that lived 75 million years ago. Photo by Royal Ontario Museum/McMaster University
Aug. 4 (UPI) -- For the first time, scientists have diagnosed a dinosaur with osteosarcoma, an aggressive, malignant bone cancer, according to a study published in The Lancet Oncology.
The tumor was found on the fibula, or lower leg bone, of a Centrosaurus apertus specimen, a plant-eating, horned dinosaur that lived 75 million years ago.
Shortly after its original discovery in Dinosaur Provincial Park in Alberta in 1989, paleontologists misdiagnosed the cancer as a healed fracture. During a more recent survey of potentially pathological dinosaur bones, a team of researchers from Royal Ontario Museum and McMaster University spotted the error.
"The cancerous bone is severely malformed, with a massive gnarly tumor larger than an apple in the middle of the bone," study co-author David Evans told UPI.
Evans and his colleagues used high-resolution CT scans to identify the true nature of the malignant bone growth.
"We were not only able to demonstrate that the bone tissue showed the hallmarks of osteosarcoma, but that the tumor spiraled through the cortex of bone, discounting its original identification of a healed fracture and revealing it was an aggressive cancer," said Evans, the chair of vertebrate palaeontology at the Royal Ontario Museum.
Osteosarcoma is usually found in teenagers and young adults. Disorganized cells replicate rapidly, spreading through the bone and often spreading to other organs.
According to medical doctors on the project, the tumor finding supports the theory that osteosarcoma typically attacks areas of bone that are growing fastest.
"Studying the fossil record can give medical researchers insight into the antiquity and evolutionary origins of the cancers and other diseases that we see today," Evans said.
The tumor found in the Canadian dinosaur was so large that scientists suspect the cancer had likely spread throughout the animal's body by the time it perished.
"This particular Centrosaurus was likely weak and lamed by the cancer in its leg prior to its death," Evans said. "This would have made this individual Centrosaurus more vulnerable to the top predators of the time, fearsome tyrannosaurs that were cousins of Tyrannosaurus rex."
However, researchers estimate that the dinosaur's participation in a larger herd likely provided safety in numbers, allowing the Centrosaurus to avoid predation for longer than it would have on its own.