Did dinosaurs have cancer? Study finds proof of disease in a 77 million-year-old Centrosaurus fossil
A group of experts examining the remains of an unusual fossil made an exciting discovery: a plant-eating dinosaur that roamed the Earth 76 to 77 million years ago was struggling with a type of bone cancer. This discovery suggests that the dreadful disease did not spare the past life forms as well.
"Cancer is an ancient disease that essentially boils down to abnormal cell growth and regulation, and thus it is perhaps not surprising to see its history stretch back so far among species that have long been extinct," Seper Ekhtiari, an orthopedic surgery resident at Canada's McMaster University and co-author of the study, told MEA WorldWide (MEAWW). The fossil — the lower leg bone or the fibula — belonged to a horned dinosaur named Centrosaurus apertus. It was first identified in 1989 in Dinosaur Provincial Park in Alberta. But the bone was odd, leading some experts to reason that it was healing from a fracture. However, researchers from McMaster University and the Royal Ontario Museum were not convinced.
Ekhtiari explained that the bone had characteristics that did not support the fracture theory. "It should look like a bone out of chick leg (but much bigger). But it looks like a club as cancer eroded the top off the bone completely," Mark Crowther, Professor of Pathology and Molecular Medicine, told MEAWW. So a team of multidisciplinary specialists and medical professionals took a closer look at the bone. They attempted to diagnose the condition similar to how experts detect an unknown tumor in a human patient. The team deployed a high-resolution imaging tool called computed tomography (CT) scans to examine the bone. Reconstruction tools helped them learn about cancer's progression through the bone.
The dinosaur was diagnosed to have osteosarcoma, a type of cancer caused due to abnormal growth in bone cells. It mostly forms in the legs and sometimes in the arms. In humans, it is more prevalent among teenagers and younger adults. "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." You can find a video here. To investigate further, the experts compared this malformed sample with a normal one from the same species. They also matched it with the fibula of a 19-year-old man diagnosed with osteosarcoma.
"The shin bone shows aggressive cancer at an advanced stage. The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable Tyrannosaur predators of the time," Dr David Evans, an expert on these horned dinosaurs, said. "The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease." However, there was one limitation. According to Ekhtiari, they did not have the rest of the individual’s skeleton. It "means we cannot determine whether it spread beyond this bone to other bones or other organs," he said, adding that they also could not estimate the age of the creature as a result.
Was cancer widespread among dinosaurs? Only further investigation will provide answers. "I suspect that other such bones will be found over time, Crowther said. Agreeing, Ekhtiari added: "We certainly expect that there are other cases of osteosarcoma, and other malignant cancers, among dinosaurs." The study raises other questions, including whether cancers that we see today behaved similarly in dinosaurs or not. "It would be interesting to understand whether osteosarcomas were more prevalent among dinosaurs due to their very rapid rates of bone growth," Ekhtiari explained.
The study is published in The Lancet Oncology.