One of the most common bone cancers in humans, osteosarcoma, has recently been detected in dinosaur fossils. Some dinosaur bones inflicted with the disease date back to about 75 million to 66 million years ago.
Osteosarcoma, affecting about three out of one million people in the world, is typically seen developing around the knee or at the end of long bones. The cancer attacks cells which result in immature bone and on rare occasions occur in the soft tissue surrounding the bones.
A team of paleontologists and pathologists conducted a study published in The Lancet, researching dinosaur bones thoroughly. Microscopic evidence of bone shape and structure revealed traces of osteosarcoma.
'If humans and dinosaurs get the same kinds of bone cancers,' said paleontologist Catherine Forster from George Washington University, 'then bone cancers developed deep in evolutionary history before the mammal and reptile lineages split 300 million years ago.' This changes the timeline of the history and origins of cancer.
The Centrosaurus Dinosaur
The first traces of bone cancer in one dinosaur bone led to discovering the same cancer in several dozens of Centrosaurus bones, a horned herbivore dinosaur. Researchers assumed that the massive bonebed is the remnants of a herd of Centrosauruses that died due to a flash flood.
In 1989, when the Royal Tyrrell Museum of Paleontology discovered the bones, the fibulas (leg bone) had traces of injury. Scientists speculated that it may have been a healed fracture and were not reassessed until years later.
When paleontologist David Evans met Mark Crowther, a pathology specialist, they ended up talking about dinosaurs and bone cancer. Evans said that perhaps they can 'find dino cancer' at the Royal Tyrrell Museum.
Assessing the fibulas from 1989, musculoskeletal oncologists and pathologists studied the interior structure of the bones with high-resolution X-ray CT scans. The team then confirmed the diagnosis of osteosarcoma, the first time this particular cancer has been linked to dinosaurs.
Advantage of Belonging to a Herd
Upon the new findings, paleopathologist Ewan Wolff from Montana State University wanted 'to see [a] comparison to animals more closely related to dinosaurs.' This would include birds like robins and pelicans that have been found to develop the same bone cancer as well.
The osteosarcoma found in the dinosaur bones appeared to be so advanced that most likely, cancer had spread to other parts of the body. Although the cancer is malignant and aggressive, the survival of ill Centrosauruses revealed the advantages of their social behavior.
Carnivores typically target sick or injured animals yet 'living within a large herd provided safety in numbers and likely allowed it to avoid predation as cancer progressed, allowing it to survive longer with this debilitating cancer than it would have on its own,' explained Evans. Andrew Farke from the Raymond M. Alf Museum of Paleontology said, 'If you are a sick horned dinosaur, being able to blend in with others of your kind will probably buy you some time versus being out solo.'
Evans also said that this discovery makes dinosaurs 'more real' by bringing them to life as scientists discover the injuries and diseases they suffered from. 'Dinosaurs can seem like mythical creatures, but they were living, breathing animals,' he said.
