The diagnosis? Osteosarcoma – an aggressive bone cancer – in the fibula, or the bone of the leg, of a Torosaure, a herbivorous single-horned dinosaur that lived 76 to 77 million years ago.
The discovery opens up new understanding of other diseases that may have developed in dinosaurs, among other aspects of dinosaur life.
“What this study shows, because we found bone cancer at a fairly advanced stage, is that dinosaurs weren’t just suffering from bone cancer, but probably all kinds of other cancers that we do. let’s see in invertebrates today, ”says David Evans, a paleontologist at the Royal Ontario Museum and one of the study’s principal investigators.
Although the diagnosis is new, the bone was discovered in 1989. It was at this time that a crew from the Royal Tyrrell Museum in Drumheller, Canada discovered the fibula in a massive bone bed in Alberta, Canada. .
The fibula was severely deformed, but scientists initially assessed it as a broken bone on the mend and the odd shape was a callused fracture.
The bone was part of the museum’s collection until 2017, when a team led by Evans and Mark Crowther, professor of pathology at McMaster University, began excavating the hundreds of injured or partially healed bones during of a mission.
“We went looking for dinosaur cancer,” says Evans.
Evans, Crowther, and Snezana Popovic, an osteopathologist at McMasters, combed through hundreds of bones before they found the unusually malformed fibula to look for signs of cancer.
They called in specialists in various fields, including pathology, radiology, orthopedic surgery and paleopathology, to examine and diagnose the suspected tumor.
« The approach we took in this case was very similar to how we approach a patient who comes with a new tumor, and we don’t know what type of tumor it is, ”says Seper Ekhtiari, a resident in orthopedic surgery at McMaster University who worked on the team.
They were able to visualize cancer progression through bone by performing high-resolution CT scans of the fibula and examining thin sections of bone at the cellular level under a microscope.
The team confirmed the diagnosis of osteosarcoma by comparing the fibula bone of a healthy centrosaurus and that of a human with osteosarcoma.
Although this is the first identified case of osteosarcoma in a dinosaur, Ekhtiari says it makes sense that cancer associated with rapid bone growth has struck dinosaurs.
“One of the ways they’ve come to such massive sizes is that they’ve grown extremely quickly from birth,” says Ekhtiari. “So finding that in a dinosaur isn’t surprising. In fact, he says, bone cancer “is probably more common than we think, or more common than what we have found so far.”
Crowther, the pathologist, adds that their discovery suggests that the dinosaurs likely suffered from other diseases that affect the bones – such as tuberculosis and osteomyelitis.
While this points to a potential cause of death for dinosaurs, the cancer discovery also provided insight into how they lived and survived.
Take the sick centrosaurus. While he was reportedly severely hampered by the advanced stage of cancer found in his fibula, he did not die of the disease, nor was he removed by a predator such as a Tyrannosaurus rex. His bones were found in a bone mass, which scientists believe to be the partial remains of a large herd drowned by a flood.
“The cancer may have progressed to the stage it did because of the safety of the number of the herd in which it lived,” says Evans, the paleontologist.
While the discovery opens many new doors in paleontology and pathology, one of the study’s biggest impacts could be a change in the way we think about dinosaurs.
“We often think of dinosaurs as some sort of mythical and powerful creature, and I think this finding really underscores that they can be plagued by the diseases we see around us today, even horrific deadly cancers,” Evans says. “I think in a weird way it brings them back to life even more. “