A rare, ancient case of bone cancer has been found in a turtle ancestor

A 240-million-year-old case of bone cancer has turned up in a fossil of an extinct ancestor of turtles. Dating to the Triassic Period, the fossil is the oldest known example of this cancer in an amniote, a group that includes mammals, birds and reptiles, researchers report online February 7 in JAMA Oncology. 

The fossilized left femur from the shell-less stem-turtle Pappochelys rosinae was recovered in southwestern Germany in 2013. A growth on the leg bone prompted a team of paleontologists and physicians to analyze the fossil with a micro CT scan, an imaging technique that provides a detailed, three-dimensional view inside an object.

“When we saw that this was not a break or an infection, we started looking at other growth-causing diseases,” says Yara Haridy, a paleontologist at the Museum für Naturkunde in Berlin. The verdict? Periosteal osteosarcoma, a malignant bone tumor. “It looks almost exactly like human periosteal osteosarcoma,” Haridy says.

“It is almost obvious that ancient animals would have cancer, but it is so very rare that we find evidence of it,” she says. The discovery of this tumor from the Triassic offers evidence that cancer is “a vulnerability to mutation deeply rooted in our DNA.”