When the fossil of an ancient turtle relative was collected in Germany in 2013, experts noticed something strange about its left femur. The upper portion of the bone was covered in an obvious, bumpy growth, and researchers puzzled over what might have caused the abnormality. Was it a break that didn’t heal properly? A congenital defect? A disease that impacted the bone? Now, as Asher Elbein reports for the New York Times, a team of scientists has released a paper describing the results of their investigation into the reptile’s remains. The femur growth, they say, was a rare type of cancer that affects humans today.
The femur belonged to a member of the species Pappochelys rosinae, a 240-million-year-old reptile that, in spite of its lack of shell, is believed to be an early ancestor of modern turtles. According to the new study, published in JAMA Oncology, the specimen was found in southwestern Germany and was subsequently transferred to the Stuttgart State Museum of Natural History.
When Yara Haridy, lead author of the study and a paleontologist at Berlin’s Natural History Museum, first encountered the anomalous femur, she thought it had broken and healed incorrectly. But when Haridy and Patrick Asbach, a radiologist at the Charité University of Medicine in Berlin, examined the bone using micro-CT scans, they could see that it was not broken underneath the growth. Other possibilities were also ruled out: a congenital abnormality likely would not present on only one side of the bone, while disease or infection would have worn the femur away, rather than causing a growth.
Ultimately, the researchers concluded that the growth was a malignant tumor, specifically a type of bone cancer called periosteal osteosarcoma. Today, the disease is relatively rare among human patients; between 800 and 900 cases are reported annually in the United States. But Haridy, Asbach and their colleagues were able to identify the proto-turtle’s tumor because it “looks almost exactly like osteosarcoma in humans,” Asbach tells National Geographic’s John Pickrell.
The tumor likely made life difficult for the poor Pappochelys rosinae. It would have had hip pain, Elbein reports, and its left leg may have ceased to function properly. But for modern-day scientists, the find is an exciting one. Because cancer typically affects soft tissues, which are not preserved across millennia, the disease appears very rarely in the fossil record. Some experts have therefore questioned whether cancer was prevalent among the animals that roamed the Earth millions of years ago—or whether it occurred at all.
New insights into the Pappochelys rosinae’s afflicted femur add to a handful of discoveries that suggest prehistoric creatures did indeed get cancer. In 2003, for instance, researchers found 29 tumors in the bones of hadrosaurs, a type of “duck-billed” dinosaur. Another study identified a possible osteosarcoma in the cranial bone of a Triassic amphibian According to the authors of the new research, the Pappochelys rosinae tumor is the earliest-known example of bone cancer in an amniote—an animal group that includes reptiles, mammals and birds.
Also significant is the fact that the reptile’s malignant tumor looked very much like the periosteal osteosarcomas seen in humans today. “We are one community which responds to the environment and whatever factors that cause cancer in the same way,” Bruce Rothschild, study co-author and a research associate at the Carnegie Museum of Natural History in Pittsburgh, tells Live Science’s Yasemin Saplakoglu. “We're all part of the same Earth and we are all inflicted with the same phenomena.”