Certainly the patient never knew where the hip pain came from, or why its left leg stopped working. The diagnosis arrived only 240 million years later, when a femur turned up in an ancient lake bed in Germany, one side marred by a malignant bone tumor.

Cancer seldom appears in the fossil record, and its history among vertebrates is poorly understood. On Thursday, a team of researchers writing in JAMA Oncologyhave described the femur as the oldest known case of cancer in an amniote, the group that includes reptiles, birds and mammals.

Modern cancers are often diagnosed through soft-tissue examinations or biopsies, but that is a difficult prospect for cancer-hunters working with cold, hard fossils. Instead, it takes luck.

“When it comes to our understanding of cancer in the past, we’re really just at the beginning,” said Michaela Binder, a bioarchaeologist at the Austrian Archaeological Institute who’s researched cancer in ancient humans. “It’s not like people say, ‘Oh, I want to go study cancer in ancient turtles or in fossil mammoths,’ because we have so little evidence.”