Doctor Bruce Rothschild is an expert in ancient diseases. He's studied tuberculosis in mastodons and arthritis in a Tyrannosaurus rex. But even he'd never seen this particular type of tumour in a dinosaur before. No one had.
The small jaw of a young duck-billed dinosaur had a huge, strange growth on one side - a non cancerous facial tumour called a ameloblastoma. Humans get them, as do modern mammals and some reptiles. But they'd never been seen in fossilised form.
"The discovery of an ameloblastoma in a duck-billed dinosaur documents that we have more in common with dinosaurs than previously realised," Rothschild said in a news release.
In a study published this week in the journal Scientific Reports, Rothschild and his colleagues describe the disfigured jaw of an ailing 67-million-year-old dinosaur. It was a Telmatosaurus transsylvanicus - a species of dwarfed hadrosaur that lived in Romania's "Valley of the Dinosaurs" just before the asteroid impact that would bring about the ancient reptiles' demise.
But before that catastrophic impact, dinosaur life was dictated by the same concerns that preoccupy animals today: getting food, not becoming food, avoiding injury and disease. Understanding those last two factors is crucial for "revealing a very particular facet of dinosaurian life and death," the researchers write, because they say a lot about a creature's behaviour. Healed-over wounds might indicate an escape from a predator or a fight with a peer; evidence of chronic disease can illuminate how long a creature lived, and whether its relatives helped it survive.