NOT all dinosaurs roamed the world: one may have hobbled. Caudipteryx, a dino-bird that lived 130 million years ago, was prone to osteoarthritis – perhaps the oldest such diagnosis on record.

Some modern birds are prone to osteoarthritis, the degeneration of bone and cartilage in joints. Curious about when the condition first appeared, Bruce Rothschild at the University of Kansas in Lawrence and colleagues examined the fossilised ankle bones of ancient birds and feathered dinosaurs held in Chinese museums. Three of the 10 available fossils of Caudipteryx showed signs of osteoarthritis (Cretaceous Research, DOI: 10.1016/j.cretres.2011.12.008).

Why Caudipteryx, which was the size of a peacock, should have been prone to the condition is a mystery: osteoarthritis is most common in smaller birds today, says Rothschild.