A new Psittacosaurus (Dinosauria: Ceratopsia) specimen from the Yixian Formation of western Liaoning, China: the first pathological psittacosaurid

A psittacosaurid dinosaur from western Liaoning, China, possessing a pathological fibula is described. The pathological fibula is significantly different from a normal fibula, being shorter and much stouter, and with a distinct swelling on the shaft. The swollen portion (representing a mass of necrotic bone) of the fibula indicates that the animal survived for a relatively long time after becoming diseased, implying that the injuries to the fibula were not fatal, as has also been noted for some theropod dinosaurs. The pathological fibula may have been caused by the tubercle bacillus.