A team of researchers have revealed that holes commonly found in the jaws of Tyrannosaurs may be due to a protozoan infection. Many of these holes have previously been attributed to wounds inflicted by other Tyrannosaurs or struggles with their prey.
The hypothesized protozoan is a species of Trichomonas, possibly Trichomonas gallinae. T. gallinae is found in modern pigeon species as well as birds-of-prey that prey upon infected pigeons. Infections result in lesions on the jaws and interior of the mouth of infected birds. Infections can be severe enough to potentially prevent feeding by birds, which can result in the starvation of infected birds. Infections in birds-of-prey are also accompanied by holes in the mandible, which are similar to the holes found in a number of T. rex specimens including 'Sue' at the Chicago Field Museum.