What caused holes in Sue the T. rex's jawbone? Scientists are stumped - Reuters

A prime example of this is the series of circular holes in Sue's jawbone that continue to baffle scientists.

Researchers said a close examination of the eight holes - some the diameter of a golf ball - on the back half of Sue's left lower jawbone, or mandible, determined that they were not caused by a type of microbial infection as some experts had proposed.

The holes were found to differ from bone damage caused by such an infection, said Bruce Rothschild, a medical doctor and research associate at the Carnegie Museum of Natural History in Pittsburgh, lead author of the study published this week in the journal Cretaceous Research.

rex specimens have holes similar to Sue's.

The researchers explored whether the holes had been caused by an infection involving microbes called protozoans.

O'Connor noted that one falcon diagnosed with trichomoniasis had shown damage in its jaw, but it differed from Sue's holes.

The bone around Sue's holes showed signs of healing, indicating that whatever caused them did not kill the animal.

Similarities were observed between Sue's healing and the healed breaks in other fossilized bones as well as healing bone seen around holes made in the skulls of ancient Inca people in Peru.

rex individuals, that caused large holes to open up in the jawbone but only in the back of the jawbone, but didn't kill the T.

The holes were not the only examples of damage endured by Sue, a dinosaur that lived about 33 years.