Sue, the biggest and best-preserved Tyrannosaurus rex ever unearthed, no doubt was a fearsome beast when this predator prowled what is now South Dakota about 67 million years ago at the twilight of the age of dinosaurs.
But even this huge dinosaur, whose fossils are displayed at the Field Museum in Chicago, was not invulnerable. A prime example of this is the series of circular holes in Sue's jawbone that continue to baffle scientists. New research seeking an explanation for these holes has managed to rule out one major hypothesis, though the answer remains elusive.
