Mighty T. Rex Killed by Pigeon Parasite?

After surviving countless battles, a giant T. rex was ultimately taken down by a microscopic parasite akin to one carried by modern pigeons, scientists say.

The finding is a new interpretation of multiple holes in the jawbone of "Sue," the largest and most complete Tyrannosaurus rex fossil yet found, which is on display at the Field Museum in Chicago.Initially researchers had said the holes are bite wounds made by other another T. rex. But most paleontologists now agree that the holes are too neat and smooth to have been caused by teeth scraping across bone.

In a new study, researchers instead propose that the holes are lesions made by an ancient version of trichomonosis, a single-celled parasite that infects the throats and beaks of modern birds.How the huge dinosaur died, however, has been unclear. Despite Sue's multiple injuries, the animal seems to have lived with most of them for years.In birds, trichomonosis causes inflammation in the beak and upper digestive tract, which makes feeding and even breathing very difficult.Birds' bodies react by sealing off infected tissue, but over time byproducts from this immune response can damage bone, creating lesions.

Sue had about ten such lesions on her jaw, some of them large enough for a human adult to poke a finger through.Based on the size and number of lesions, the team thinks Sue's disease was at an advanced stage and may have been so severe that the dinosaur starved to death.

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