Science news

Another reason dinosaurs are gone

What do Tyrannosaurus rex and today's pigeons have in common? According to a new study by a group of paleontologists, round holes in the jawbones of many T. rex skeletons suggest that the ferocious creatures may have been afflicted by a potentially life-threatening infectious disease, trichomonosis, that occurs today in pigeons and other birds.

Pigeons carry trichomonosis without getting sick, but birds of prey can become infected when they kill and then eat infected pigeons. They can then pass the disease on to their offspring through beak-to-beak contact. The T. rex-bird link is not surprising given the evolutionary relationship between the two.

According to the paleontologists, writing in the scientific journal PLoS One, trichomonosis can cause a chronic throat infection that festers in spots and leads to lesions or holes in birds' jawbones. Several of the most famous T. rex specimens, including "Sue" at the Field Museum in Chicago, have such holes in their lower jaws. In the past these holes were thought to be bite marks caused by fights with other dinosaurs. But, said University of Wisconsin paleontologist Ewan Wolff, lead author of the report, the holes in Sue's jawbone are not shaped like teeth. "They are perfectly round. What they're not, is teeth-shaped," he said. They also occur in exactly the same place as in modern birds with trichomonosis, Wolff said.

Trichomonosis can be fatal when the infection clogs the throat with a cottage-cheese-like debris that makes it impossible to breathe or swallow. Wolff said that based on this new evidence, it is likely that Sue, who had 10 holes in her jaw, "died for an inability to feed properly"; in lay language, she starved.

-- Margaret Shapiro