After seven years of investigation, an international team of researchers released an article Tuesday confirming the world famous Tyrannosaurus rex, commonly known as Sue, on display at the Field Museum of Chicago died due to a parasite infection instead of a violent encounter, as was previously believed.
In “Common Avian Infection Plagued the Tyrant Dinosaurs,” published by Public Library of Science One, lead author Ewan Wolff, a third-year graduate student at UW’s veterinary school, took the next step in developing the connection between modern birds and dinosaurs by comparing the trichomoniasis infection of Sue to modern birds.
The study helps paleontologists better understand the T. rex immune system to show a modern form of avian disease is present in prehistoric T. rexes, according to Wolff.
Although common beliefs hold the holes found in Sue’s jaws are bite marks from confrontations with other dinosaurs, Wolff’s research proves otherwise.
“We can infer that because of the severity of infection, she succumbed to starvation because of the buildup of chronic inflammatory debris in the back of the throat,” Wolff said. “This inflammation of tissue and production of a cheesy debris in her throat occurred as a result of the avian immune response to the disease.”
Instead of dying valiantly in a battle against fellow enormous beasts, Sue the T. rex died as a result of an ordinary parasite infection, Wolff said.
“This individual is actually already a respected vertebrate paleontologist, it’s always exciting when students do interesting and provacotive thing, so it’s a great thing. It’s very exciting and an interesting puzzle,” UW spokesperson Terry Devitt said. “I don’t think anyone was sure of how Sue died — it’s always interesting when there is a new and exciting hypothesis.”
According to the team’s research article, the cause of the holes in Sue’s jaws had previously been attributed to actinomycosis, a bacterial bone infection, or bite wounds from other tyrannosaurids.
Wolff said he and his colleagues first suspected trichamoniasis as a cause of death after studying a T. rex with similar holes in its jaw in 2002.
Upon further research, the team developed a concrete link between this T. rex’s disease and an identical cause of death among modern birds and crocodiles.
“Unfortunately, the reason why Sue died from the disease is that, while trying to localize the disease, swollen tissues and a cottage cheese-like inflammatory debris [were] building up in the back of her throat which [made] it more and more difficult to feed,” Wolff said.
Wolff was able to determine this by researching jawbone holes and comparing them to the skulls of modern birds that suffered from the same disease.
“We found holes inside the jaws of not only Sue, but also nine other Tyrannosauruses,” Wolff said.
Wolff’s research team found identical, symmetrical holes in the jawbones of 10 out of the 65 of the T. rexes studied, all depicting evidence of similar trichomoniasis disease. Therefore, the researchers believe it was a fairly common cause of death for T. rexes.