A detailed analysis of the teeth from Sue, one of the world's most famous T. rex specimens, supports evidence of a severe parasitic infection in her final days. This infection may have ultimately caused her death.
Sue stands as one of the largest and most complete T. rex fossils ever discovered. Unearthed in 1990 on the Cheyenne River Indian Reservation in South Dakota, this theropod—whose sex remains undetermined—measured 12.8 meters long and 3.9 meters high at the hips when alive around 67 million years ago.
The cause of Sue's death remains a topic of debate. Theories range from drowning in a river to starvation due to feeding difficulties caused by a parasitic infection. A 2009 study in PLOS ONE favored the latter, based on examination of her jawbone—now displayed at the Field Museum in Chicago—which shows several holes initially mistaken for battle wounds.
Researchers determined these lesions were caused by a small parasite known as Trichomonas gallinae, which today causes trichomoniasis in birds of prey, leading to severe beak lesions.
In a recent study led by paleontologist Kirstin Brink from the University of Manitoba in Winnipeg, Canada, advanced CT scans and 3D imaging revealed that the infection likely deformed several of Sue's teeth. Three teeth appeared "crushed and bent", with "a weird, almost rippling texture on the sides". Two of these had fused together.
While dental issues were common among theropods, they were typically genetic in origin. The fact that only three teeth were affected—not the entire set—rules out genetics here, linking the damage to the parasitic infection identified in 2009.
Brink notes that modern birds, theropod descendants, develop waxy throat growths from trichomoniasis. "The infection can spread through the skull and skin, affecting many head tissues," she explains. Though modern birds lack teeth, this parallels Sue's pathology.
