Even mighty prehistoric giants like Tyrannosaurus rex were plagued with parasites, according to Gross Science host Anna Rothschild. In the video below, Rothschild explains how scientists have discovered evidence of several types of creepy critters inside fossilized dinosaur poop, including flatworm and roundworm eggs, and cysts resembling those of present-day amoebas.

Ancient parasites might have afflicted more than just the dinosaurs’ guts, too: For example, scientists have found a biting fly with a malaria-like parasite inside its intestines, preserved in 100 million-year-old amber. This fly may have once fed on dinosaurs, meaning dinos may have suffered from the same infectious disease as humans. Meanwhile, another variety of parasite may have caused T. rex to develop flesh-eating ulcers in their mouths and esophaguses. Some researchers even believe that dinosaurs could have had giant tapeworms snaking their way through their intestines.

As scientists continue to dig up dino poop, they may discover even more pesky organisms inside the prehistoric dung. In the meantime, take consolation in the fact that even the fiercest creatures that likely ever walked the planet weren't above the tiniest indignities of nature.