A cluster of ancient tapeworm eggs was discovered in 270-million-year-old fossilized shark feces, indicating that intestinal parasites in vertebrates are older than previously thought.

Flattened like a tape, tape worms are intestinal parasites that cannot live on their own. It clings within the gut of animals, including humans. It enters the host through ingested food. It releases its egg through the feces of the host. It is very rare to find the remains of such parasites in vertebrates from the period of the dinosaurs.