Even mighty dinosaurs such as Tyrannosaurus rex were not immune from being pestered by parasites, as this video from PBS’s Gross Science explains.
By examining fossilised dinosaur droppings – known as coprolites – palaeontologists have found evidence of internal parasites including eggs from flatworms and roundworms, and cysts that look like those formed by modern amoebas. A 100-million-year-old fly has also been found preserved in amber that hosted a malaria-like parasite in its own guts, indicating that dinosaurs too may have been prey to the tiny infectious organism. Distinctive holes in T. rex jawbones may also be signs of a parasite that caused invasive ulcers in the mouth and throat.
It just goes to show that strength and size are no defence against parasites. For that, you need hygiene and – if all else fails – modern medicine.