Irritator (say: "irr-irr-it-at-or") is a genus of spinosaurid theropod dinosaur that lived in what is now Brazil during the Lower Cretaceous. Its fossils are known from the Romualdo Formation. "Irritator" had straight and cone-shaped teeth. Its jaws were low, long and slender, with the nostrils placed well back from the front of the snout (all consistent with fish eating). "Irritator" also had a narrow crest made of nasal bones on top of the skull. "Irritator"'s name comes from the English word "Irritation". It was given its name due to the feelings of the scientists who described it when they found that fossil dealers had added plaster to the front of the snout.