Irritator Characteristics

Irritator measured 26 feet (8 metres) in length and 9 feet (3 metres) in height. It weighed around 1 ton. All Spinosaurids had very narrow jaws with relatively pointed teeth. The nostrils of Irritator were shifted far to the rear of the skull, and the secondary palate make respiration possible even if the majority of the jaw was under water or held prey. The Irritator had spines along its back.

Irritator was a carnivorous dinosaur and probably fed up on fish. A tooth belonging to Irritator still inserted into a fossil neck vertebral column of a pterosaur, indicates that Irritator ate pterosaurs as well, although it is not known if it actively hunted these animals, or simply scavenged the remains. Irritator was probably, like todays crocodiles, a food generalist, eating all other animals that it could catch besides fish.

It is known from a nearly complete skull which measured 80 centimetres in length and was found in Brazil in a layer member of the Brazilian Santana formation.

The people who found the snout-less skull added plaster to it in order to make it look it more impressive. This nonsense did not fool the paleontologists, but it did irritate them, hence the name.

The skull was recovered nearly complete and is considered the most complete head find of a Spinosaurid. The teeth exhibit a single embedding of the strongly extended and straight teeth with conical tooth crowns, which indicates a continual tooth change, as new teeth were pushed up between the old ones. The teeth exhibit lengths from 6 to approximately 40 millimetres. In the year 2004 parts of a spinal column were discovered in the Santana Formation. These have been assigned, due to their structure, to the Spinosauridae. With very high probability these fossils belong to Irritator, since this is the so far the only so far well-known Spinosaurid of the formation.

Irritator was first scientifically described in 1996 by paleontologists Martill, Cruikshank, Frey, Small and Clarke.