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Irritator facts for kids

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Temporal range: Lower Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Spinosauridae
Genus: Irritator
Martill et al., 1996
Species: I. challengeri
Martill et al., 1996 (type)

Irritator is a genus of theropod dinosaur which was discovered in the Lower Cretaceous of the Santana Formation.

The first identifiable dinosaur from Brazil and the first non-avian from South America, Irritator has teeth similar to Spinosaurus. It has a slender jaw with nostrils well back from the front of the snout (all consistent with fish eating). It also had a large crest on the quadrate bone on top of the skull. It was named due to the feelings of the scientists who described it when they found that the snout had been artificially lengthened to resemble a plesiosaur.

Current estimations indicate a length of 8 meters (26 feet). In 2010, Gregory S. Paul gave lower estimations of 7.5 metres and one tonne. It was found in Brazil. Irritator was a theropod with an unusually shaped crest at the rear of its head, and most likely consumed fish.

So far the only fossil that has been found was an 80 centimeter long fossil skull in the Romualdo Member, a layer member of the Santana Formation. This skull strongly resembles the skulls of Suchomimus and Spinosaurus. The genus is often regarded today as identical (synonymous) with Angaturama, which lived in the same time and the same place as Irritator. 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 well-known spinosaurid in the formation.

Irritator probably nourished itself on fish, like the pterosaurs found in large number in the Santana Formation. Irritator was probably, like today's crocodiles, a food generalist, eating all other animals that it could catch besides 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.

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