Irritator

Irritator; Temporal range: Lower Cretaceous; 110 mya
	Reconstructed skeleton at the National Museum of Nature and Science, Tokyo. The postcranium is based on remains that cannot be confidently attributed to the animal.
Scientific classification
Unrecognized taxon (fix):	Irritator
Species
	I. challengeri Martill et al. 1996 (type);
Synonyms
	Angaturama limai? Kellner & Campos 1996;

Irritator (say: irr-irr-it-at-or) is a genus of spinosaurid theropod dinosaur that lived in what is now Brazil, in the Lower Cretaceous. Its fossils are known from the Romualdo Formation.^[1]

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.^[2] 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.^[3]

Irritator Media

Map showing the Northeast Region of Brazil, with the discovery sites of three spinosaurine fossil specimens in the Araripe and São Luís-Grajaú Basins marked. From top to bottom: Oxalaia, Irritator, and Angaturama
Outdated reconstruction of the holotype skull (top) based on the interpretations of Martill and colleagues in 1996. Depictions (similar to the one at the bottom) based on this reconstruction were later featured in many dinosaur books and encyclopedias.
Known skull elements of Irritator as interpreted by paleontologist Jaime A. Headden; the snout tip is from the Angaturama specimen.
Holotypes of Irritator challengeri and Angaturama limai in place, showing the latter's larger skull size and overlapping third left maxillary tooth, as proposed by Sales and Schultz in 2017
Spinosaurine pelvis and sacral vertebrae (specimen MN 4819-V), National Museum of Rio de Janeiro
Estimated size of Irritator (light green) and Angaturama's (dark green) holotype specimens with a human
Holotype skull of Irritator challengeri from left (top) and right side views
Life restoration of Irritator
Closeup of Irritator's upper jaw and Template:Dinogloss
Holotype of Angaturama limai from various angles

References

↑ Aureliano, Tito. Semi-aquatic adaptations in a spinosaur from the Lower Cretaceous of Brazil. Cretaceous Research 90 (2018-05-03). p. 283–295. doi:10.1016/j.cretres.2018.04.024.
↑ Sues, H. D.. Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology 22 (3) (2002). p. 535–547. doi:[0535:ICASDT2.0.CO;2 10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2].
↑ Martill, D. M.. A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil. Journal of the Geological Society 153 (1) (1996). p. 5–8. doi:10.1144/gsjgs.153.1.0005.

[:42-1] Aureliano, Tito. Semi-aquatic adaptations in a spinosaur from the Lower Cretaceous of Brazil. Cretaceous Research 90 (2018-05-03). p. 283–295. doi:10.1016/j.cretres.2018.04.024.

[:5-2] Sues, H. D.. Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology 22 (3) (2002). p. 535–547. doi:[0535:ICASDT2.0.CO;2 10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2].

[Martill96-3] Martill, D. M.. A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil. Journal of the Geological Society 153 (1) (1996). p. 5–8. doi:10.1144/gsjgs.153.1.0005.

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