# Irritator challengeri

> A spinosaurid from the Early Cretaceous of north-east Brazil, known from the most complete spinosaurid skull ever found. Its long, narrow snout and conical teeth suited catching fish and other small prey on a tropical coastal lagoon.

- Classification: Dinosauria (clade) > Saurischia (clade) > Theropoda (clade) > Tetanurae (clade) > Megalosauroidea (superfamily) > Spinosauridae (family) > Spinosaurinae (subfamily) > Irritator (genus) > Irritator challengeri (species)
- Length: 6–8 m
- Hip height: 1.8–2.4 m
- Mass: 1 t
- Age: 119.6–113.2 million years ago (Early Cretaceous)
- Fossils found in: Romualdo Formation (Ceará); Brazil
- Diet: piscivore, carnivore
- Described: David M. Martill et al., 1996

Canonical page: https://dinodex.club/dinosaurs/irritator-challengeri
Last updated: 2026-09-27

## Overview

Irritator challengeri lived in the Araripe Basin of north-east Brazil in the late Aptian, a little over 113 million years ago. Its skull came out of a limestone concretion near Santana do Cariri, Ceará, and was sold by fossil dealers to the State Museum of Natural History in Stuttgart, Germany.

Dealers had built up the snout with plaster to make it look longer, which "irritated" the researchers who had to remove it; the species name honours Professor Challenger of Arthur Conan Doyle's "The Lost World". Martill and colleagues (1996) first thought it was a maniraptoran, and Sues and colleagues (2002) showed it was a spinosaurid.

CT scans by Schade and colleagues (2023) revealed almost the whole palate and braincase. The skull had binocular vision in front of the snout and a relatively weak but fast bite, and the lower jaws spread sideways when opening, like those of pelicans. It probably snapped up fish and small vertebrates, and a spinosaurid tooth has even been found in a pterosaur neck bone from the same rocks.

## Name meaning

From "irritation", for the frustration caused by the dealers' alterations to the skull; challengeri after Professor Challenger in Conan Doyle's "The Lost World" (Martill et al. 1996).

## Sources

1. (2026). Paleobiology Database: Irritator challengeri occurrence and type collection 28052. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/colls/list.json?coll_id=28052&show=paleoloc,strat,loc,ref,geo&pgm=gplates&vocab=pbdb
2. (2026). Wikipedia: Irritator. Wikipedia (English), accessed 2026-09-24. https://en.wikipedia.org/wiki/Irritator
3. Martill, D. M., Cruickshank, A. R. I., Frey, E., Small, P. G. & Clarke, M. (1996). A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil. Journal of the Geological Society 153: 5-8. https://doi.org/10.1144/gsjgs.153.1.0005
4. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.
5. Schade, M., Rauhut, O. W. M. & Evers, S. W. (2020). Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory. Scientific Reports 10: 9259. https://doi.org/10.1038/s41598-020-66261-w
6. Schade, M., Rauhut, O. W. M., Foth, C., Moleman, O. & Evers, S. W. (2023). A reappraisal of the cranial and mandibular osteology of the spinosaurid Irritator challengeri (Dinosauria: Theropoda). Palaeontologia Electronica 26(2): a17. https://doi.org/10.26879/1242
7. Sues, H.-D., Frey, E., Martill, D. M. & Scott, D. M. (2002). Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology 22: 535-547. https://doi.org/10.1671/0272-4634(2002)022[0535:ICASDT]2.0.CO;2

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Cite as: "Irritator challengeri". DinoDex. https://dinodex.club/dinosaurs/irritator-challengeri (updated 2026-09-27).