Mystery Killer, Part II
Mike Keesey  

An Irritating Challenge

January 24th, 2006 by Mike Keesey :: 2 Comments

What better to use as Carney’s accuser than an Irritator challegeri?

Of course, the real Irritator challengeri wasn’t particularly irritating or challenging, at least as far as we know. The trivial epithet is named after a fictional A. Conan Doyle character. In The Lost World and other books, Professor Challenger is a scientist on the quest for prehistoric animals in Brazil, which is also I. challengeri’s homeland.

The genus, on the other hand, is named for the irritating condition which the type (and only) specimen was in. Fossil collectors had exaggerated the specimen, a skull, with plaster such that it was difficult to tell the real parts from the fake. Originally thought to be a maniraptoran coelurosaur (Martill et al. 1996), subsequent research by Sues et al. (2002) showed it to be a spinosaurid, a smaller relative of the largest known theropod, Spinosaurus aegyptiacus, recently estimated at 16–18m (dal Sasso et al. 2006). Sues et al. also showed that there is no crest, as originally thought.

Interestingly, the I. challengeri skull is missing the rostralmost portions, and the only other Santana Formation spinosaurid, Angaturama limai Kellner and Campos 1996, is known only from the rostralmost tips of a single animal’s jaws. The two species might not only be synonyms; they might be based on the same animal! Unfortunately it’s impossible to know for certain, but hopefully further material will help clear this up someday.

The name Irritator may reflect a generally growing lassitude in naming dinosaurs. Quilmesaurus Coria 2001 is named after the favorite beer of the paleontologists who found it, Masiakasaurus knopfleri Sampson et al. 2001 is named after a rock musician (Mark Knopfler of Dire Straits) whom the discoveres listened to, and Gojirasaurus Carpenter 1997 is named after everybody’s favorite Tokyo-stomping, radioactive-fire-spewing monster. For more names like this, check out Mark Isaak’s Curiosities of Biological Nomenclature.

Irritator is one of my favorite dinosaur names. I think it’s hilarious. Others, though, find it … irritating.



  • Carpenter, K. 1997. A giant coelophysoid (Ceratosauria) theropd from the Upper Cretaceous of New Mexico, U.S.A. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 205(2):189–208.
  • Coria, R. A. 2001 July. New theropod from the Late Cretaceous of Patagonia. In Tanke, D. H. and Carpenter, K. (eds.) Mesozoic Vertebrate Life: New Research Inspired by the Paleontology of Philip J. Currie. Indiana University Press. 542 pp.
  • dal Sasso, C., S. Maganuco, E. Buffetaut and M. A. Mendez. 2006 January. New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities. J. Vert. Paleo. 25(4):888–896.
  • Doyle, A. C. 1912. The Lost World. Republished 1999 September 1. North Books. 220pp.
  • Isaak, M. [date unknown]. Curosities of biological nomenclature. Online at
  • Kellner, A. W. K. and D. de A. Campos. 1996. First Early Cretaceous theropod dinosaur from Brazil with comments on Spinosauridae. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 199(2):151–166.
  • Martill, D. M., A. R. I. Cruickshank, E. Frey, P. G. Small, and M. Clarke. 1996 January. A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil. J. Geol. Society, London 153:5–8.
  • Sampson, S. D., M. T. Carrano, and C. A. Forster. 2001 January. A bizarre predatory dinosaur from the Late Cretaceous of Madagascar. Nature 409:504–506.
  • Sues, H.-D., E. Frey, D. M. Martill, and D. M. Scott. 2002 September. Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. J. Vert. Paleo. 22(3):535–547.

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