Jeffrey Wilson

Afrovenator

Afrovenator ("African hunter") is a genus of megalosaurid theropod dinosaur from the Early Cretaceous Period of northern Africa. It was a bipedal predator, with a mouthful of sharp teeth and three claws on each hand. Judging from the one skeleton known, this dinosaur was approximately 30 feet (9 meters) long from snout to tail tip.

The generic name comes from the Latin prefix afro- ("from Africa") venator ("hunter"). There is one named species, A. abakensis. The name refers to its predatory nature, and its location in Africa, specifically from In Abaka, the Tuareg name for the region of Niger where the fossils were found. The original description of both genus and species is found in a 1994 paper which appeared in the prestigious journal Science. The primary author was well-known American paleontologist Paul Sereno, with Jeffrey Wilson, Hans Larsson, Didier Dutheil, and Hans-Dieter Sues as coauthors.

The remains of Afrovenator were discovered in the Tiourarén Formation of the department of Agadez in Niger. The Tiourarén most likely represents the Hauterivian to Barremian stages of the Early Cretaceous Period, or approximately 136 to 125 million years ago (Sereno et al. 1994). The sauropod Jobaria, whose remains were first mentioned in the same paper which named Afrovenator, is also known from this formation.

Afrovenator is known from a single nearly complete skeleton, featuring most of the skull (minus the mandible, or lower jaw), parts of the spinal column, hands, and forelimbs, a nearly complete pelvis, and complete hind limbs. This skeleton is housed at the University of Chicago.

Taxonomy

Most modern analyses place Afrovenator within Megalosauridae, which was formerly a "wastebasket family" which contained many large and hard-to-classify theropods, but has since been redefined in a meaningful way, as a sister taxon to the family Spinosauridae within the Spinosauroidea.

A 2002 analysis, focused mainly on the noasaurids, found Afrovenator to be a basal megalosaurid. However, it did not include Dubreuillosaurus (formerly Poekilopleuron valesdunesis), which could affect the results in that region of the cladogram (Carrano et al. 2002).

Other recent, more complete, cladistic analyses show Afrovenator in a subfamily of Megalosauridae with Eustreptospondylus and Dubreuillosaurus. This subfamily is either called Megalosaurinae (Allain 2002) or Eustreptospondylinae (Holtz et al. 2004). The latter study also includes Piatnitzkysaurus in this subfamily.

A few alternative hypotheses have been presented for Afrovenator's relationships.

In Sereno's original description, Afrovenator was found to be a basal spinosauroid (he uses the name "Torvosauroidea"), outside of Spinosauridae and Megalosauridae (which he calls "Torvosauridae") (Sereno et al. 1994).

Finally, another recent study places Afrovenator outside of Spinosauroidea completely, and instead finds it more closely related to Allosaurus (Rauhut 2003). This is the only study to draw this conclusion.

References

  • Allain, R. 2002. Discovery of megalosaur (Dinosauria, Theropoda) in the middle Bathonian of Normandy (France) and its implications for the phylogeny of basal Tetanurae. Journal of Vertebrate Paleontology 22(3): 548-563.
  • Carrano, M.T., Sampson, S.D. & Forster, C.F. 2002. The osteology of Masiakasaurus knopfleri, a small abelisauroid (Dinosauria: Theropoda) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 22(3): 510-534.
  • Holtz, T.R., Molnar, R.E., Currie, P.J. 2004. Basal Tetanurae. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 71-110.
  • Rauhut, O.W.M. (2003). The Interrelationships and Evolution of Basal Theropod Dinosaurs. Special Papers in Palaeontology 69. London: The Palaeontological Association. Pp. 1-215.
  • Sereno, P.C., Wilson, J.A., Larsson, H.C.E., Dutheil, D.B., & Sues, H-D. 1994. Early Cretaceous dinosaurs from the Sahara. Science 266: 267-270.

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