Afrovenator ("African hunter") is an extinct genus of megalosaurid theropod dinosaur from the Early Cretaceous Period of west Africa.
.jpg){kind=link}
Afrovenator skeleton
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.
Description[]
Size of Afrovenator (in orange) compared to two other afrovenatorines
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, and to have weighed up to 1 tonne. Sereno stressed that the general build was gracile and that the forelimbs and legs were relatively long. The humerus, having a length of 400 millimetres, and the tibia and fourth metatarsal measure 687 and 321 millimetres respectively, compared with a thigh bone length of 760 millimetres.
Several autapomorphies have been established, the traits that distinguish Afrovenator from its closest relatives. The depression in which the antorbital fenestra is located has a lobe-shaped front end. The third neck vertebra has a low rectangular spine. The semiulunate wrist bone is very flat. The first metacarpal has a wide contact surface with the second metacarpal. The pubic peduncle is notched from behind.
The skull is generally rather flat, its height being less than three times its length, which cannot be determined exactly because the premaxilla is missing. The maxilla, which has a long anterior ramus, bears fourteen teeth, as can be deduced from the dental alveoli, the teeth themselves having been lost. There is a small maxillary fenestra, which does not reach the edge of the antorbital depression and is situated behind a promaxillary fenestra. The lacrimal bone has a distinctive rounded horn on top. The inferior ramus of the postorbital medulla is transversely broad. The malar bone is short and deep and pneumatized.
However, re-interpretation of the sediments showed that they are probably mid-Jurassic in age, dating Afrovenator to the Bathonian to Oxfordian stages, between 164 and 161 mya. The sauropod Jobaria, whose remains were first mentioned in the same paper which named Afrovenator, is also known from this formation.
Discovery[]
Skeletal diagram of known material
The remains of Afrovenator were discovered in 1993 in the Tiouraren Formation of the department of Agadez in Niger. The Tiouraren was originally thought to represent the Hauterivian to Barremian stages of the early Cretaceous period, or approximately 132 to 125 million years ago. However, re-interpretation of the sediments showed that they are probably Mid-Jurasic in age, dating Afrovenator to the Bathonian to Oxfordian stages, between 167 and 161 mya. 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 relatively complete skeleton, holotype UC OBA 1, featuring most of the skull minus its top (likewise the mandible, or lower jaws, are lacking apart from the prearticular bone), parts of the spinal column, partial forelimbs, a partial pelvis, and parts of the hind limbs. This skeleton is housed at the University of Chicago.
The remains of Afrovenator were discovered in the Tiourarén Formation of the department of Agadez in Niger. The Tiourarén was originally thought to represent the Hauterivian to Barremian stages of the early Cretaceous Period, or approximately 136 to 125 million years ago (Sereno et al. 1994). It was dated to the Hauterivian and Barremian strata by Sereno, approximately 136 to 125 million years ago, but was later considered by Rauhut and Lopez-Arbarello to be from the Middle Jurassic between the Bathonian and Oxfordian eras, approximately 164 to 161 million years ago. Afrovenator is known from a partial skeleton, holotype UC OBA 1 , which includes much of the skull, the lower jaw is missing, part of the vertebral column, claws, forelimbs and hindlimbs, and most of the pelvis. The skeleton is housed at the University of Chicago. The generic name is derived from the Latin words afro- ("Africa") and venator ("hunter"). With only one named species, A. abakensis . The name refers to its predatory nature, and to its location in Africa, specifically in In Abaka, the Tuareg name for the region in Niger where the fossil was found. The original description of both genus and species was made in 1994 and appeared in the prestigious journal Science . The primary author was the American paleontologist Paul Sereno, with Jeffrey Wilson, Hans Larsson, Didier Dutheil and Hans-Dieter Sues as co-authors.
Taxonomy[]
Life restoration
Most 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 Megalosauroidea.
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 Megalosauroidea completely, and instead finds it more closely related to Allosaurus (Rauhut 2003). This is the only study to draw this conclusion.
| Avetheropoda |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
JPInstitute.com Description[]
Afrovenator was the first almost complete skeleton found of a large African meat-eating dinosaur. It was unearthed in 1993 by an amateur fossil hunter who was on a National Geographic-sponsored expedition. This dinosaur was medium-sized and built for a life of active hunting, with long, strong back legs and large, strong arms designed for catching and holding its prey.
Afrovenator appears to be descended from earlier dinosaurs such as Megalosaurus. As this family was widely spread through ancient Europe and possibly South America, it is not surprising that a relation would also have lived in Africa as its ancestors may have passed through. The only major Afrovenator parts missing from the type specimen are most of the lower jaw, the nose, some ribs and vertebrae, and toe bones. All in all, it is a remarkably complete specimen.