Afrovenator
Encyclopedia
Afrovenator is a genus
of megalosaurid
theropod dinosaur
from the mid Jurassic
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 9 metres (30 ft) 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 fossil
s 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 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). 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
.
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
.
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 Afrovenators 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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of megalosaurid
Megalosaurid
Megalosauridae was a family of relatively primitive tetanuran theropod dinosaurs, order Saurischia. They were small-to-large carnivores with sharp teeth and three claws on each hand. Some members of this group were Megalosaurus, Eustreptospondylus, Streptospondylus and Torvosaurus...
theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the mid Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
Period of northern Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. 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 9 metres (30 ft) long from snout to tail tip.
The generic name comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
prefix afro- ("from Africa") venator ("hunter"). There is one named species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, 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
Niger
Niger , officially named the Republic of Niger, is a landlocked country in Western Africa, named after the Niger River. It borders Nigeria and Benin to the south, Burkina Faso and Mali to the west, Algeria and Libya to the north and Chad to the east...
where the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s were found. The original description of both genus and species is found in a 1994 paper which appeared in the prestigious journal Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
. The primary author was well-known American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
paleontologist Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
, with Jeffrey Wilson, Hans Larsson
Hans Larsson
Hans Larsson was a Swedish Professor of Philosophy at Lund University, Sweden and a Member of the Swedish Academy , chair no. 15. He was known in Sweden as Kloke-Hans .Prof. Larsson was a humanist and an author...
, Didier Dutheil, and Hans-Dieter Sues
Hans-Dieter Sues
Hans-Dieter Sues is a German-born paleontologist who is Senior Scientist and Curator of Vertebrate Paleontology at the National Museum of Natural History of the Smithsonian Institution in Washington, DC. He received his education at Johannes Gutenberg-Universität Mainz , University of Alberta, and...
as coauthors.
Discovery
Tiouraren Formation
The Tiouraren Formation is a geological formation in Niger whose strata were originally thought to be Early Cretaceous. However, re-interpretation of the sediments showed that they are probably mid-Jurassic in age. Dinosaur remains are among the fossils that have been recovered from the...
of the department of Agadez
Agadez (department)
Agadez is an administrative Region in Niger. Agadez covers . The capital of the department is Agadez.-Description and people:The Agadez Region represents 52% of the total area of Niger, the largest of its seven regions. Despite its size, Agadez is sparsely populated; its 321,639 inhabitants account...
in Niger. The Tiourarén was originally thought to represent the Hauterivian
Hauterivian
The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous epoch or a stage in the Lower Cretaceous series. It spans the time between 136.4 ± 2 Ma and 130 ± 1.5 Ma...
to Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
stages of the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Period, or approximately 136 to 125 million years ago (Sereno et al. 1994). However, re-interpretation of the sediments showed that they are probably mid-Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
in age, dating Afrovenator to the Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
to Oxfordian stages, between 164 and 161 mya. The sauropod Jobaria
Jobaria
Jobaria was a sauropod dinosaur discovered in the Sahara Desert in 1997. It was named after "Jobar", a creature of local legends, and is thought to have been about 18 metres long. It was found in the Tiourarén Formation, originally thought to represent the Hauterivian to Barremian stages of the...
, whose remains were first mentioned in the same paper which named Afrovenator, is also known from this formation
Geologic formation
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...
.
Afrovenator is known from a single nearly complete skeleton, featuring most of the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
(minus the mandible
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
, or lower jaw), parts of the spinal column, hands, and forelimbs, a nearly complete pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
, and complete hind limbs. This skeleton is housed at the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
.
Taxonomy
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 SpinosauridaeSpinosauridae
Spinosauridae is a family of specialised theropod dinosaurs. Members of this family were large, bipedal predators with elongated, crocodile-like skulls, sporting conical teeth with no or only very tiny serrations. The front dentary teeth fanned out, giving the animal a characteristic look...
within the Megalosauroidea
Megalosauroidea
Megalosauroidea is a group of tetanuran theropod dinosaurs that lived from the Middle Jurassic to the Late Cretaceous period.-Classification:...
.
A 2002 analysis, focused mainly on the noasaurids
Noasauridae
Noasaurids were a group of theropod dinosaurs from the Cretaceous Period . They were generally small in size...
, found Afrovenator to be a basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
megalosaurid. However, it did not include Dubreuillosaurus
Dubreuillosaurus
Dubreuillosaurus is a genus of carnivorous dinosaur from the middle Jurassic Period. It was a megalosaurid theropod. Its fossils were found in France....
(formerly Poekilopleuron
Poekilopleuron
Poekilopleuron is an extinct genus of large basal tetanuran theropod dinosaur, perhaps belonging to the clade Allosauroidea. It measured 9 metres long and 1 ton in mass...
valesdunesis), which could affect the results in that region of the cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
(Carrano et al. 2002).
Other recent, more complete, cladistic analyses show Afrovenator in a subfamily of Megalosauridae with Eustreptospondylus
Eustreptospondylus
Eustreptospondylus is a genus of megalosaurid dinosaur, from the Callovian stage of the Middle Jurassic period in southern England, at a time when Europe was a series of scattered islands Eustreptospondylus ("well-curved vertebra", in reference to the arrangement of the spine in the original...
and Dubreuillosaurus. This subfamily is either called Megalosaurinae (Allain 2002) or Eustreptospondylinae (Holtz et al. 2004). The latter study also includes Piatnitzkysaurus
Piatnitzkysaurus
Piatnitzkysaurus is a genus of theropod dinosaur. It is known from the Canadon Asfalto Formation, Middle Jurassic of what is now Argentina. Once thought to be a basal carnosaur, it may instead be a megalosauroid...
in this subfamily.
A few alternative hypotheses have been presented for Afrovenators 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
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...
(Rauhut 2003). This is the only study to draw this conclusion.