''Elrhazosaurus'' (meaning " Elrhaz lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of basal

iguanodontia Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', ''Dryosaurus'', ''Iguanodon'', '' Tenontosaurus'', and the hadrosaurids or "duck-bil ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

, known from isolated bones found in Early Cretaceous rocks of

Niger ) , official_languages = , languages_type = National languagesdryosaurid ''

Valdosaurus ''Valdosaurus'' ("Weald Lizard") is a genus of bipedal herbivorous iguanodont ornithopod dinosaur found on the Isle of Wight and elsewhere in England, Spain and possibly also Romania. It lived during the Early Cretaceous. Discovery and naming ...

'', but have since been reclassified.

Discovery and history

''Elrhazosaurus'' is based on MNHN GDF 332, a left

thigh bone The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

collected by

Philippe Taquet Philippe Taquet (b. April 25, 1940 Saint-Quentin, Aisne) is a French paleontologist who specializes in dinosaur systematics of finds primarily in northern Africa. He is a member of the French Academy of Sciences since November 30, 2004, president ...

from the upper part of the

Elrhaz Formation The Elrhaz Formation is a geological formation in Niger, central Africa. Its strata date back to the Early Cretaceous, about 125 to 112 million years ago. Dinosaur remains are among the fossils that have been recovered from the formation, alongsi ...

Gadoufaoua The Elrhaz Formation is a geological formation in Niger, central Africa. Its strata date back to the Early Cretaceous, about 125 to 112 million years ago. Dinosaur remains are among the fossils that have been recovered from the formation, alongsi ...

in the

Ténéré Desert The Ténéré (Tuareg: Tenere, literally: "desert") is a desert region in the south central Sahara. It comprises a vast plain of sand stretching from northeastern Niger into western Chad, occupying an area of over . The Ténéré's boundaries a ...

Agadez Agadez ( Air Tamajeq: ⴰⴶⴰⴷⴰⵣ, ''Agadaz''), formerly spelled Agadès, is the fifth largest city in Niger, with a population of 110,497 based on the 2012 census. The capital of Agadez Region, it lies in the Sahara desert, and is also ...

, Niger. This rock unit dates to the late Aptian stage, approximately 115 million years ago. The bone was designated as the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

of a new species of ''

'' (''V. nigeriensis'') by

Peter Galton Peter Malcolm Galton (born 14 March 1942 in London) is a British vertebrate paleontologist who has to date written or co-written about 190 papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosa ...

and Taquet in 1982. It was differentiated from the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

''V. canaliculatus'' by the locations of

trochanter A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the anatomic "normal" includes ...

s and other details. Because ''V. canaliculatus'' is known from Europe, the presence of a related species in central Africa was interpreted as evidence for a land connection between the two continents. ''V. nigeriensis'' was given its own genus, ''Elrhazosaurus'', by Galton in 2009. This was done on the grounds of differing

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

and geologic age versus ''V. canaliculatus''. He retained it as a dryosaurid. While ''Elrhazosaurus'' is sometimes described as only known from thigh bones, at least one

upper arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

bone has been assigned to the genus.

Paleoecology and paleobiology

The Elrhaz Formation is mostly made up of fluvial

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

s. A diverse assemblage of fossil animals has been recovered, including freshwater bivalves,

hybodont Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern shar ...

sharks, bony fish, turtles, several genera of crocodylomorphs (''

Anatosuchus ''Anatosuchus'' ("duck crocodile", the name from the Latin ''anas'' ("duck") and the Greek ''souchos'' ("crocodile"), for the broad, duck-like snout) is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described ...

'', ''

Araripesuchus ''Araripesuchus'' is a genus of extinct crocodyliform that existed during the Cretaceous period of the late Mesozoic era some 125 to 66 million years ago. Six species of ''Araripesuchus'' are currently known. They are generally considered to be n ...

'', ''

Sarcosuchus ''Sarcosuchus'' (; ) is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the early Albian, 133 to 112 million years ago of what is now Africa and ...

'', and ''

Stolokrosuchus ''Stolokrosuchus'' is an extinct genus of neosuchian crocodylomorph that lived during the Early Cretaceous. Its fossils, including a skull with a long thin snout and bony knobs on the prefrontal, have been found in Niger. ''Stolokrosuchus'' wa ...

''), undescribed ornithocheirid

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 ...

s, the

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

dinosaurs ''

Eocarcharia ''Eocarcharia'' (meaning "dawn shark") is a genus of carcharodontosaurid theropod dinosaur from the Early Cretaceous Elrhaz Formation that lived in the Sahara 112 million years ago, in what today is the country of Niger. It was discovered in 2 ...

'', ''

Kryptops ''Kryptops'' is a genus of abelisaurid theropod dinosaur from the Early Cretaceous of Niger. It is known from a partial skeleton found at the Gadoufaoua locality in the western Ténéré Desert, in rocks of the Aptian-Albian age Elrhaz Formation ...

'', '' Suchomimus'', and an undescribed noasaurid (possibly ''

Bahariasaurus ''Bahariasaurus'' (meaning " Bahariya lizard") is an enigmatic genus of large theropod dinosaur. ''Bahariasaurus'' is known to have included at least 1 species, ''Bahariasaurus ingens'', which was found in North African rock layers dating to the ...

''), the sauropods ''

Nigersaurus ''Nigersaurus'' is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils of th ...

'' and an undescribed

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

ian (possibly ''

Malawisaurus ''Malawisaurus'' (meaning "Malawi lizard") is an extinct genus of titanosaurian sauropod dinosaur. It is known from the Dinosaur Beds of northern Malawi, which probably date to the Aptian stage of the Early Cretaceous. The type species is ''M. di ...

''), and the iguanodontians ''

Lurdusaurus ''Lurdusaurus'' ("heavy lizard") is a genus of massive and unusually shaped iguanodont dinosaur from the Elrhaz Formation in Niger. It contains one species, ''L. arenatus''. The formation dates to the Early Cretaceous, roughly 112 million years ...

'' and '' Ouranosaurus''. As a dryosaurid iguanodontian, ''Elrhazosaurus'' would have been a lightly built

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

bipedal Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...

runner Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions). This is ...

References

{{Taxonbar, from=Q2154452 Iguanodonts Early Cretaceous dinosaurs of Africa Aptian life Cretaceous Niger Fossils of Niger Fossil taxa described in 2009 Taxa named by Peter Galton Ornithischian genera