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

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of basal

iguanodontia Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

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

, known from isolated bones found in

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

rocks of

Niger Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

. These bones were initially thought to belong to a species of the related dryosaurid ''

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

'', but have since been reclassified.

Discovery and history

''Elrhazosaurus'' is based on

MNHN The French National Museum of Natural History ( ; abbr. MNHN) is the national natural history museum of France and a of higher education part of Sorbonne University. The main museum, with four galleries, is located in Paris, France, within the ...

GDF 332, a left

thigh bone The femur (; : femurs or femora ), or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals the femur is the upper bone of the hindleg. The top of the femur fits in ...

collected by

Philippe Taquet Philippe Taquet (born 25 April 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 30 November 2004, president ...

from the upper part of the

Elrhaz Formation The Elrhaz Formation is a geological Formation (geology), formation in Niger, West 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 ...

of Gadoufaoua in the Ténéré Desert,

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 the eponymous Agadez Region, the city lies in the Sahara ...

, Niger. This rock unit dates to the late

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

stage, approximately 115 million years ago. The bone was designated as the

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

of a new species of ''

'' (''V. nigeriensis'') by Peter Galton and Taquet in 1982. It was differentiated from the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

''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 have two, sometimes three, trochanters. Etymology The anatomical term ' ...

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 The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the should ...

bone has been assigned to the genus.

Paleoecology and paleobiology

The Elrhaz Formation is mostly made up of

fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

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

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

hybodont Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays ( ...

sharks, bony fish, turtles, several genera of

crocodylomorphs Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ...

('' Anatosuchus'', ''

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. ''Araripesuchus'' is generally considered to be a notosuchian (belonging to the clade Mes ...

'', ''

Sarcosuchus ''Sarcosuchus'' (), from Ancient Greek σάρξ (''sárx''), meaning "flesh", and σούχος (''soúkhos''), meaning "crocodile", is an extinct genus of crocodyliform a that lived during the Early Cretaceous, from the late Hauterivian to the ...

'', and '' Stolokrosuchus''), undescribed

ornithocheirid Anhangueridae (alternatively called Ornithocheiridae, meaning "bird hands") is a group of pterosaurs within the suborder Pterodactyloidea. These pterosaurs were among the last to possess teeth. Members that belong to this group lived from the ...

pterosaur Pterosaurs are 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 million to 66 million years ago). Pterosaurs are the earli ...

s, the

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaurs ''

Eocarcharia ''Eocarcharia'' (meaning "dawn shark") is an extinct genus of theropod dinosaurs found in what is now the western Ténéré Desert of Niger. It is known from several skull bones collected in 2000 by an expedition to the Early Cretaceous (Aptian� ...

'', ''

Kryptops ''Kryptops'' (meaning "covered face") is an extinct genus of abelisaurid theropod dinosaurs from the Early Cretaceous of Niger. It is known from a partial maxilla (upper jaw bone) found at the Gadoufaoua locality in the western Ténéré Desert, ...

'', ''

Suchomimus ''Suchomimus'', from Ancient Greek ''σούχος'' (''soúkhos''), meaning "crocodile", and Latin ''mimus'', meaning "actor", is a genus of spinosaurid dinosaur that lived between 125 and 112 million years ago in what is now Niger, North A ...

'', and an undescribed noasaurid, 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 o ...

'' 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, 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 ''Ouranosaurus'' is a genus of herbivorous basal hadrosauriform dinosaur that lived during the Aptian stage of the Early Cretaceous of modern-day Niger and Cameroon. ''Ouranosaurus'' measured about long and weighed . Two rather complete fossils ...

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

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

bipedal Bipedalism is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) 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'' ...

runner.

References

{{Taxonbar, from=Q2154452 Dryosauridae Dinosaur genera Aptian dinosaurs Fossil taxa described in 2009 Taxa named by Peter Galton Dinosaurs of Niger