Lurdusaurus
Encyclopedia
Lurdusaurus is a genus
of large ornithopod
dinosaur
which lived in the Aptian
stage
of the Early Cretaceous
, sometime between 121 to 112 million years ago.
discovered the partial remains of a euornithopod in the Tenere
in Niger
. In 1988 Souad Chabli coined the name "Gravisaurus tenerensis" in her dissertation on the animal. Such a nomen ex dissertatione, however, remains an invalid name if not published together with a description. As Chabli had left the field of paleontology, the type species
Lurdusaurus arenatus was formally named by Taquet and Dale Russell
in 1999. The generic name is derived from Latin
lurdus, "heavy", with the same meaning as the original gravis. The specific name arenatus means "sandy", like "tenerensis" a reference to the Tenere desert.
The holotype
MNHN GDF 1700 was found in layers of the Elrhaz Formation
dating to the upper Aptian-lower Albian
. It consists of a partial skeleton with a fragmentary skull.
, the longest carnivorous dinosaur known to date, but probably with around the same mass, i.c 5.5 tonnes. In 2010 however, Gregory S. Paul
gave a lower estimate of seven metres and 2.5 tonnes. Due to a short lower leg, its torso was characteristically low-slung, with the abdomen as little as 2.4 ft (0.71m) above ground level, and the rib cage was extremely broad. Its neck was relatively longer (5.3 ft [1.6m]) and its tail relatively shorter than that of other euornithopods. Even more so than with other large basal
iguanodont
s, the forelimbs were extremely powerful, with the innermost digit of each hand consisting of little more than a very large conical claw, presumably used for defense. The broad shortened hand was adapted to carrying the weight of the animal. The foot was unusually constructed in that the foot bones (metatarsals) lacked solid contact with each other, as in animals that can widely splay the toes, and this arrangement also indicates the presence of a single foot pad, precluding any ability to run quickly.
Its overall body plan was therefore very unusual compared to other ornithopods, and its describers Taquet and Russell suggested that it would have looked superficially like an ankylosaur. Paleontologist Tom Holtz has suggested that, based on its overall stocky build, short limbs and splaying toes, it may have been led an aquatic or semi-aquatic, hippopotamus
-like lifestyle.
Due to its hefty and apparently ungainly build, Lurdusaurus was most likely a slow-moving animal, not built for speed and therefore probably not capable of fast retreats from predators. However, its low-slung torso, while prohibiting it from running at high speeds, would have given it a low centre of gravity, allowing it to suddenly wheel round to face an attacker. Its thumb claws would have been formidable weapons, able to inflict possibly fatal damage to a predator if a blow was delivered to the neck or flank.
, which some believe to be synonymous with the slightly earlier Baryonyx
from England
, and with the sympatric Ouranosaurus
, notable for its tall-spined vertebrae. The remains of the allosauroid theropod Eocarcharia
and the abelisauroid Kryptops
have also been found in the Aptian
of Niger.
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 large ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
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...
which lived in the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
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...
, sometime between 121 to 112 million years ago.
Discovery and naming
In 1965 Philippe TaquetPhilippe Taquet
Philippe Taquet 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...
discovered the partial remains of a euornithopod in the Tenere
Ténéré
The Ténéré 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...
in 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...
. In 1988 Souad Chabli coined the name "Gravisaurus tenerensis" in her dissertation on the animal. Such a nomen ex dissertatione, however, remains an invalid name if not published together with a description. As Chabli had left the field of paleontology, the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Lurdusaurus arenatus was formally named by Taquet and Dale Russell
Dale Russell
Dale A. Russell is a Canadian geologist/palaeontologist, currently Research Professor at The Department of Marine Earth and Atmospheric Sciences of North Carolina State University...
in 1999. The generic name is derived from 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...
lurdus, "heavy", with the same meaning as the original gravis. The specific name arenatus means "sandy", like "tenerensis" a reference to the Tenere desert.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
MNHN GDF 1700 was found in layers of the Elrhaz Formation
Elrhaz Formation
The Elrhaz Formation is a geological formation in Niger whose strata date back to the Early Cretaceous...
dating to the upper Aptian-lower Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
. It consists of a partial skeleton with a fragmentary skull.
Unusual build
Lurdusaurus was enormously heavily built. Taquet originally estimated a length of 30 ft (9m), 40% shorter than SpinosaurusSpinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
, the longest carnivorous dinosaur known to date, but probably with around the same mass, i.c 5.5 tonnes. In 2010 however, Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
gave a lower estimate of seven metres and 2.5 tonnes. Due to a short lower leg, its torso was characteristically low-slung, with the abdomen as little as 2.4 ft (0.71m) above ground level, and the rib cage was extremely broad. Its neck was relatively longer (5.3 ft [1.6m]) and its tail relatively shorter than that of other euornithopods. Even more so than with other large 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:...
iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
s, the forelimbs were extremely powerful, with the innermost digit of each hand consisting of little more than a very large conical claw, presumably used for defense. The broad shortened hand was adapted to carrying the weight of the animal. The foot was unusually constructed in that the foot bones (metatarsals) lacked solid contact with each other, as in animals that can widely splay the toes, and this arrangement also indicates the presence of a single foot pad, precluding any ability to run quickly.
Its overall body plan was therefore very unusual compared to other ornithopods, and its describers Taquet and Russell suggested that it would have looked superficially like an ankylosaur. Paleontologist Tom Holtz has suggested that, based on its overall stocky build, short limbs and splaying toes, it may have been led an aquatic or semi-aquatic, hippopotamus
Hippopotamus
The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...
-like lifestyle.
Defense
Contemporaneous dinosaurs
Lurdusaurus was contemporaneous with the bizarre large theropod SuchomimusSuchomimus
Suchomimus is a genus of large spinosaurid dinosaur with a crocodile-like mouth that lived sometime between 121-112 million years ago, during the late Aptian stage of the Cretaceous period in Africa.-Description:...
, which some believe to be synonymous with the slightly earlier Baryonyx
Baryonyx
Baryonyx is a genus of carnivorous saurischian dinosaur first discovered in clay pits just south of Dorking, England, and later reported from fossils found in northern Spain and Portugal. It is known to contain only one species, Baryonyx walkeri...
from England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, and with the sympatric Ouranosaurus
Ouranosaurus
Ouranosaurus is an unusual genus of herbivorous iguanodont dinosaur that lived during the early Cretaceous about 110 million years ago in what is now Africa. Ouranosaurus measured about seven to eight meters long...
, notable for its tall-spined vertebrae. The remains of the allosauroid theropod Eocarcharia
Eocarcharia
Eocarcharia 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 2000 on an expedition led by University of Chicago paleontologist Paul Sereno. The...
and the abelisauroid Kryptops
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...
have also been found in the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
of Niger.