Ouranosaurus (meaning "brave lizard"), was an extinct genus of ornithopod dinosaur that lived during the Early Cretaceous (Late Aptian Stage) about 110 million years ago in what is now modern day Niger And Cameroon. It was unique because it had a hadrosaur-like bill and a sail on its back, like Dimetrodon or Spinosaurus. This trait is not known in any other iguanodonts or hadrosauriforms besides Morelladon. Ouranosaurus measured about 7 meters (23-27 feet) long and weighed about 2-4 tons. Two complete fossils were found in the Echkar (or El Rhaz) Formation, Gadoufaoua deposits, Agadez, Niger in 1966 along with a third indeterminate specimen. The animal was named by a French paleontologist in 1976 called Philippe Taquet.
Ouranosaurus was named "brave" due to the fact that the nomadic people of the Sahara call a native species of monitor lizard, "ourane" which means brave. The resemblance was carried on.
Discovery and naming[]
Location of the Gadoufaoua within Niger
Five French palaeontological expeditions were done in the Gadoufaoua region of the Sahara Desert in Niger between 1965 and 1972 and led by French palaeontologist Philippe Taquet. The deposits of the region come from GAD 5, a layer in the upper Elrhaz Formation of the Tégama Group, which was deposited during the Aptian stage of the Early Cretaceous. The skeletons found in 1967 were brought to the Muséum National d'Histoire Naturelle of Paris, where they were prepared.
In January 1965 Philippe Taquet discovered dinosaurian fossils at the Camp des deux Arbres site near Gadoufaoua. The material was recovered in 1966. Taquet described the type species Ouranosaurus nigeriensis from the fossils in 1976. The generic name is derived from Tuareg ourane meaning "monitor lizard" — a totem animal to the Tuareg who consider it their ancestral maternal uncle — but itself related to Arab waran, "brave". The specific name refers to Niger.
The holotype specimen MNHN GDF 300, was found in the Upper Elrhaz Formation dating to the late Aptian or early Albian, about 112 to 110 million years old. It consists of an almost complete skeleton with skull, that is today mounted in the Nigerien capital Niamey; the Museum national d'histoire naturelle displays a cast. Other finds include the paratype specimen GDF 381, a second skeleton found in 1972, and the referred specimens GDF 301, a large coracoid, and GDF 302, a femur.
Description[]
Size of Ouranosaurus compared to a human
Ouranosaurus was a fairly large iguanodontian, Taquet estimated it to be 7 meters (23 feet) and weigh 4 tons.[1] The American paleontologist Gregory S. Paul in 2010 suggested a lighter weight of 2.2 tons and estimated a longer length of 8 meters (23 feet). Bertozzo et al. in 2017, suggested that the Holotype and Paratype belonged to subadult specimens, although they would have been close to adult size. MSNVE 3714 is 6.5 m (21 ft) long as mounted, although a few caudals are missing, and is roughly 90% the length of the holotype, which would be 7.22 m (23.7 ft) long. The variation between the sizes fits within the range of variation between adult individuals of Iguanodon, so there is a chance that the larger holotype and smaller paratype were same ontogenetic stage.
Skull[]
Skull
Ouranosaurus had a skull 67 centimetres long. The head was unusual in being very elongated and flat. It carried a much longer snout than its relative Iguanodon; this rostrum was not curved but straight, off-set from the back of the skull in an oblique line. The snout was toothless and covered in a horny sheath during life, forming a very wide beak together with a comparable sheath on the short predentary bone at the extreme front of the lower jaws. However, after a rather large diastema with the beak, there were large batteries of cheek teeth on the sides of the jaws: the gaps between the teeth crowns were filled by the points of a second generation of replacement teeth, the whole forming a continuous surface. Contrary to the situation with some related species, a third generation of erupted teeth was lacking. There were twenty-two tooth positions in both lower and upper jaw for a total of eighty-eight.
The jaws were apparently operated by relatively weak muscles. Ouranosaurus had only small temporal openings behind the eyes, from which the larger capiti-mandibularis muscle was attached to the coronoid process on the lower jaw bone. Small rounded horns in front of its eyes made Ouranosaurus the only known horned Ornithopod. The back of the skull was rather narrow and could not compensate for the lack of a greater area of attachment for the jaw muscle, that the openings normally would provide, allowing for more power and a stronger bite. A lesser muscle, the musculus depressor mandibulae, used to open the lower jaws, was located at the back of the skull and was connected to a strongly projecting, broad and anteriorly oblique processus paroccipitalis. Ouranosaurus probably used its teeth to chew up tough plant food. A diet has been suggested of leaves, fruit, and seeds as the chewing would allow to free more energy from high quality food; the wide beak on the other hand indicates a specialisation in eating large amounts of low quality fodder. Ouranosaurus lived in a river delta.
Restoration of the head displaying "nasal protuberances"
The nasal passage was large and placed close to the beak. The nostrils were in a high position. On each side of the top of the skull there was a low bump between the nasal opening and the eye socket; the significance of both protuberances is unknown, but they may have been used for socialisation or mating displays. A secondary palpebral bone was lacking.
Postcranial skeleton[]
Mounted skeleton cast, ROM
The most conspicuous feature of Ouranosaurus is a large "sail" on its back, supported by long, wide, neural spines, that spanned its entire rump and tail, resembling that of Spinosaurus, a well-known meat-eating dinosaur that lived around the same time.[2] These tall neural spines did not closely resemble those of sail-backs such as Dimetrodon of the Permian Period. The supporting spines in a sailback become thinner distally, whereas in Ouranosaurus the spines actually become thicker distally and flatten. The posterior spines were also bound together by ossified tendons, which stiffened the back. Finally, the spine length peaks over the forelimbs.
The first four dorsal vertebrae are unknown; the fifth already bears a 32 centimetres long spine that is pointed and slightly hooked; Taquet presumed it might have anchored a tendon to support the neck or skull. The tenth, eleventh and twelfth spines are the longest at about 63 centimetres. The last dorsal spine, the seventeenth, has a grooved posterior edge, in which the anterior corner of the lower spine of the first sacral vertebra is locked. The spines over the six sacral vertebrae are markedly lower, but those of the tail base again longer; towards the end of the tail the spines gradually shorten.
Dorsal vertebrae
The dorsal "sail" is usually explained as either functioning as a system for thermoregulation or a display structure. An alternative hypothesis is that the back might have carried a hump consisting of muscle tissue or fat, resembling that of a bison or camel, rather than a sail. It could have been used for energy storage to survive a lean season.[3]
The axial column consisted of eleven neck vertebrae, seventeen dorsal vertebrae, six sacral vertebrae and forty tail vertebrae. The tail was relatively short.
The front limbs were rather long with 55% of the length of the hind limbs. A quadrupedal stance would have been possible. The humerus was very straight. The hand was lightly built, short and broad. On each hand Ouranosaurus bore a thumb claw or spike that was much smaller than that of the earlier Iguanodon. The second and third digits were broad and hoof-like, and anatomically were good for walking. To support the walking hypothesis, the wrist was large and its component bones fused together to prevent its dislocation. The last digit (number 5) was long. In related species the fifth finger is presumed to have been prehensile: used for picking food like leaves and twigs or to help lower the food by lowering branch to a manageable height. Taquet assumed that with Ouranosaurus this function had been lost because the fifth metacarpal, reduced to a spur, could no longer be directed sideways.
Restoration of Ouranosaurus nigeriensis based on skeletal diagrams and casts, fossils, and related species
The hindlimbs were large and robust to accommodate the weight of the body and strong enough to allow a bipedal walk. The femur was slightly longer than the tibia. This may indicate that the legs were used as pillars, and not for sprinting. Taquet concluded that Ouranosaurus was not a good runner because the fourth trochanter, the attachment point for the large retractor muscles connected to the tail base, was weakly developed. The foot was narrow with only three toes and relatively long.
In the pelvis, the prepubis was very large, rounded and directed obliquely upwards.
History[]
Two almost complete Ouranosaurus fossils were found in the southern Sahara Desert, in northeast Niger, in 1966. Spinosaurus, a large, sail-backed meat-eater, was one of its contemporaries in the hot, Cretaceous environment of north Africa. Ouranosaurus was named by the French paleontologist Phillippe Taquet in 1976.
Classification[]
Taquet first assigned Ouranosaurus to the Iguanodontidae, in the larger Iguanodontia. But, while it shares some traits of Iguanodon (such as a thumb spike), Ouranosaurus is no longer placed in the iguanodontid family. It is now placed in the clade Hadrosauroidea, which contains the Hadrosauridae (aka "duck-billed dinosaurs") and their close relatives.
Paratype MSNVE 3714 in front view
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Paleobiology[]
Diet[]
The jaws were apparently operated by relatively weak muscles. Ouranosaurus had only small temporal openings behind the eyes, from which the larger capiti-mandibularis muscle was attached to the coronoid process on the lower jaw bone. Small rounded horns in front of its eyes made Ouranosaurus the only known horned ornithopod. The back of the skull was rather narrow and could not compensate for the lack of a greater area of attachment for the jaw muscle, that the openings normally would provide, allowing for more power and a stronger bite. A lesser muscle, the musculus depressor mandibulae, used to open the lower jaws, was located at the back of the skull and was connected to a strongly projecting, broad and anteriorly oblique processus paroccipitalis. Ouranosaurus probably used its teeth to chew up tough plant food. A diet has been suggested of leaves, fruit, and seeds as the chewing would allow to free more energy from high quality food; the wide beak on the other hand indicates a specialisation in eating large amounts of low quality fodder. Ouranosaurus lived in a river delta.
Histology[]
Ouranosaurus bears more similarities to other derived iguanodonts than more basal ornithopods. Remodeling is present in the subadult paratype, and high vascular density and circumferential arrangement of the microstructure suggests fast growth. Faster growth occurs in the same phylogenetic groups as higher body size, although their relationship is unclear. Ouranosaurus is a similar size to more basal Tenontosaurus which has slow growth, so either faster growth is caused by body size or Tenontosaurus is the maximum size of an ornithopod with a slow growth rate.
Suchomimus and Nigersaurus in the environment of the Elrhaz Formation
Paleoecology[]
The Elrhaz Formation is situated in the Sahara Desert, however in the Cretaceous it featured wide rivers and lush tropical foliage. Other herbivorous dinosaurs found in this formation include the small and agile Elrhazosaurus and the large water dwelling Lurdusaurus. These dinosaurs would have been prey for the large carnivorous Eocarcharia and the abelisaurid Kryptops. The largest carnivorous dinosaur in this formation was Suchomimus, however it was primarily a fish eater. The most dangerous animal by far though was the huge crocodilian Sarcosuchus.
JPInstitute.com Description[]
Ouranosaurus was a cousin to the better known Iguanodon. There was one big difference between the two, however, in the way that these dinosaurs looked. Ouranosaurus had long spines along its back, some up to two feet long. These probably supported a fin that ran all the way down its tail, almost to the tip.
A nearly complete skeleton of Ouranosaurus was discovered in Niger in 1976, providing an excellent look at this unique African dinosaur. Other than its long neural spines, it had similar characteristics to other iguanodontids - thumb spikes, beak, etc.
Appearance in other media[]
Jurassic Park[]
- It also appears in Jurassic Park: Operation Genesis as a dinosaur the player is able to place in their park.
- Ouranosaurus also appears in Jurassic Park Builder as a gold herbivore. It, however, vaguely resembles the real creature. It lacks its thumb claw, the sail is too small, and its hadrosaur-like beak is missing.
- Ouranosaurus appeared in the video game Jurassic World: Alive, as an Epic creature, and spawns often in Bank areas, the game requires you to dart 150 Ouranosaurus DNA to unlock it.
- Ouranosaurus appeared in the video game Jurassic World: Evolution’s Claire’s Sanctuary DLC, as one of the new dinosaurs.
- Ouranosaurus appeared in Jurassic World: Camp Cretaceous, where it was depicted to be highly territorial, very aggressive, and rather dim-witted.
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Read more Ouranosaurus on Jurassic Park Wiki |
The Land Before Time[]
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Read more Ouranosaurus on Land Before Time Wiki |