Ouranosaurus

About Ouranosaurus

Features of Ouranosaurus: Tall Spines on Its Back

Ouranosaurus had a long, narrow, and flat skull. It had a dome-like bump on its snout and small horns in front of its eyes.
It is a rare dinosaur among ornithopods to have horns, but these are thought to have been used not as weapons, but for communication and appeal among peers.

Its mouth had a broad beak like a duck-billed dinosaur, and it lacked front teeth. It was adapted to "bulk feeding," consuming large amounts of low-nutrient plants at once, such as ferns, conifers, cycads, or early angiosperms that had just begun to appear. At the back of its mouth was a "dental battery" tightly packed with countless teeth, with a mechanism where new teeth would grow from below as the old ones wore down.

Are the Tall Spines on Its Back a Sail or a Hump?

The most prominent feature of Ouranosaurus is the tall bony projections called "neural spines" that tower from its back to its tail.

It was once thought that thin skin was stretched across these bones to form a "sail" like that of Spinosaurus, acting as a radiator to regulate body temperature by basking in the sun. Also, in the 1990s, a theory was proposed that they were "fat humps" that stored energy to survive harsh droughts, similar to modern bison or camels.

However, these theories are no longer supported today.

Reasons why it is not considered a sail or a hump: It is known that the environment where Ouranosaurus lived was not a desert, but a wetland rich in water. Therefore, there was no need for it to have a "fat hump" like a camel. Furthermore, it is considered unlikely that a huge animal like a dinosaur would necessarily need such a large sail just for temperature regulation.

Today, like the dome and horns on its snout, its most likely role is considered to have been a "visual display (ornament)" used for warning or intimidating peers, or for appealing to the opposite sex.

How Ouranosaurus Walked and the Secret of Its Limbs

Its forelimbs were long, measuring more than half the length of its hind limbs. Also, its thumbs had sharp, conical spikes (claws), though they were smaller than those of its close relative, Iguanodon. On the other hand, its middle fingers were broad and had a hoof-like structure.

From the structure of its leg bones, it seems they were not very good at running. It is thought that they normally ate low-lying plants while walking stably on four legs, and when necessary, they stood on two legs to eat leaves from tall trees or ran short distances.

A Rich and Dangerous Paleoecosystem

Early Cretaceous Africa (current Republic of Niger), where Ouranosaurus lived, was not a harsh desert, but a lush wetland with flowing rivers.

Here, the ornithopod Lurdusaurus, which lived near the water like a hippopotamus, and the sauropod Nigersaurus, which ate ground-level grass, coexisted. They were able to thrive by dividing the plants they ate and the places they lived.

However, rich nature also attracts powerful carnivores. The giant carnivorous dinosaur Eocarcharia lurked on land, while Suchomimus (a relative of Spinosaurus) and the giant crocodile Sarcosuchus, which reached 9.5 meters in length, lurked near the water. For Ouranosaurus drinking at the water's edge, an ambush by a giant crocodile was a major threat.
The body mechanism that allowed for fast and large growth, as well as the conspicuous spines on its back, may have evolved to survive in such a dangerous environment and to coordinate with peers.

Discovery and Published Paper

Ouranosaurus fossils were discovered between 1965 and 1972 by an expedition led by the renowned French paleontologist Dr. Philippe Taquet in a region of the Sahara Desert called "Gadoufaoua" (meaning "the place where camels fear to go" in the local language).

Its scientific name, "Ouranosaurus," is derived from the Arabic word for "courage" as well as "ourane," meaning desert monitor in the language of the local nomadic Tuareg people. The Tuareg folklore features stories about the desert monitor, making it a name deeply connected to the culture of the excavation region.

Based on the exceptionally well-preserved skeleton, Dr. Taquet introduced this dinosaur to the world as a new genus and species in a research paper published in 1976 ( Géologie et paléontologie du gisement de Gadoufaoua (Aptien du Niger). Cahiers de Paléontologie, CNRS, Paris. by Philippe Taquet. 1976.） .

Excavated in Niger, West Africa, Ouranosaurus retains the transitional features of evolving into hadrosaurids, and is positioned as an important discovery for unraveling the evolution of dinosaurs on the African continent.