Anatomy: Ouranosaurus' sail was formed by long-spined vertebrae in the backbone. The spines stuck out from its back and tail; the spines were covered with skin. The sail was probably used for temperature regulation in the hot, African environment. It would help the animal cool down in the heat of day, by dispersing extra heat when the sail was turned away from the sun. It would also help Ouranosaurus collect heat early in the morning when the sail faced the sun. The sail may also have been used for mating displays, intraspecies rivalry, or to make it look larger when confronting predators. Ouranosaurus had few defenses.

Ouranosaurus was about 24 feet (7 m) long and may have weighed about 4 tons. Its skull was longer than other iguanodontid skulls. There was a bit of a crest on the snout, forming two bony bumps. The neck was short and flexible. There were five short fingers on each hand; the second and third fingers had hoof-like nails that Ouranosaurus probably used when it went on all four limbs to graze low-lying plants. Each thumb had a small conical spike like Iguanodon. It could probably walk on two or four legs.

Diet: Ouranosaurus was an herbivore, a plant eater. It probably ate leaves, fruit, seeds, and other plant material with its tough beak. It had no teeth in its beak, but had many cheek teeth that it used for grinding up tough plant material.

Fossils and Name: Ouranosaurus means "Brave Lizard." This dinosaur was named by the French paleontologist Phillippe Taquet in 1976. Two complete Ouranosaurus fossils were found in the southern Sahara Desert, in northeast Niger, Africa, in 1965.