Spinosaurus ("spined lizard") was a theropod dinosaur that existed in what is now North Africa during the CretaceousPeriod. Spinosaurus is the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus rex andGiganotosaurus. Estimates published in 2014, and based on more complete specimens, found that Spinosaurus could reach lengths greater than 15 m (49 ft).
Its most distinctive feature was the huge sail-like fin on its back. This sail was made from spines that some out of the top of the backbones of all dinosaurs and all other backboned animals. The spines of Spinosaurus, were tremendous: The longest one found was over 1.7 meter (5 feet) tall! It may have served to let Spinosaurus cool itself down if it got too hot. The skin on the sail, like all skin, would have been filled with blood vessels. Hot blood pumped into the sail would be cooled off, especially if there was a breeze; African elephants use blood vessels in their ears for this purpose.
Additionally, the dinosaur may have used its sail to make itself look bigger. If a Spinosaurus turned itself sideways towards an attacker, it would suddenly look much larger, and so the other predator might think twice about attacking. Also, the sail might have been used to show off to attract a mate.
The jaws were long and slender, and the teeth were cone-shaped, like those of a crocodile. Evidence suggests that it lived both on land and in water as a modern crocodilian does.