Spinosaurus

In a murky river that cuts through North Africa, a 50-foot-long hunter swims after a fish the size of a car. It sports six-inch-long teeth and a sail on its back with spines the size of surfboards. The hungry stalker closes in on the fish, gobbling up the meal. Then it glides away in search of more snacks. The creature isn’t some sort of enormous shark or a vicious crocodile. It’s a dinosaur called Spinosaurus, and it’s the only known dino that’s thought to have dwelled in water.

The reptile’s dense bones—which resemble those of modern-day aquatic creatures such as the manatee—helped it float better. And its paddle-like webbed feet would’ve allowed the animal to swim. Even the dinosaur's sail—which likely stuck out of the water while Spinosaurus was swimming—helped the animal survive in its river home.

Making waves

Named for its seven-foot-long spines, Spinosaurus lived about a hundred million years ago during the Cretaceous period. It inhabited what is now North Africa’s Sahara region, which at the time featured a large river system. Spinosaurus was well adapted for aquatic life. Its nostrils were further up on its snout than the nostrils of other dinosaurs. This would’ve allowed the animal to breathe even with most of its snout submerged. Its crocodile-like teeth were ideal for catching fish. This dinosaur had flight feathers on both its front and back limbs, and it had long upper arm bones similar to those seen in today’s birds. It also had a fan of feathers on its tail that it might have used to steer as it coasted to the ground. Scientists have discovered that its feathers were iridescent, meaning they had a metallic shine similar to the feathers of modern peacocks and hummingbirds.

Set sail

Scientists believe that Spinosaurus may have used its sail as a warning signal to intruders. The sight of the sail jutting out of the water would tell others to back off—unless they wanted a fight. You wouldn’t want to mess with this splashy creature!