A giant fossil, unearthed in the Sahara desert, has given scientists a unique look at the largest-known carnivorous (meat eating) dinosaur: Spinosaurus.
The 95-million-year-old remains confirm a long-held belief that this is the first-known swimming dinosaur.
Scientists say the beast had flat, paddle-like feet and a long head like a crocodile, that would've allowed it to dive with ease.
Nizar Ibrahim, a dinosaur expert from the University of Chicago, said: "It is a really bizarre dinosaur."
"It has a long neck, a long trunk, a long tail, a 7ft (2m) sail on its back and a snout like a crocodile."
Spinosaurus remains were first discovered about 100 years ago in Egypt, and were moved to a museum in Germany.
But, they were destroyed during World War II, when a bomb hit the building.
The new fossil, which was found in the Kem Kem fossil beds in Morocco, has provided scientists with a more detailed look at the dinosaur.
The team says that Spinosaurus was a scary beast and may even have been bigger even than the mighty Tyrannosaurus rex.
Dr Ibrahim explained: "The one thing we noticed was that the proportions were really bizarre. The hind limbs were shorter than in other predatory dinosaurs, the foot claws were quite wide and the feet almost paddle shaped."
He added: "We thought: 'Wow - this looks looks like adaptations for a life mainly spent in water.'"
"And then we noticed other things. The snout is very similar to that of fish-eating crocodiles, with interlocking cone-shaped teeth."
"And even the bones look more like those of aquatic animals than of other dinosaurs. They are very dense and that is something you see in animals like penguins or sea cows, and that is important for buoyancy in the water," he said.
'Feasting on giant sharks'
The researchers say that Spinosaurus lived in a place they describe as "the river of giants", an area of water that would have stretched from Morocco to Egypt.
They believe the creature would have feasted on giant sharks and other car-sized fish called coelacanths and lungfish, competing with enormous crocodile-like creatures for its prey.
The research is published in the journal Science.