Largest known predatory dinosaur spent its life in water, study says

University of Chicago Paleontologists Paul C. Sereno speaks during an interview in front of a 50-foot life-size model of a Spinosaurus dinosaur at the National Geographic Society exhibit in Washington, Wednesday, Sept. 10, 2014. (AP / Pablo Martinez Monsivais)

Move over, T. rex – there's a new king of the dinosaurs now.

Scientists have identified the first known aquatic predatory dinosaur to date, a pre-historic behemoth with a frill on its back called Spinosaurus aegyptiacus.

Fossils indicate the Spinosaurus was the largest known predator to walk the Earth, with a body length stretching almost 3 metres longer than the largest-known Tyrannosaurus Rex specimen. Spinosaurus spent most of its life submerged in water, scientists say. It's the first known dinosaur to have lived and hunted in a semi-aquatic environment.

A team of scientists funded by the National Geographic Society announced their findings on Thursday. Their work is published in the journal Science, and in the latest edition of National Geographic, out on Thursday.

Spinosaurus isn't entirely new to the scientific community, but lack of fossil evidence has made it difficult for scientists to study its lifestyle.

The Spinosaurus study says recently discovered fossils have provided compelling evidence as to its aquatic lifestyle. The newest fossils were unearthed in the Sahara Desert in Morocco, and included a partial skeleton of the extinct creature.

Scientists created a three-dimensional model of the dinosaur by scanning the Morocco fossils and comparing them to other Spinosaurus fossils from various museum collections. Scientists used the 3-D guide to recreate a life-sized model of the dinosaur for study.

Lead study author Nizar Ibrahim said he's never seen anything like the Spinosaurus fossils. "Working on this animal was like studying an alien from outer space," he said in a statement on Thursday.

The study found that the 15-metre Spinosaurus had evolved to spend nearly its entire life in the water. The dinosaur had nostrils near the top of its head, allowing it to breathe with most of its body submerged. It also had teeth designed for catching fish, and dense bones that allowed it to control its buoyancy in water.

With a long neck, wavy tail and powerful thighs, Spinosaurus was more adapted for paddling in the water than walking on land, the study says. The creature also had a massive dorsal fan on its back.

The Morocco fossils were found near a series of cliffs that were riverbanks some 95 million years ago, when the Spinosaurus walked the Earth during the Cretaceous era.

A version of the Spinosaurus appeared in the 2001 film “Jurassic Park III,” where it was depicted as an amphibious predator capable of killing a T. rex. However, much of the film shows the Spinosaurus running on land, rather than swimming in water.