Just when you thought it was safe to swim in the Cretaceous period, a new species of dinosaur- larger than T.Rex– has been found in the Sahara. Called Spinosaurus, it was a 45-foot long predator armed with hooked claws and a three-foot spiked sail on its dorsal side. While scientists are stunned by its size, they’re even more amazed that the Spinosaurus lived in water.

Prior to this discovery, it was thought that dinosaurs were overwhelmingly land animals. But Spinosaurus‘s unique features would have adapted it to live in the rivers and marshes of 97 million years ago. It had slimmer thighs and short feet ending in paddles, perfect for swimming but not ideal for running after prey. Its nostrils were along its jaws, which made it able to submerge similar to a crocodile. Due to its long neck and heavy trunk, it probably couldn’t walk upright. Additionally, it had dense leg bones that probably aided its buoyancy in the water.

Even more terrifying was Spinosaurus‘s diet. This creature most likely dined on crocodiles and enormous sharks. In a river system once thought to have been inhabited only by plesiosaurs, the Spinosaurus would have been a top predator.

The first specimen of Spinosaurus was found in 1912, but was not properly identified; the remains were destroyed by an Allied bombing campaign of Munich in 1944. The bones, skull, and claws of Spinosaurus were recently discovered in the Moroccan Sahara by Dr. Nizar Ibrahim of the University of Chicago, who published his findings in the journal Science.