About a hundred million years ago, a dinosaur more than 50 feet long prowled Morocco's ancient coastlines, using its croc-like skull to feed on fish and other animals. But scientists have debated how exactly this predator, called Spinosaurus aegyptiacus, pursued its prey in the water.

In 2014, a blockbuster paper by National Geographic Emerging Explorer Nizar Ibrahim argued that Spinosaurus spent most of its time in the water, perhaps swimming—or even diving—in pursuit of its aquatic prey, the first known dinosaur to do so. Now, a new study claims that despite its taste for fish, Spinosaurus may not have been a great swimmer after all.

The analysis, published in PeerJ on Thursday, used computer simulations to determine how the