For years, controversy has swirled around how a Cretaceous-era, sail-backed dinosaur—the giant Spinosaurus aegyptiacus—hunted its prey. Spinosaurus was among the largest predators ever to prowl the Earth and one of the most adapted to water, but was it an aquatic denizen of the seas, diving deep to chase down its meals, or a semiaquatic wader that snatched prey from the shallows close to shore?