Spanish scientists may have answered the long-debated question: Did dinosaurs swim? A team has discovered 125 million-year-old scratch marks in northern Spain, which they believe were made by theropods—the big-legged, skinny-armed family to which Tyrannosaurus rex belonged—clawing at the sediment with their hind legs as they forded through 10 feet of water or so. The 50-foot stretch of tracks indicates a stride of eight feet and a paddling motion similar to modern ducks, according to a study to be published this June in Geology.