Gigantic dinosaurs frolicked and splashed some 170 million years ago in the lagoons of what is now Scotland. That’s what a team of paleontologists has determined after discovering dozens of jumbo-sized footprints belonging to long-necked sauropods on the Isle of Skye. Mixed with the herbivores’ tracks were a few clawed impressions left behind by two-legged meat-eaters known as theropods. The footprints present a snapshot of life during an important period in dinosaur history that has yielded relatively few fossil remains. In the mid-Jurassic, sauropods necks grew longer and the first birds were figuring out flight.Identifying two types of footprints in...