About 66 million years after two dinosaurs died apparently locked in battle on the plains of modern-day Montana, an unusual fight over who owns the entangled fossils has become a multimillion-dollar issue that hinges on the legal definition of “mineral.” The 9th U.S. Circuit Court of Appeals ruled last week that the “Dueling Dinosaurs” located on private land are minerals both scientifically and under mineral rights laws. The fossils belong both to the owners of the property where they were found and two brothers who kept two-thirds of the mineral rights to the land once owned by their father, a...