The “Bone Wars” was the name given to the great rush to find, collect, name, and describe dinosaur fossils discovered from areas in the western United States. The impetus to this fervor was the intense, bitter, personal rivalry between two American paleontologists: Othniel Charles Marsh (1831–1899) and Edward Drinker Cope (1840–1897).

Starting in the 1870s, both men—once friends—funded and led competing expeditions to sites in the western United States. Each was trying to discover and name more dinosaurs than the other. Their objectives were the remains of Late Jurassic dinosaurs in the Morrison formation located in numerous sites in Colorado and Como Bluff, Wyoming. Among the new dinosaurs they discovered were several well-known ones, such as Allosaurus, Apatosaurus (formerly known as Brontosaurus), Diplodocus, Camarasaurus, Triceratops, Camptosaurus, Ceratosaurus, and Stegosaurus. By the 1890s, the two men uncovered and described a total of some 136 species of dinosaurs between them, although later analysis of the fossils reduced this number somewhat.