Como Bluff, a long ridge in Wyoming between Rock River and Medicine Bow, became one of the most important dinosaur localities in the American West after major discoveries began in 1877. Its exposed Sundance, Morrison, and Cloverly formations preserved rich Late Jurassic fossils, and rival collecting for O.C. Marsh and E.D. Cope made it central to early American paleontology. Quarries along the ridge produced dinosaurs such as Allosaurus, Apatosaurus, Diplodocus, and Stegosaurus, as well as mammals, pterosaurs, turtles, fish, and amphibians. Quarry 9 alone yielded about 250 mammal specimens, greatly expanding knowledge of Jurassic mammals and the Morrison ecosystem.