In the late 19th century, paleontologists Edward Cope and O.C. Marsh uncovered the remains of hundreds of prehistoric animals in the American West, including dozens of previously undiscovered dinosaur species. In the summer of 1868, paleontologist Othniel Charles Marsh boarded a Union Pacific train for a sight-seeing excursion through the heart of the newly-opened American West. While most passengers simply saw magnificent landscapes, Marsh soon realized he was traveling through the greatest dinosaur burial ground of all time. Ruthless, jealous and insanely competitive, Marsh would wrestle over the discovery with the other leading paleontologist of his generation, Edward Drinker Cope. Over time, the two rivals would uncover the remains of dozens of prehistoric animals, including over 130 dinosaur species, collect thousands of specimens, provide ample evidence to prove Charles Darwin’s hotly disputed theory of evolution and put American science on the world stage. The phrase “survival of the fittest” came to define both the science and the business of the day as ambitious men scrambled for control of unclaimed wealth on the western frontier. For Edward Cope and Othniel Marsh, the prize was not timber, land, or metals, but fossil bones, dinosaurs, sea monsters and primitive mammals, embedded in the rugged landscapes of the American West. The new transcontinental railroad put the ancient bone yards within reach of science for the first time. At stake in the vast and varied fossil fields of the West was an opportunity for someone to piece together and explain nothing less than the history of life on Earth. For almost 30 years, Cope and Marsh competed ruthlessly for that distinction. Under their influence, science in the United States emerged from the shadow of Europe and matured into a robust, cutthroat, quintessentially American enterprise. Cope and Marsh launched America’s love affair with dinosaurs and the prehistoric past that continues to this day, but they also managed to destroy each other in the process.