It was an age of counterfeit giants, avaricious robber barons, corrupt politicians, intrepid pioneers, fierce Indian chiefs, and dinosaurs. The second half of the nineteenth century -- the so-called Gilded Age -- was a time when Americans were exploring the West and building a nation that would stretch from coast to coast. It was also a time of scientific ferment. Charles Darwin had shaken the very foundations of Victorian society with his theory of evolution by natural selection, and scientists across the civilized world were locked in a great battle over Darwin's idea. While the debate raged in Europe, the hunt for hard evidence increasingly focused on the American West, with its grand mesas, buttes, and badlands. "We must turn to the New World if we wish to see in perfection the oldest monuments of earth's history," advised Sir Charles Lyell, the father of modern geology, after a visit to America. "Certainly in no other country are these ancient strata developed on a grander scale or more plentifully charged with fossils." Could the answer to the history of life and the proof of evolution be found in those fossils? That was the question that two young American paleontologists--Edward Drinker Cope and Othniel Charles Marsh--set out to answer. But what began as a friendly contest quickly turned into bitter rivalry that would spill over into American science and politics and rage relentlessly for nearly three decades.          Cope and Marsh would battle on the prairies, in the halls of Congress, in science journals, and in the popular press. Both wealthy men, they launched lavish, western expeditions and raced across the plains and mountains searching for the remains of the magnificent beasts that once inhabited the continent. Along the way they would encounter George Custer, Sitting Bull, Buffalo Bill, and Red Cloud.          Among the most remarkable fossil discoveries of Cope and Marsh are a bevy of dinosaurs, including some of the best known beasts -- the Triceratops, the Stegosaurus, the Camarasaurus, and the Brontosaurus. Even today, Marsh holds the record for dinosaur discoveries.          Just as valuable, however, were some of Marsh's discoveries of ancient mammals and birds that provided the first real proof of Dar- win's theory--"The best support for the theory in twenty years," the great Darwin himself proclaimed.          The tale of Cope and Marsh is also the story of the rise of American science. When their story begins just after the Civil War, America was an intellectual backwater, with eminent scientists snookered by the great, fake stone statue The Cardiff Giant--a hoax unmasked by Marsh.          But even as Cope and Marsh waged war, they both fought to build up American science and its scientific institutions. Yet despite their discoveries and their Gilded Age celebrity, the names of Cope and Marsh have faded into the recesses of the library and archive. In The Gilded Dinosaur Mark Jaffe exhumes from those archives the notes, journals, and letters of Cope and Marsh to reanimate and retell one of the keenest rivalries in the history of science.