Published by the American Geophysical Union as part of the Field Trip Guidebooks Series, Volume 322. In the 1800s western North America was the site of a paleontological "gold rush". Collectors such as F.V. Hayden, J. Leidy, E.D. Cope, D.C. Marsh, J. Wortman, W.B. Scott, J. Tyrell, and the Sternbergs initiated an intensive, exciting, and romanticized phase of discovery of vertebrate fossils. Although the productivity of this period often is exaggerated, the quality and volume of material recovered is impressive. Hundreds of new taxa were named, including numerous fish, dinosaurs and other reptiles, and mammals. E. Douglass, B. Brown, E.C. Case, C.R. Eastman, E.S. Riggs, W.D. Matthew, H.F. Osborn, F.B. Loomis, W.J. Sinclair, W. Granger and others expanded the scope of collecting in this area throughout the early 1900s.