Understanding the timing of mountain building and desert formation events in western North America is crucial to understanding the evolutionary history of the diverse arid-adapted biota that is found there. While many different, often conflicting descriptions exist regarding geobiotic change in western North America, little work has been done to synthesize these various viewpoints. In this paper we present several case studies that illustrate the differences in the various explanations, based on geological and paleobiological data, detailing mountain uplift and desertification in western North America. The majority of the descriptions detailing mountain building in this area fall into two major periods of uplift, the Laramide uplift [...]