Prothero begins with the "greenhouse of the dinosaurs," the global-warming episode that dominated the Age of Dinosaurs and the early Age of Mammals. He describes the remarkable creatures that once populated the earth and uses his experiences collecting fossils in the Big Badlands of South Dakota to sketch their world. He then discusses the growth of the first Antarctic glaciers, which marked the Eocene-Oligocene transition. In following this dramatic transformation, Prothero shares his anecdotes of excavations and activists and illuminates the controversies between colleagues that shape our understanding of the contemporary and prehistoric world. He concludes with observations about Nisqually Glacier and other locations that prove global warming is happening much quicker than previously predicted, irrevocably changing the balance of the earth's thermostat.