In the dust of the Gilded Age Bone Wars, two vastly different men emerge with a mission to fill the empty halls of New York’s struggling American Museum of Natural History: Henry Fairfield Osborn, a privileged socialite whose reputation rests on the museum’s success, and intrepid Kansas-born fossil hunter Barnum Brown. When Brown unearths the first Tyrannosaurus Rex fossils in the Montana wilderness, forever changing the world of paleontology, Osborn sees a path to save his museum from irrelevancy. With four-foot-long jaws capable of crushing the bones of its prey and hips that powered the animal to run at speeds of 25 miles per hour, the T. Rex suggests a prehistoric ecosystem more complex than anyone imagined. As the public turns out in droves to cower before this bone-chilling giant of the past and wonder at the mysteries of its disappearance, Brown and Osborn together turn dinosaurs from a biological oddity into a beloved part of culture. Vivid and engaging, journeys from prehistory to present day, from remote Patagonia to the unforgiving badlands of the American West to the penthouses of Manhattan. With a wide-ranging cast of robber barons, eugenicists, and opportunistic cowboys, best-selling author David K. Randall reveals how a monster of a bygone era ignited a new understanding of our planet and our place within it.