We humans are the inheritors of a dynasty that has reigned over the planet for nearly 66 million years, through fiery cataclysm and ice ages: the mammals. Our lineage includes saber-toothed tigers, woolly mammoths, armadillos the size of a car, cave bears three times the weight of a grizzly, clever scurriers that outlasted Tyrannosaurus rex, and even other types of humans, like Neanderthals. Indeed humankind and many of the beloved fellow mammals we share the planet with today; lions, whales, dogs, represent only the few survivors of a sprawling and astonishing family tree that has been pruned by time and mass extinctions. How did we get here?...Beginning with the earliest days of our lineage some 325 million years ago, Brusatte charts how mammals survived the asteroid that claimed the dinosaurs and made the world their own, becoming the astonishingly diverse range of animals that dominate today's Earth. Brusatte also brings alive the lost worlds mammals inhabited through time, from ice ages to volcanic catastrophes. Entwined in this story is the detective work he and other scientists have done to piece together our understanding using fossil clues and cutting-edge technology.