The evolutionary history of vertebrate nonhuman animals such as mammals in what is now Latin America extends back tens of millions of years. Given that anatomically modern humans first appeared in Africa a mere 200,000 years ago and would not reach Latin America until some 12,000 years ago, nonhuman animals in the region evolved for most of their history without interference from human activities. Once they appeared, humans began to shape the history of the region’s animals in profound ways. In fact, one could argue that animal history in Latin America has been a story of increasing human impact; from the Paleo-Indians, who may have driven countless species of megafauna to extinction; to the agrarian societies that domesticated species such as dogs, turkeys, and llamas (or tolerated the animals’ self-domestication); to the radical transformations brought about by the Columbian Exchange; to the industrialization process of the last two centuries. But animal history in the region is also marked by adaptation and agency on the part of animals, who have influenced the course of human history. This dynamic and adaptive human–animal relationship has been pushed to the limit during extinction pulses, manifest in the currently accelerating biodiversity crisis. Environmental history makes the convincing case that any historical account that neglects the environment offers an inaccurate depiction of the past. By the same token, animal historians suggest that a more complete understanding of history requires redefining its boundaries to include the often underappreciated story of nonhuman species and their interrelationships with human societies.