As explorers and scientists have known for decades, the Neotropics harbor a fantastic array of our planet's mammalian diversity, from capybaras and capuchins to maned wolves and mouse opossums to sloths and sakis. This biological bounty can be attributed partly to the striking diversity of Neotropical landscapes and climates and partly to a series of continental connections that permitted intermittent faunal exchanges with Africa, Antarctica, Australia, and North America.