Why should someone write a book about the history of mammals in South America, and why should others read it? For a start, there are many strange animals in South America, fascinating to almost everyone: opossums, armadillos, tree sloths, anteaters, monkeys in great varieties, capybaras, wild guinea pigs, tucu-tucus, and many other native rodents, jaguars and rather weird maned wolves, tapirs, peccaries, llamas, to name just a few. Here is indeed an interesting mixture of creatures, and it takes only a modicum of human curiosity to want to know their history and to learn, as far as possible, how that mixture arose.
It is a mixture. Some of those animals have had ancestors and relatives confined to South America at the beginning of the Age of Mammals and long thereafter, although some have more recently spread into tropical Central American and a few even into the United States. Some appear suddenly in the middle of the history, while others appear rather later in this history as migrants from North America. This is a study of those historical mixtures.