Two new, extinct taxa of peccaries from upper Miocene deposits of the western Amazon Basin provide the first data documenting the presence of these North American mammals in South America in the Miocene. One, Sylvochoerus woodburnei n. gen. n. sp., is allied morphologically to Tayassu pecari, whereas the second, Waldochoerus bassleri n. gen. n. sp., is more similar to Pecari tajacu. Both new taxa reflect an intermediate position between middle Miocene peccaries and modern Tayassu and Pecari. The specimens reported here were unstudied, but when collected they were referred to living species of Tayassu and Pecari based on their general similarity to species of those two living genera, and they were dated to the Pleistocene, presumably based on a long–standing model of the Great American Faunal Interchange. The presence of peccaries in South America at approximately the same time that South American ground sloths began appearing in upper Miocene deposits of North America, and soon after the appearance of gomphotheres in South America, indicates that dispersal between the Americas was earlier and involved more taxa than previously interpreted. Molecular divergence data are consistent, in part, with a late Miocene dispersal of peccaries to South America.