No abstract

No abstract

SUMMARY

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.

A new dromomerycine palaeomerycid artiodactyl, Surameryx acrensis new genus new species, from upper Miocene deposits of the Amazon Basin documents the first and only known occurrence of this Northern Hemisphere group in South America. Osteological characters place the new taxon among the earliest known dromomerycine artiodactyls, most similar to Barbouromeryx trigonocorneus, which lived in North America during the early to middle Miocene, 20–16 Ma. Although it has long been assumed that the Great American Biotic Interchange (GABI) began with the closure of the Isthmus of Panama in the late Pliocene, or ca. 3.0–2.5 Ma, the presence of this North American immigrant in Amazonia is further evidence that terrestrial connections between North America and South America through Panama existed as early as the early late Miocene, or ca. 9.5 Ma. This early interchange date was previously indicated by approximately coeval specimens of proboscideans, peccaries, and tapirs in South America and ground sloths in North America. Although palaeomerycids apparently never flourished in South America, proboscideans thrived there until the end of the Pleistocene, and peccaries and tapirs diversified and still live there today.

No abstract

No abstract

The origin and early evolution of South American rodents are ongoing subjects of debate.