Rafting on a wide and wild ocean
Résumé
Scientists first met with skepticism the notion that small mammals crossed large oceanic barriers to populate faraway lands. However, progress in phylogenetics during the 1980s forced researchers to admit that the excellent North American fossil record showed no relatives of South American caviomorph rodents or platyrrhine (New World) monkeys, and that their closest relatives lived on the Afro-Arabian landmass during the Eocene epoch (56 to 34 million years ago). Therefore, to reach South America, these animals would have had to cross the South Atlantic Ocean—which probably was more than 1500 to 2000 km wide during this period. On page 194 of this issue, Seiffert et al. (1) report on fossils, from Santa Rosa in Amazonian Perú, that provide evidence of a third mammalian lineage of African origin that briefly appeared in South America in the early Oligocene (35 to 32 million years ago): a now-extinct parapithecid anthropoid monkey (genus: Ucayalipithecus).