Opossums (Didelphidae) and bats (Noctilionidae and Molossidae) from the Late Miocene of the Amazon Basin

Fossil mammalian teeth recovered in sedimentary beds along the Rio Acre in western Amazonia include at least two kinds of Didelphidae (genera and species indeterminate) and the second Tertiary record for the Neotropical family Noctilionidae. The specimens form a part of the Rio Acre local fauna, probably representing the Huayquerian land-mammal age (ca. 9-5 X 10(6) years ago). The fossil bat from the Rio Acre is a single tooth that is smaller than the equivalent tooth in either of the two extant species of Noctilionidae and represents a new species of Noctilio, named herein. A second fossil bat was found ca. 120 km from the first along the Rio Purus. It is a molossid of indeterminate genus and species. These are the first Tertiary fossils of bats from the Amazon River Basin and the only South American fossil bats from ca. 12-1 X 10(6) years ago.