A new early Miocene bat (Chiroptera: Phyllostomidae) from Panama confirms middle Cenozoic chiropteran dispersal between the Americas

Fossils of an insectivorous bat from the early Miocene of Panama are described as a new genus and species, Americanycteris cyrtodon (Chiroptera: Phyllostomidae: Phyllostominae). Americanycteris is a large phyllostomine bat, similar in size to the living species Chrotopterus auritus. Americanycteris cyrtodon can be distinguished from other closely related species by a posteriorly curved p4 and a thick labial cingulum on m1. Americanycteris cyrtodon occurs in two early Miocene vertebrate faunas from Panama. The holotype mandible with p4–m1 and an isolated p3 of A. cyrtodon were recovered from the early Hemingfordian (19–18 Ma) Centenario Fauna, and a mandible with p2 was found in the older late Arikareean (21 Ma) Lirio Norte Local Fauna. A similar large phyllostomine bat is known from the early Miocene Gran Barranca Fauna in Argentina. The presence of early Miocene phyllostomids in both North America and South America confirms the overwater dispersal of bats between the Americas before the late Miocene onset of the Great American Biotic Interchange. Pre-late Miocene chiropteran dispersals between the Americas were previously documented for the Emballonuridae and Molossidae. Although the five endemic New World families in the Noctilionoidea, including Phyllostomidae, were previously thought to be South American in origin, the oldest fossil records of noctilionoids (Mormoopidae and extinct Speonycteridae) are from the early Oligocene of Florida and one of the earliest records of the Phyllostomidae is from the early Miocene of Panama. The currently available fossil records from Panama and Florida suggest a possible North American origin for the Noctilionoidea.