THE NORTH AMERICAN FOSSIL RECORD OF BATS (MAMMALIA:CHIROPTERA) FROM CAVE AND KARST DEPOSITS

ABSTRACT:

Bats are the group of mammals most closely associated with caves. More than half of the 45 living species of bats from temperate North America (NA) are cave-dwellers in the families Vespertilionidae, Molossidae, Phyllostomidae, and Mormoopidae. Bats that inhabit caves also die in caves, leaving their skeletons to become preserved in fossil de- posits on the cave floor. During the latter half of the Pleistocene epoch (~10 ka to 1 Ma), bats have an excellent fossil record in NA caves, primarily vespertilionids of extant species. We recognize only two extinct species of vespertilionids, Myotis rectidentis (late Pleistocene) and Corynorhinus alleganiensis (middle Pleistocene). Two other extinct bats are known from late Pleistocene cave deposits in the US: a large vampire, Desmodus stocki (Phyllostomidae), in 8 caves in the southern US, 4 in Mexico, and 6 karst deposits in Florida, and the extinct mustached bat, Pteronotus pristinus (Mormoopidae) of Cuba, but is also known from a karst deposit in Florida. The record of bats from late Pleistocene cave deposits in Mesoamerica consists of 11 caves in Mexico and 1 in Belize. The only other extinct Pleistocene bat in Mesoamerica besides Desmodus stocki is the giant vampire, D. draculae, known from Loltún Cave in Mexico and Ce- bada Cave in Belize. A diverse fauna of Quaternary bats is known from several hundred cave deposits across the West Indies, including more extinct species (eight) than are found in Pleistocene deposits in continental NA: six extinct spe- cies from Cuba, Pteronotus pristinus and Mormoops magna (Mormoopidae; also known from Hispaniola) and Artibeus anthonyi, Cubanycteris silvai, Phyllops silvai, and Phyllops vetus (Phyllostomidae); Tonatia saurophila (Phyllostomidae) known only from Jamaica; and Phyllonycteris major (Phyllostomidae) from Puerto Rico, Antigua, and Marie Galante. There are also 18 living species of bats that underwent local extinction on one or more Antillean islands during the Holocene, including the extant vampire bat Desmodus rotundus in Cuba. The oldest NA cave deposits containing fossil bats are early Pleistocene in age (~0.8–1.0 Ma) in West Virginia, Texas, Colorado, and New Mexico. NA bat fossil sites older than early Pleistocene are primarily paleokarst deposits (sinkholes, fissures, solution cavities) in peninsular Florida. The richest of these are: Inglis 1A (early Pleistocene, ~2 Ma), with 7 species, including the oldest NA record of Desmodus and the only eastern NA record of Antrozous; Thomas Farm (early Miocene,~18 Ma), a sediment-filled sinkhole/cave complex containing 9 species including Primonatalus prattae, the oldest named species in the strictly cave-dwelling family Natalidae, Floridopteryx poyeri in the Emballonuridae; and 3 extinct genera of vespertilionids, Karstala, Miomyotis, and Suaptenos; and two Oligocene (26–30 Ma) fissure fills, I-75 and Brooksville 2, with 7 species of bats, including Koopmanycteris palaeomormoops, the oldest member of Mor- moopidae; 2 species of Speonycteris representing an extinct family (Speonycteridae) with Neotropical affinities; and Oligopteryx floridanus and O. hamaxitos, the earliest New World emballonurids. Although karstic deposits are widely distributed in NA, they mostly lack fossil bats, except in Florida. We suspect undiscovered Tertiary karst deposits with bats exist elsewhere in NA.