FOSSIL BATS OF THE AMERICAS
The White Springs LF is derived from siliciclastic sediments of the Parachucla Formation along the Suwannee River near White Springs in Columbia and Hamilton counties in northernmost peninsular Florida (Morgan 1989a; MacFadden and Morgan, in press). The Parachucla Formation is a predominantly marine unit containing sharks, fish, and sea cows, as well as a diverse fauna of marine mollusks, but also contains well-preserved terrestrial mammals. The White Springs LF has skulls and articulated skeletons of a new species of the oreodont Mesoreodon (MacFadden and Morgan, in press), three camelids, including Oxydactylus and Nothokemas waldropi, the horse Anchippus texanus, the rodents Protosciurus, Nototamias, Heliscomys, Arikareeomys, Proheteromys, and Leidymys, two genera and species of vespertilionid bats, as well as the sirenians Crenatosiren olseni, Dioplotherium manigaulti, and Metaxytherium sp. The vespertilionid bats are represented by seven isolated teeth.
The White Springs LF includes a number of mammalian taxa indicative of an early Arikareean (Ar2) age (from Morgan 1989a; MacFadden and Morgan, in press): the oreodont Mesoreodon; the lagomorph Megalagus; the rodents Protosciurus, Arikareeomys, Heliscomys, and Leidymys; and the sirenian Crenatosiren. Mesoreodon, Megalagus, Arikareeomys, Leidymys, and Protosciurus do not occur after the early Arikareean, and Crenatosiren is found only in late Oligocene (Chattian) marine faunas. Arikareeomys, Leidymys, and Protosciurus also occur in the late early Arikareean (Ar2) McCann Canyon LF in Nebraska (Korth 1992). Strontium isotope geochronology on oyster shells from White Springs yielded an age estimate of 24.4 Ma (Jones et al. 1993), which is in very close agreement with the late early Arikareean age (late Ar2, 24-25 Ma) suggested by the mammalian biochronology.