FOSSIL BATS OF THE AMERICAS
The Brooks Sink LF was collected from the Marks Head Formation exposed near the bottom of Brooks Sink, Bradford County, northern peninsular Florida. Although the Brooks Sink LF was collected from a sinkhole, it is not a paleokarst deposit, but instead was derived from nearshore marine sediments of the Marks Head Formation (Morgan and Pratt 1988). Marine vertebrates dominate the Brooks Sink LF, including 17 species sharks, rays, and bony fish, as well as the sirenian Metaxytherium and the small long-beaked dolphin Pomatodelphis. The Brooks Sink LF also contains a diverse sample of terrestrial and freshwater amphibians and reptiles, several species of large mammals, and a fairly rich fauna of small mammals. The Brooks Sink mammalian fauna includes (from Morgan and Pratt, 1988): the marsupial Herpetotherium, the talpid Scalopoides, the rodents Proheteromys, Mesogaulus, and Jimomys, and the horses Archaeohippus blackbergi and Merychippus gunteri, as well as several isolated teeth of a vespertilionid bat.
The mammalian fauna from Brooks Sink contains several taxa indicative of a late Hemingfordian age (He2, 17-18 Ma). The Brooks Sink LF compares most closely with the better known late Hemingfordian Midway LF from the Torreya Formation in the Florida Panhandle (Morgan and Pratt 1988; Bryant et al. 1992). Brooks Sink and Midway share the horses Merychippus gunteri and Archaeohippus blackbergi and the rodents Mesogaulus and Proheteromys floridanus. The joint occurrence of these four mammals is indicative of a late Hemingfordian age for the Brooks Sink LF.