LATE PLEISTOCENE VERTEBRATE FAUNA AND BAT GUANO DEPOSIT OF LATETERA CAVE, ARIZONA, USA

ABSTRACT:

La Tetera is a cave formed in the mid-late Paleozoic limestones of the Rincon Mountains of southern Arizona, USA. The cave was sealed since the late Pleistocene and preserves a small vertebrate fauna reflecting the Rancholabrean NAL- MA including two extinct large mammals, horse (Equus conversidens) and camel (Camelops hesternus), as well as an extinct vampire bat (Desmodus stocki). Additional recovered biotic remains include hackberry endocarps (Celtis), char- coal, and a harmonious assemblage of vertebrates including toad (Anaxyrus), tortoise (Gopherus), squamates (Helo- derma, Dipsosaurus, Phrynosoma, Uta or Urosaurus, Aspidoscelis, Sonora, Rhinocheilus, Masticophis or Coluber, and Crotalus), roadrunner (Geococcyx), wren (Salpinctes), owl (cf. Athene), heteromyid and cricetid rodents, rabbits, Myotis sp., and shrew. Further investigation will likely reveal additional biotic remains. Preservation of bone is relatively poor, probably due to as-yet-undetermined, corrosive geochemical processes. Fossils occur as isolated skeletal elements scattered sparsely in several areas of the small cave or those recovered by screening of unconsolidated cave floor sed- iments (in which Desmodus is the second most commonly recovered taxon, after toads). A large, stratified paleoguano deposit in one room provides the potential to recover ancient environmental DNA from the bats, their dietary sources, and autochthonous and allochthonous microorganisms. A sample of the guano deposit gave a calibrated radiocarbon age of 23.7 ka, confirming a late Pleistocene age for the deposit and placing it within late Wisconsinan full glacial time and within Marine Isotope Stage 2. The radioisotopic age(s) of the vertebrate fossils are unknown. Several of the fossil vertebrates reflect a desertscrub fauna similar to that of the region today, and may reflect a southwestern lowland refu- gium for arid-adapted biota during the late Pleistocene.