Terminal Pleistocene and Holocene mammal remains from Bogus Cave, Jones County, Iowa

A paleontological excavation in Bogus Cave, Jones County, east-central Iowa, yielded a rich and diverse collection of terminal Pleistocene and Holocene vertebrate remains. Nearly a cubic meter of matrix was excavated from stratified deposits in a constricted passage approximately 35 m from the mouth of the cave. The 9,363 mammalian cranial and dental specimens identified from this excavation represent a minimum of 772 individuals and at least 46 extant species, nine of which no longer occur in the area. Most of the recovered skeletal material is derived from the scats and meals of raccoons and other small mammalian carnivores.; The upper bone assemblage contains primarily late Holocene material, but also includes earlier Holocene and terminal Pleistocene remains. All of the abundant mammalian taxa in this assemblage currently inhabit Jones County including the northern short-tailed shrew (Blarina brevicauda), plains pocket gopher (Geomys bursarius), prairie vole ( Microtus ochrogaster), and woodland vole (Microtus pinetorum ). Many species in the upper assemblage do not live together at present and some have ranges separated by more than 1,000 km. Most of these non-analog associations likely originated from the mixing of Pleistocene and Holocene elements.; The lower bone assemblage, dated to 10,069 ± 70 and 10,852 ± 70 yr B.P., is considered a terminal Pleistocene deposit. Species with northern affinities, including several that no longer occur in the Midwest, dominate the terminal Pleistocene mammalian fauna. In particular, the northern pocket gopher (Thomomys talpoides), meadow vole (Microtus pennsylvanicus), and yellow-cheeked vole (Microtus xanthognathus ) are especially well represented. The non-analog associations in the lower assemblage appear to reflect communities fundamentally different from those in existence today.; The composition of the lower mammalian fauna indicates that a mixed conifer-hardwood forest interspersed with patches of grassland covered east-central Iowa at the end of the Pleistocene. Additionally, the mammalian proxy data from the terminal Pleistocene suggest mean July temperatures were conservatively 6°C cooler than at present and that the local moisture regime was at least 25% drier.