ABSTRACT The purpose of this trip is to visit an internationally famous Quaternary vertebrate paleontology site, Friesenhahn Cave, on the eastern margin of the Edwards Plateau in the heart of the central Texas Hill Country. This site has a very long history of scientific investigations beginning in the early twentieth century and continuing today. The cave has produced the fossil remains of more than 50 vertebrate taxa, including amphibians, reptiles and mammals. However, the abundant remains of an extinct scimitar cat, Homotherium serum, including juvenile individuals along with hundreds of teeth, cranial, and postcranial elements of juvenile mammoths, Mammuthus cf. M. columbi, make it an especially unique site. Our visit to Friesenhahn Cave will focus on its physical setting, cave sediment stratigraphy, potential age and taphonomy as they relate to the adaptations of Homotherium in the late Pleistocene of central Texas and its relationship to its potential prey, juvenile mammoths. We will also discuss recent studies of the cave itself, and its protection for future investigations by Concordia College.

Abstract Using data from two palaeontological databases, MIOMAP and FAUNMAP (now linked as NEOMAP), we explore how late Quaternary species loss compared in large and small mammals by determining palaeospecies-area relationships (PSARs) at 19 temporal intervals ranging from c. 30 million to 500 years ago in 10 different biogeographical provinces in the USA. We found that mammalian diversity of both large and small mammals remained relatively stable from 30 million years ago up until both crashed near the Pleistocene–Holocene transition. The diversity crash had two components: the well-known megafaunal extinction that amounted to c. 21% of the pre-crash species, and collateral biodiversity loss due to biogeographical range reductions. Collateral loss resulted in large mammal diversity regionally falling an additional 6–31% above extinction loss, and small mammal diversity falling 16–51%, even though very few small mammals suffered extinction. These results imply that collateral losses due to biogeographical range adjustments may effectively double the regional diversity loss during an extinction event, substantially magnifying the ecological ramifications of the extinctions themselves. This is of interest in forecasting future ecological impacts of mammal extinctions, given that c. 8% of USA mammal species, and 22% of mammal species worldwide, are now considered ‘Threatened’ by the IUCN.

Abstract Environmental changes associated with the last deglaciation (Termination 1 in the marine record) had profound effects on the evolution of biotic communities in North America. Vertebrate species, especially mammals, are particularly sensitive proxies for these changes, so they provide excellent documentation of the climatic fluctuations of the late Quaternary. However, vertebrate communities are not tightly bound aggregates of species; rather, they are collections of species randomly distributed along environmental gradients (Whitakker, 1970). Consequently, environmental change will not illicit a response from the entire community, but instead each species will respond according to its own tolerances. The species composition of a community may therefore be constantly in flux, and significant environmental fluctuations may cause major biotic reorganizations. Modem communities are not direct analogues for past ones, but changes in the distribution, abundance, and clinal variation of individual species can provide invaluable information about past environments. The composition of Pleistocene mammalian communities, even if extinct taxa are excluded, was not the same as modern ones (Graham, 1985b). In fact, many late Pleistocene mammalian communities were composed of species that today are geographically allopatric and appear to be ecologically incompatible. Figure 1 shows the modem distribution of species occurring at the same level in Baker Bluff Cave, Sullivan County, Tennessee (Guilday and others, 1978). These communities have been referred to as disharmonious (Lundelius and others, 1983), but this does not mean that the organisms were not in harmony with prevailing Pleistocene environments. Quite the contrary, disharmonious biotas were apparently maintained by equable climates that have no modem analogues. By equable climates we mean ones with reduced seasonal temperature extremes as originally defined by Hibbard (1960). This definition does not equate with maritime climates as implied by Rhodes (1984, p. 33), nor “oceanic,” as discussed by Guthrie (1982, p. 323), although maritime climates can be equable. Because mean annual temperature has negligible influence on equability, it is possible to have both cold and warm equable climates. Also, mean annual temperatures for equable climates may be the same as means for cold or warm continental nonequable climates (Fig. 2).