The Great American Biotic Interchange is considered to be a punctuated process, primarily occurring during four major pulses that began approximately 2.5 Ma. Central America and southeastern Mexico have a poor fossil record of this dynamic faunal history due to tropical climates. Exploration of submerged caves in the Yucatán, particularly the natural trap Hoyo Negro, is exposing a rich and remarkably well-preserved late Pleistocene fauna. Radiometric dates on megafauna range from approximately 38 400-12 850 cal BP, and extinct species include the ursid Arctotherium wingei and canid Protocyon troglodytes. Both genera were previously thought to be indigenous to and confined to South America and appear to represent an instance of large placental mammals, descended from North American progenitors, migrating back north across the Panama Isthmus. This discovery expands the distribution of these carnivorans greater than 2000 km outside South America. Their presence along with a diverse sloth assemblage suggests a more complex history of these organisms in Middle America. We suggest that landscape and ecological changes caused by latest Pleistocene glaciation supported an interchange pulse that included A. wingei, P. troglodytes and Homo sapiens.

This study presents an analysis of the zooarchaeological remains from Klissoura Cave 1, a Middle Paleolithic through Mesolithic site in Peloponnese, Greece. Changes in subsistence patterns are evaluated across a long sequence (ca. 80,000-10,000 BP) against a backdrop of environmental change. Results are interpreted using models from evolutionary ecology, specifically prey choice, central place foraging, and patch choice models. Two major trends are apparent in the series. One is a decline in the exploitation of high-ranked ungulate species with an overall increase in lower-ranked small game animals. The second is an increase in low-ranked small, fast-fast moving animals (e.g., hares and partridges) at the expense of higher-ranked small, slow-moving animals (e.g., tortoises). These changes cannot be accounted for by environmental shifts alone, though shifts in ungulate diversity likely track the expansion and contraction of plant communities. The increase in use of low-ranked prey indicates human population growth and demographic pressure in southern Greece during the late Pleistocene and early Holocene. In addition to these overarching trends, there are changes in site use during the sequence. In the Middle Paleolithic, foragers used Klissoura Cave 1 more during the winter and overwhelmingly hunted prime-aged adult animals, maternal herds of fallow deer in particular. In the Upper Paleolithic and later periods, the site continued to be used during the winter, in addition to other times of year, but the mortality profiles reflect a natural fallow deer herd structure. There was an intense period of occupation during the Aurignacian period. This is evidenced by numerous clay-lined hearth features, a possible rock-lined structure, and increases in ornaments, as well as abundant lithic and faunal materials. The ungulate faunas are particularly rich during this period, but there is evidence of resource intensification based on increased bone marrow processing and the transport of marrow-rich elements to the site. After this period there was a gradual decline in site use through the end of the Upper Paleolithic and into the Mesolithic, though the exploitation of low-ranked resources (e.g., small, fast-moving game) indicates that populations were on the rise in there region as a whole.

No description available.

The continental margin in the area west of Shetland was subjected to repeated and extensive ice sheet advances during the Late Pleistocene. Seabed imagery, seismic survey and borehole core data show the Late Devensian ice sheets expanded across the continental shelf three times, two of these advances reaching the shelf edge. On the inner shelf, where present-day water depths are generally less than 100m, only thin sediments from the last retreat phase and exposed rock surfaces remain, all other deposits from earlier phases having been removed by the last advance. On the mid to outer shelf elements of all three phases are preserved, including lodgement and deformation tills, melt-out and water-lain till sheets, in-filled hollows left by stagnant ice decaying in situ and a series of large recessional and terminal moraines. In addition, there is evidence of shallow troughs and overdeepend basins which indicate preferential ice-drainage pathways across the shelf which were formerly occupied by ice streams. At the shelf edge, a thick wedge of glacigenic sediment forms a transition from the till sheets and moraines of the shelf to debris flows composed of glacigenic sediments on the upper slope. Shelf-edge moraines show an architecture indicating floating ice in modern water depths over approximately 180m, suggesting the West Shetland ice sheet was no more than about 250m thick. The upper and middle slope is dominated by glacigenic debris flows which are focused in the slope areas below the proposed ice stream discharges at the shelf edge. The mid-to-lower slope has been subjected to contour current activity which has re-worked much of the glacigenic sediment in this position. The lower slope and floor of the Faroe-Shetland Channel are marked by either large debris flow lobes of glacigenic sediment or thin glacimarine muds deposited from suspension. A conceptual model of the glacigenic development of a passive continental margin based upon the West Shetland example shows the deposited sequence for both advance and retreat phases of a glacial cycle, and the actual preserved sequence which might be expected in the rock record. The model also shows that ice sheet buoyancy, thickness, and to a lesser extent, basin subsidence, are the most important factors in the deposition and preservation of a glacially-influenced marine sequence.

This thesis documents Agate Basin archaeological remains in the provinces of Alberta and Saskatchewan. By extension, it examines the context of the rapidly changing Late Pleistocene/Early Holocene environment. A database of information on Agate Basin sites in the study area is assembled. Site analysis allowed for the examination of Agate Basin adaptations based on radiocarbon chronology, landform use, mobility, resource use, projectile point production and climate and environmental context. The results confirm that Agate Basin producing peoples within Alberta and Saskatchewan displayed variability concerning projectile point production, landscape use, resource extraction, and hunting practice. It appears that Agate Basin producing people within Alberta and Saskatchewan practiced a predominantly broad-based strategy for procuring resources. No evidence exists to support a model of large-scale communal hunting. Likely, the strongest influence on the particular adaptive behaviours of Agate Basin producing people in Alberta and Saskatchewan can be summarized as environmental.

Although five genera of procyonids are currently present in South America, only two of the extant genera, Procyon and Nasua are represented in the South American fossil record. A recent discovery of a procyonid lower second molar in Late Pleistocene deposits of Aurora do Tocantins, northern Brazil, offers potential to further our understanding of the stratigraphic and temporal range of South American fossil procyonids. We use geometric morphometric analysis of two-dimensional landmarks and semilandmarks to explore morphological variation in the lower second molars of extant Procyon lotor and Procyon cancrivorus and multivariate methods to support the identification of the Pleistocene specimen as P. cancrivorus. This material represents the second fossil record of P. cancrivorus in South America Procyonids entered South America in two phases: the first comprising by Cyonasua and Chapadmalania during the Late Miocene, and the other recent genera, beginning in the Late Pleistocene. These Late Miocene procyonids were more carnivorous than Late Pleistocene-Recent omnivorous taxa and possible went extinct due to competition with other placental carnivorans that entered South America and diversified during the latest Pliocene-Early Pleistocene.

Brazilian late Pleistocene snakes have an extensive fossil record and are recognized for southern, northeastern and northern regions of this country. This fossil record is represented by the families Boidae, 'Colubridae', Viperidae and Elapidae. Here is presented the first record for Eunectes Wagler for the late Pleistocene of the Brazilian northern region. The material described is a single incomplete dorsal vertebra, and although it shares several vertebral features with most Boidae taxa, it can be distinguished from all other boids because is a robust and wide vertebra with a slightly depressed neural arch, relatively thick and robust zygosphene with a prominent median turbercle. The taxonomic allocation to E. murinus (Linnaeus) is based on the exceptionally large size of the vertebra. The discovery of E. murinus in the late Pleistocene of Tocantins State indicates the presence of a large body of water in a region that has previously been interpreted as relatively arid during this time.

Although five genera of procyonids are currently present in South America, only two of the extant genera, Procyon and Nasua are represented in the South American fossil record. A recent discovery of a procyonid lower second molar in Late Pleistocene deposits of Aurora do Tocantins, northern Brazil, offers potential to further our understanding of the stratigraphic and temporal range of South American fossil procyonids. We use geometric morphometric analysis of two-dimensional landmarks and semilandmarks to explore morphological variation in the lower second molars of extant Procyon lotor and Procyon cancrivorus and multivariate methods to support the identification of the Pleistocene specimen as P. cancrivorus. This material represents the second fossil record of P. cancrivorus in South America Procyonids entered South America in two phases: the first comprising by Cyonasua and Chapadmalania during the Late Miocene, and the other recent genera, beginning in the Late Pleistocene. These Late Miocene procyonids were more carnivorous than Late Pleistocene-Recent omnivorous taxa and possible went extinct due to competition with other placental carnivorans that entered South America and diversified during the latest Pliocene-Early Pleistocene.

Brazilian late Pleistocene snakes have an extensive fossil record and are recognized for southern, northeastern and northern regions of this country. This fossil record is represented by the families Boidae, 'Colubridae', Viperidae and Elapidae. Here is presented the first record for Eunectes Wagler for the late Pleistocene of the Brazilian northern region. The material described is a single incomplete dorsal vertebra, and although it shares several vertebral features with most Boidae taxa, it can be distinguished from all other boids because is a robust and wide vertebra with a slightly depressed neural arch, relatively thick and robust zygosphene with a prominent median turbercle. The taxonomic allocation to E. murinus (Linnaeus) is based on the exceptionally large size of the vertebra. The discovery of E. murinus in the late Pleistocene of Tocantins State indicates the presence of a large body of water in a region that has previously been interpreted as relatively arid during this time.

The small number and diffuse distribution of sites with intact Late Pleistocene/Early Holocene occupations in the Southeastern United States consequently makes examining Late Pleistocene/Early Holocene settlement patterning in the region difficult (Goodyear 1999). The Hester Site (22MO569), located in northeastern Mississippi, contains intact Late Pleistocene/Early Holocene deposits that can potentially afford archaeologists with a better understanding of late Pleistocene/early Holocene settlement in the region (Brookes 1979; Goodyear 1999:463-465). Investigations at Hester by Brookes (1979) revealed a stratified site containing artifacts that represented the late Paleoindian through Woodland periods in the Southeastern United States. Burris (2006) developed an alternative typology by re-analyzing the Hester biface assemblage, which demonstrated four discrete occupations at the Hester site. I use formation theory to evaluate the degree to which post-depositional processes have impacted the deposits at the Hester site. I have determined that the Hester site has not been significantly altered by post-depositional processes.