ABSTRACT The sedimentary deposits of the Hadar Formation at Dikika and the Mount Galili Formation at Galili preserve a wealth of paleoenvironmental and paleoclimatic records spanning the last 5.29 Ma. Stable carbon and oxygen isotopic compositions of herbivore tooth enamel were analyzed for more than 600 specimens of 15 different taxa from 10 stratigraphic intervals. The application of carbon and oxygen isotopes here aims principally at reconstructing shifts in the relative abundance of C4 grasses, and its implications for climate indicators including temperature, aridity, and seasonality. The full range of δ13Cenamel values throughout the Plio-Pleistocene signifies a wide range of foraging strategies by the fauna, which in turn reflects the mosaic of vegetation at Dikika and Galili. Estimates of ecosystem carbon isotope composition (δ13Cecosystem , which is given by average δ13Cenamel of each large vertebrate taxon weighted by the respective faunal abundance and the estimated daily biomass consumption) is used to asses shifts in the ecosystem-scale proportion of C3 and C4 vegetation. In the Plio-Pleistocene, the general paleoenvironmental conditions varied from wooded grassland to grasslands with the total amount of C4 grass cover on the landscape varying between 35% and 91%. Likewise, the paleohabitat reconstructions indicate the presence of grassland, wooded grassland, woodland habitats throughout the Pliocene and in Middle Pleistocene but the relative proportion of the habitats has changed substantially with time. Although this result agrees with the general trend towards more open grassland since the Late Miocene, a rebound of closed habitats and C3 resources from closed canopy woodlands or forests is evident in the middle Pliocene between 3.42 Ma and 3.24 Ma. These changes in the proportion of habitats could have affected the distribution and availability of preferred food resources and has an implication on the interaction of the animals on the paleolandscape and competition for resources. 18Oenamel values also show a wide range of variation within each stratigraphic member and through time. Temporal variation of δ13Cenamel values within a given taxon, as well as differences among sympatric taxa, document different aspects of the environment and climate, including changes in drinking water source, seasonality, and periods of strong evaporation. Estimated δ13Cmeteoric water based on the most 18O-depleted hippo tooth enamel, displays values of -1.94 / (VSMOW) and -5.24 / (VSMOW) in the Middle Pleistocene of Asbole and middle Pliocene of Galili, respectively. A major shift in the isotopic composition of water at ~ 3.0 Ma was accompanied by a 6.0 / increase from middle Pliocene to the present. While a +3.8 / shift from early to middle Pliocene was documented. The isotopic composition of meteoric water between 4.6 Ma and 4.38 Ma was most 18O-enriched compared to the rest of the Pliocene estimates. Likewise, an increase in the estimated δ13Cmeteoric water values was documented in the Awash Valley and elsewhere in East Africa, which indicate a regional climate change since the early Pliocene. An increase in the aridity, which is expressed as mean annual water deficit (i.e., the difference between potential evapotranspiration and mean annual precipitation) is also evident since the early Pliocene. These changes during the Pliocene in the region may in part be attributed to a regional decrease in the amount of precipitation and changes in the moisture source superimposed on global climate changes.

Over 7000 sq. km of salt and six Plio-Pleistocene biostratigraphic horizons were mapped in the East Breaks and Garden Banks areas using a 12,000 km grid of seismic data and all obtainable well data. Structure mapping of allochthonous Jurassic salt and the six horizons (Globoquadrina altispira, Lenticulina 1, Angulogerina B, Hyalinea B, Trimosina A, and Sangamon Fauna) and isopachs of the intervals between these horizons revealed notable lateral variations in the area underlain by salt, in the degree of salt deformation, and in the size and thickness of associated intraslope basins. East of 94.5° W salt structures occupy 40% of the area and exhibit complex shapes that suggest a high degree of salt deformation. West of 94.5° W salt structures occupy 11% of the area and consist mostly of structurally simple salt stocks. A zone of high-offset north-south trending faults mark the transition between these two areas. Isopach maps of the six Plio-Pleistocene intervals (from 2.9 Ma to the present) reveal major shifts in the rates and locations of sediment accumulation. From 2.9 to 1.0 Ma. sediment-accumulation rates averaged only 0.8-1.3 mm/y with a maximum rate of 2.7 mm/y. From 1.0 to 0.69 Ma. sediment-accumulation rates averaged 5.8 mm/y with a maximum rate of 11.6 mm/y. This interval correlates to sediments deposited between the extinctions of Hyalinea balthica and Trimosina denticulata and recorded a major period of sediment loading/salt withdrawal between 1.0-0.69 Ma. From the end of this time to the present, sediment -accumulation rates averaged 1.7-2.1 mm/y with a maximum rate measured at 6.2 mm/y. Increased sediment influx during 1.0-0.69 Ma coincides with a major third order sea level lowstand and was focused in central Garden Banks. The restriction of such dramatically increased accumulation rates to this area suggests that sediment influx was accompanied by large-scale salt withdrawal. The increase in accommodation space created by salt withdrawal appears to be the most important factor affecting accumulation rates. Salt structural styles found on the upper continental slope are transitional between those found on the lower slope and those on the shelf. The shelf is dominated by isolated, individual salt stocks (km²) surrounded by kilometer thick sedimentary sections. The lower slope is dominated by broad, laterally continuous, allochthonous salt sheets (10³ km²) with moderate to thin sediment cover. The upper slope contains both of these structural styles plus intermediate size (10-10² km²) salt ridges and massifs. Observations made during this study suggest that differential sediment loading is the mechanism causing the changes in structural style. A Loading/Dissection model is presented to explain the formation of the three primary salt structural styles, their genetic relationship, and their observed distribution. Differential loading has dissected large salt sheets into numerous smaller and irregularly shaped ridges and stocks (like those found on the upper slope). Salt found on the upper slope originated in the Jurassic Louann Formation, but is now surrounded by Pleistocene age sediments. To achieve this relationship, it appears that some Jurassic salt has undergone at least two cycles of sediment loading and consequent diapirism. Salt/sediment relationships suggest that virtually all of the mapped salt is allochthonous. Repetitive sediment loading and salt structural development has not been previously documented and represents a step beyond the limits of current salt structural models. / text

Genetic diversity is a fundamental attribute that contributes to a species evolutionary survival. In recent times, conservation managers have recognized the need to preserve genetic diversity of declining species, and have also acknowledged the utility of genetic markers for describing genetic and ecological relationships within and among populations. Information obtained from genetic studies can be used in conjunction with information on population demography, land use patterns and habitat distribution to develop effective management strategies for the conservation of species in decline. The wallum froglet, Crinia tinnula, is one of Australia's smallest habitat specialist anurans. In recent years there has been a dramatic decrease in population numbers of this species. The habitat to which C.tinnula is endemic ('wallum' habitat) is restricted to low coastal plains along the southeast Queensland and northern New South Wales coastline. As human populations in this region expanded, the coastal areas have undergone significant development and large areas of wallum habitat have been cleared. The effect has been to convert once largely continuous patches of coastal heathland in to a matrix of small habitat patches within an area undergoing rapid urban expansion. This study aimed to document levels and patterns of genetic diversity and to define the population structure of C.tinnula populations within southeast Queensland, with the objective of defining possible conservation management units for this species. Results from 12S and COI mitochondrial markers clearly showed that two distinct evolutionary lineages of C.tinnula are present within southeast Queensland. The high level of divergence between lineages and strict geographic partitioning suggests long term isolation of C.tinnula populations. It is hypothesized that ancestral C.tinnula populations were once confined to wallum habitat refugia during the Pliocene resulting in phylogeographic delineation of 'northern' and 'southern' C.tinnula clades. Populations within each geographic region show evidence of range contraction and expansion, with subsequent restricted gene flow. Levels of genetic diversity appear, largely, to be the product of historical associations rather than contemporary gene flow. A revision of the current systematics of C.tinnula is required to ensure that discrete population groups are recognized as distinct evolutionary lineages and will therefore be protected accordingly.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Anthropology, 2006. / Includes bibliographical references (leaves 263-281).

Abstract This thesis examines the Mid-Pliocene climatic extreme ca. three million years ago (Ma) which was the latest longtime warm period. It is an important topic because the climate back then was warmer compared with the present. The bipolar regions are studied because they represent the largest areas that control the global climate. This study is based on clay mineral research that may significantly improve our knowledge of the Mid-Pliocene climate when combined with other palaeoenvironmental data. The paleoclimatological objectives of this study were: 1) to investigate how clay minerals reflect the Mid-Pliocene Global Warmth event, 2) to study ice sheet development at high latitudes, especially in East-Antarctica, and the history of ice rafting and sea ice, especially in the Arctic Ocean. This thesis deals with the clay mineral distribution and compositional analysis of the Pliocene-aged marine sediment sequences provided by the Ocean Drilling Program (ODP). The first studied site, Site 1165, is located at the continental rise of Prydz Bay, East Antarctica, and the second studied site, Site 911, is located at the Yermak Plateau, north of Svalbard, in the Arctic Ocean. The Pliocene smectite clay minerals at Site 1165 were mainly derived from Antarctic continental sources and transported to the site primarly by bottom currents related to warm events during the last 5 Ma. The evidence obtained in this study shows that the East Antarctic ice sheet may have been a dynamic ice sheet during the past 5 Ma, especially during the Mid-Pliocene. The results from the Mid-Pliocene possibly suggest a general warming trend. Based on the composition of the heavy minerals and clay minerals, at Site 911, the Pliocene smectite clay minerals were mainly transported within sea ice by the Siberian branch of the Transpolar Drift. The results indicate a warming trend at approximately 3 Ma after which they indicate a shift back to glacial conditions. Based on this study, the Mid-Pliocene Global Warmth can be observed in both the Arctic and Antarctic regions.

The Pliocene, a geologic epoch spanning ~2.6-5.3 million years ago (Ma), was a period in Earth’s history where temperatures were several degrees warmer than today and atmospheric CO2 was close to modern levels, making it an analogue for future climate change. Following this interval, the planet’s climate shifted to the familiar glacial-interglacial cycles of the Pleistocene (~0-2.6 Ma), beginning with the development of extensive Northern Hemisphere ice sheets at ~2.7 Ma. In response to these changes through the Plio-Pleistocene, several components of the Earth System, particularly related to East Asia and the North Pacific Ocean, varied both temporally and spatially, further modifying regional and global climate through various feedbacks. In this thesis, I utilize a combination of geochemical proxies derived from North Pacific marine sediments as well as a regional climate model to better understand the evolution of the westerly winds, North Pacific Ocean circulation, and East Asian desert landscapes, across the last five million years. In Chapter 1, I reconstruct Pliocene dust fluxes at two different sites in the North Pacific using the constant flux proxy extraterrestrial 3He (3HeET), the first of such records in the Pliocene. Along with 3HeET-derived export productivity fluxes and sea surface temperatures from the westernmost core, I show that the Northern Hemisphere westerly winds, were shifted poleward and weaker during much of the warm Pliocene. Coinciding with the intensification of Northern Hemisphere Glaciation, the westerlies shifted equatorward and strengthened at ~2.7 Ma, and during subsequent glacial periods thereafter. Combining my dust flux record with others from different ocean basin, I find that these changes in the westerly winds were globally synchronous. Chapter 2, entitled “Pliocene Variability of Active Pacific Meridional Overturning Circulation: Reevaluating North Pacific Productivity and Redox Conditions from ~2.5-6 Ma”, presents additional 3HeET-based export productivity flux data, as well as redox element concentrations, from the central subarctic North Pacific through the Pliocene. The new records suggest elevated North Pacific export production during the interval spanning ~4-5.5 Ma, followed by a decrease in the mid-Pliocene (~3.5-4 Ma). Combining this new data with previously published records and modeling output, I provide additional evidence for an active Pacific meridional overturning circulation during the warmer-than-present Pliocene, and add constraints on its variability under various climatic conditions. In Chapter 3, I bring together two constant flux proxy-derived dust flux datasets from the same core in the western North Pacific Ocean to provide novel insight into Quaternary dust dynamics in East Asia. By utilizing constant flux proxies, and accounting for inputs of volcanic material, I show for the first time that dust input to the North Pacific decreased over the last ~2.7 Myr, particularly during glacial periods. While quite different from other previously published dust datasets, this finding is consistent with our current understanding of East Asian dust production mechanisms, and acts as a strong impetus to perform more comprehensive studies of dust fluxes to the North Pacific and other depositional areas downwind of arid regions. Chapter 4 transitions to a terrestrial setting, in which I investigate the impacts of shifting arid region surface albedo on the atmospheric boundary layer using the Hami Basin, China, as a test location. Combining new simulations from the Weather Research and Forecasting base model and available geologic data, I report a previously undescribed “wind-albedo-wind” feedback process. Specifically, I propose that wind erosion, in conjunction with surficial sediments of various albedos, leads to altered wind speeds, and eventually fluctuations in erosion itself. In Chapter 5, I expand upon the work in the preceding chapter by coupling the Weather Research and Forecasting model with a chemistry component to simulate dust emissions. In addition, along with albedo, I characterize previously interpreted surface changes through time to reflect shifts in erodibility and surface roughness. I conclude that although albedo does ultimately influence near-surface wind speeds and dust emissions as predicted in my earlier study, the effects of variable surface roughness and erodibility dominate. Integrating these results with an updated interpretation of the geologic evolution of the Hami Basin, we find that during various periods of the last ~700 ky, the Hami Basin, and likely the greater stony Gobi Desert, could have been much more important dust sources than today.

Many organisms are known to reach high levels of endemism and biodiversity in the temperate forests of Southern Appalachia, especially in the dense forests and rugged terrain of the Blue Ridge physiographic province. Many plants and fungi reach their highest levels of biodiversity in these mountains, as does one group of vertebrates: the lungless salamanders, Plethodontidae. This family of salamanders hosts the most species of any other group of salamanders on earth and has adapted to a wide range of habitats. Only two of the approximately twenty-seven known genera are not found in North or South America, and while we know much about the modern-day biology of this family, few fossils older than ~15,000 years have been recovered, complicating our understanding of the historical distribution of this group and the timing of key evolutionary events within the family. Recently discovered salamander fossils from the Gray Fossil Site provide the foundation of this project. We describe these exceptionally large plethodontid remains to a new genus that belongs to the group containing dusky salamanders, or desmognathans. The morphology of the fossil material resembles Phaeognathus hubrichti, an extant burrowing species from southern Alabama with a suite of primitive characteristics. Comparison of the fossil material to modern desmognathans using geometric statistical methods has revealed that the extinct form was likely similar in lifestyle to P. hubrichti, but considerably larger. It was unparalleled in the southern Appalachians in terms of size and ecology, and reveals a more complex evolutionary history for desmognathan salamanders.

The Gray Fossil Site in northeastern Tennessee preserves materials from a 5-million-year-old ecosystem, including wood from nearby trees. This study consists of three parts: conservation of wood remains, identification of taxonomic groups represented by the fossil wood, and measuring the organic content of fossil wood from the Gray Fossil Site. When excavated, wood specimens from the site are saturated due to a high local water table. After testing seven different techniques to dry wood specimens, wrapping a specimen in string and allowing it to dry slowly was the method least likely to cause warping and cracking. Microscopic examination of wood cross sections reveal tree rings with distinct anatomical features, with implications for taxonomic identification. Tentatively identified taxa that are present at the Gray Fossil Site are similar to those present in pre-modern forests of northeastern Tennessee. Finally, loss on ignition tests indicate that the Gray Fossil Site wood lacks extensive permineralization or mineral replacement. The presence of alpha-cellulose, albeit stained with iron oxides, illustrates the potential for future stable isotope analyses.

Climate change during the Quaternary played an important role in the distribution of extant plants. Herein, cone scales of Cedrus (Pinaceae) were uncovered from the Upper Pliocene Sanying Formation, Longmen Village, Yongping County of Yunnan Province in southwestern China. Detailed comparisons show that these fossils all belong to the genus Cedrus (Pinaceae), and a new species is proposed, Cedrus angusta sp. nov. This find expands the known distribution of Cedrus during the Late Pliocene to Yunnan, where the genus no longer exists in natural forests. Based on the analysis of reconstructed Neogene climate data, we suggest that the intensification of the East Asian winter monsoon during the Quaternary may have dramatically increased seasonality and given rise to a much drier winter in Yunnan. Combined with information on Cedrus fossil records and its seed physiology, we conclude that the intensification of a drier climate after the Late Pliocene may have prevented the survival of Cedrus seedlings, leading to the eventual disappearance of Cedrus in western Yunnan. This study indicates that the topography in southwestern China acted as a vital refuge for many plants during the Quaternary, but that other species gradually disappeared due to the intensification of the monsoonal climate.

Climate change during the Quaternary played an important role in the distribution of extant plants. Herein, cone scales of Cedrus (Pinaceae) were uncovered from the Upper Pliocene Sanying Formation, Longmen Village, Yongping County of Yunnan Province in southwestern China. Detailed comparisons show that these fossils all belong to the genus Cedrus (Pinaceae), and a new species is proposed, Cedrus angusta sp. nov. This find expands the known distribution of Cedrus during the Late Pliocene to Yunnan, where the genus no longer exists in natural forests. Based on the analysis of reconstructed Neogene climate data, we suggest that the intensification of the East Asian winter monsoon during the Quaternary may have dramatically increased seasonality and given rise to a much drier winter in Yunnan. Combined with information on Cedrus fossil records and its seed physiology, we conclude that the intensification of a drier climate after the Late Pliocene may have prevented the survival of Cedrus seedlings, leading to the eventual disappearance of Cedrus in western Yunnan. This study indicates that the topography in southwestern China acted as a vital refuge for many plants during the Quaternary, but that other species gradually disappeared due to the intensification of the monsoonal climate.