Browsing by Subject "Taphonomy"
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Item Insights into the microbial degradation of bones from the marine vertebrate fossil record: an experimental approach using interdiciplinary analyses(2014-08) Vietti, Laura AnnResearchers rely on the fossil record to understand and predict changes in faunal composition and evolutionary trends associated with climatic change. However, taphonomic processes such as scavenging, transport, and weathering, significantly influence the type and quality of information preserved in the fossil record by filtering and diminishing the fidelity of ecological data. To help account for taphonomic biasing, I developed a series of interdisciplinary approaches to better understand the role and characterization of microbes during the fossilization of vertebrate remains, and an additional study that improves a well-established method for estimating time averaging of fossil bone accumulations. To better understand which bacteria are responsible for bone decay, I simulated aspects of natural whale-falls by adding defleshed bones to mesocosms made of natural marine mud and water. Sequencing the V3 region of the 16S rRNA taxonomic identifier gene of bone-associated microbial communities indicated that the dominant bacterial groups exploiting bone nutrients were taxa within the Alphaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and Epsilonproteobacteria, as well as Bacteroidetes and Firmicutes. Relative abundances of these bacterial groups changed throughout the experiment, reflecting four community successions. Sulfidic framboids were observed on the experiment bone surfaces within one week and were interpreted to form as the result of reducing conditions within a dark-colored microbial mat overlain by oxic waters. When compared with published sedimentary framboid populations, the bone-hosted framboids were most similar to framboids formed in anoxic water-columns, even though the bone was overlain by oxygenated conditions, suggesting that the growing periods for framboids are shorter on bone surfaces than those in sediments and do not reflect geochemical conditions. Bone surface texture is known to degrade in a predictable fashion due to subaerial exposure, and can thus act as a proxy for estimating post-death/ pre-burial time since death which is relevant for assessing time averaging. In the final dissertation chapter I show that traditional weathering analyses can be characterized using quantitative textural analyses from 3D scans of bone surfaces. Quantifying bone weathering analyses may enable more reliable comparative taphonomic analyses by reducing inter-observer variations and by providing numerical data compatible for use in multivariate statistics.Item Multivariate DNA taphonomy: evaluating the effects of environmental context, specimen properties, and laboratory strategies on the preservation and detection of DNA in ancient and challenging specimens.(2012-05) Alveshere, Andrea JoannaWithin their diminutive structures, DNA molecules hold tantalizing potential to address myriad questions about human history, prehistory, and the evolution and dispersal of all forms of life. When accessible and accurate, DNA from ancient and degraded specimens can elucidate many topics of interest to researchers in a variety of fields including archaeology, biological anthropology, forensics, conservation and evolutionary biology, agronomy, and medicine. Despite the great informational potential of genetic studies, the high cost and destructive nature of DNA analyses discourage many researchers from submitting archaeological specimens for testing. A diversity of DNA detection protocols, the limited scope of individual research projects, and a bias toward publishing successful results make it difficult to evaluate the comparative influence of different preservation factors, field methods, and laboratory strategies on the recovery of useful genetic information from ancient and degraded specimens. The work presented in this manuscript is predicated upon the contention that the opportunity to conduct ancient DNA research entails an obligation to make the most of every specimen fragment consumed, every data point collected, and every funding dollar spent. The scope of this project is to develop a system for evaluating whether DNA testing might be appropriate for a given specimen; for determining which steps can be taken to increase the chances of recovering useful data; and for maximizing the contribution of individual research projects, conducted across disparate fields, to the greater body of knowledge on DNA preservation and detection. This endeavor involved: (1) inventorying variables having potential to influence DNA preservation and/or detection; (2) investigating subsets of the candidate variables through case studies of archaeological materials from Kromdraai, Wonderwerk Cave, and Border Cave, South Africa, Silvernale Village, Minnesota, and UV-irradiated forensic-type samples; and (3) the development and validation (via case study data) of the Biomolecular Preservation and Detection Information System (BIOPADIS™), a standardized system for synthesis, management, and analysis of biomolecular taphonomy data. BIOPADIS™ (\bī-’op-ad-is\) comprises a relational database that accommodates all manner of relevant data, a querying capability that makes these data accessible, and a set of statistical approaches appropriate for identifying and evaluating correlations within these multivariate, multi-study data.Item Small Mammal Taphonomy and Utilization by Middle Stone Age Humans in the Cape Floristic Region of South Africa(2015-11) Armstrong, AaronThough evidence for the creation and use of symbols and for technological and social complexity have emerged from the Cape Floristic Region of South Africa (CFR) that date to the Middle Stone Age (MSA), 285 – 30 thousand years ago, the relationship between these factors and the foraging strategies and use of landscapes by MSA humans remains anomalous, particularly in relation to small mammals (<4.5 kg adult body weight) and size 1 bovids (<20 kg adult body weight). This study is a taphonomic assessment which centers on the role of small mammals in the resource base of humans during the MSA and ─ together with large mammal, tortoise, and shellfish ─ provides a more complete understanding of the range of human subsistence strategies and foraging adaptations employed in the CFR during the MSA. Data were collected and analyzed from two MSA CFR fossil bone assemblages, Die Kelders Cave 1 (DK1) and Pinnacle Point site 5-6 (PP5-6). This study includes the small mammal and size class 1 bovid archaeofaunas from DK1 and PP5-6 and provides detailed taphonomic analyses of their remains in order to evaluate the degree to which humans, raptors, and mammalian carnivores were involved in their accumulation at these sites. In addition to the archaeological collections, actualistic control assemblages of known human, raptor (diurnal and nocturnal), and mammalian carnivore accumulation were specifically created and analyzed for this project. These control assemblages broaden the scope of accessible small mammal assemblage by featuring diverse prey mammals of different sizes and builds as well as a variety of typical small mammal predators. Analyses of the DK1 and PP5-6 small mammal archaeofaunas include a detailed evaluation of human, raptor, and mammalian carnivore bone surface modification frequencies and bone breakage patterns. In addition, comprehensive comparisons with the control assemblages of known accumulation were conducted in order to better understand the degrees to which humans, raptors, or mammalian carnivores contributed to the small mammal faunas at DK1 and PP5-6. DK1 humans maximized the environmental yield by exploiting low-quality resources as evidenced by numerous cut-marked and burned small mammal fossils. This strategy may have been employed in response to localized environmental conditions and to greater human population densities. The humans who occupied PP5-6 did not exploit small mammals and instead focused on higher-quality resources like shellfish and large ungulates. Humans and predators did not accumulate small mammals in any substantial way at PP5-6, suggesting that these taxa may have been less abundant near the site and/or that humans could afford to concentrate exclusively on high-quality resources, perhaps because of a higher-yield local environment. Results of this study suggest that an adaptive response by humans to the environmental conditions of MIS4 was to maximize the resource yield of local habitats to include lower-quality resources when necessary. The incorporation of these resources in the face of changing environmental and population pressures is a subsistence adaptation that has not been documented in the previous glacial phase of MIS6 and may have played a crucial role in the population stability and expansion evidenced by the substantial number of sites in the Cape dating to MIS4.Item Spatial approaches to site formation and carnivore-hominin interaction at Dmanisi, Georgia(2016-06) Coil, ReedSpatial analyses are valuable tools for examining abiotic and biotic site formation processes that contribute to the accumulation of archaeological and paleontological material. When these analyses are used in tandem with taphonomic and geologic interpretations, archaeologists can make stronger arguments for site reconstruction and behavioral inferences. Spatial analyses have been used for decades to understand how human behaviors and the deposition of material are linked. Similarly, spatial behaviors by carnivores are apparent, with some species, namely hyenas, differentially using space for various behaviors. Through the lens of spatial analysis, this dissertation examines the degree to which abiotic and biotic agents contributed to site formation at the Early Homo site of Dmanisi, Georgia. Taphonomic and geologic studies at Dmanisi have interpreted the hominin-bearing deposits in Block 2 as resulting primarily from biotic agents, mainly carnivores, and not from fluvial or colluvial action (Lordkipanidze et al., 2006, 2007; Tappen et al., 2007). This dissertation expands on these interpretations by providing spatial evidence from two excavation areas (M6 and Block 2) and multiple strata used in conjunction with taphonomic analyses by Martha Tappen and geologic and archaeological analyses by Reid Ferring to compare relatively horizontal strata to the complex pipe/gully fill strata in which the highest concentration of bones are found. Orientation and dip, fragmentation and winnowing, and skeletal refits are examined and the results for each support the interpretation that the assemblages are not a product of fluvial and colluvial deposition. What is more, an analysis of spatial patterning indicates that higher densities of carnivores are located in the pipe/gully fill deposits than elsewhere. Also, coprolites are prevalent in these deposits, but follow a different spatial distribution than the skeletal material. Taphonomic analyses demonstrate that carnivores contributed greatly to the consumption of carcasses, and several species of carnivores are present at Dmanisi during this time. Each species of hyena has been observed to defecate in specific areas, both inside of the dens and outside in latrines, which could explain the cluster of coprolites in the B1 strata in Block 2. Two of the pipe/gully fill phases of B1 (B1x and B1y) are within a complex basalt formation that could have provided a secluded area for carnivores to consume carcasses and potentially have dens. These coprolites provide potential insight into carnivore space use in the Early Pleistocene, but further analysis is necessary to attribute the coprolites to specific animals. In any case, carnivores appear to be the main influence on site formation at Dmanisi, while the hominin imprint is minimal. In order to understand the potential carnivore-hominin interaction and the timing of carcass access at Dmanisi, this dissertation also provides new analytical methodology for studying bone fracture angles produced during the marrow acquisition process. In lieu of agent-specific surface modifications (i.e. carnivore tooth marks or hammerstone percussion marks), green breaks on long bones are difficult to attribute to a specific agent of breakage. By quantifying fracture angles, perhaps archaeologists can infer the causal agent of breakage and interpret the influence of carnivores and hominins on bone breakage. This dissertation contributes the results of a controlled breakage experiment where bones were broken by hyenas and hammerstones. Based on the results of the fracture angle analysis, different long bones create different fracture angle assemblages and it is necessary to identify the long bone fragments to at least limb portion (upper, middle, lower) if not to skeletal element. In addition, the preliminary results of the hyena created assemblage shows that hyena broken bones result in fracture angles further from 90° than hammerstone broken bones. Carnivores played an important role in the accumulation of faunal material at Dmanisi, Georgia. Evidence for abiotic site formation processes, such as fluvial and colluvial deposition, is minimal and likely did not affect the original depositional context of the stones and faunal material. The hominin contribution to site formation is also minimal, but perhaps understanding fracture angles created during the marrow acquisition process can allow for further testing of this hypothesis in the context of Early Homo. By examining these different factors, this dissertation broadens the knowledge of how carnivores and hominins contributed to site formation during the earliest expansion of our genus outside of Africa.Item Taphonomy on Rusinga Island, Kenya(2018-08) Jenkins, KirstenUnderstanding taphonomy and site formation processes for fossil human and primate sites is central to testing hypotheses about paleoenvironments and the natural selection of various traits and behaviors in our lineage. Strong inferences about paleoenvironmental and behavioral reconstructions, however, rest on demonstrated associations between both fossil and sedimentary environmental proxies and taphonomic actualistic data. On Rusinga Island, Kenya, Miocene and Pleistocene fossils have been collected and studied for a century, yielding a rich assemblage of early Miocene stem hominoids and catarrhines—Ekembo, Dendropithecus, Limnopithecus, Rangwapithecus, and Nyanzapithecus. Numerous mammalian, avian, reptilian, invertebrate, and plant fossils are preserved alongside these primates. Pleistocene fossils on Rusinga are often in association with Middle Stone Age tools made my early Modern Humans. Despite the long history of collection, little consensus has been reached about the paleoenvironmental contexts in Miocene Rusinga, in part due to faunal mixing and lack of broad taphonomic studies. Furthermore, behavioral reconstructions of have been limited by not engaging with taphonomic surface modification data. Pleistocene deposits are generally understudied compared to the Miocene fossils and behavioral reconstructions have been similarly limited. This dissertation examines taphonomic site formation processes of both time periods using archaeological style excavations, systematic surface collections and taphonomic data collection. Bonebed excavations and taphonomic data at Miocene R5-Kaswanga inform paleoenvironmental reconstructions and show that attritional predation and fluvial processes account for most of the bone accumulations. A survey of Miocene primate remains for trends in surface modifications suggest predation by creodonts, carnivores and avian raptors, indicating important selection pressures from predators. Bonebed excavations at Pleistocene Wakondo yield the first behavioral reconstruction of tactical hunting on Rusinga Island.