Within this dissertation, I document how—and hypothesize why—the quirks and qualities of the Cambrian Period demarcate this interval as fundamentally different from the preceding Proterozoic Eon and succeeding periods of the Phanerozoic Eon. To begin, I focus on the anomalous marine deposition of the mineral apatite. Sedimentary sequestration of phosphorus modulates the capacity for marine primary productivity and, thus, the redox state of the Earth system. Moreover, sedimentary apatite minerals may entomb and replicate skeletal and soft-tissue organisms, creating key aspects of the fossil record from which paleontologists deduce the trajectory of animal evolution. I ask what geochemical redox regime promoted the delivery of phosphorus to Cambrian seafloors and conclude that, for the case of the Thorntonia Limestone, apatite nucleation occurred under anoxic, ferruginous subsurface water masses. Moreover, I infer that phosphorus bound to iron minerals precipitated from the water column and organic-bound phosphorus were both important sources of phosphorus to the seafloor. Petrographic observations allow me to reconstruct the early diagenetic pathways that decoupled phosphorus from these delivery shuttles and promoted the precipitation of apatite within the skeletons of small animals. Together, mechanistic understandings of phosphorus delivery to, and retention within, seafloor sediment allow us to constrain hypotheses for the fleeting occurrence of widespread apatite deposition and exquisite fossil preservation within Cambrian sedimentary successions. Next, I describe and quantify the nature of carbonate production on a marine platform deposited at the hypothesized peak of Cambrian skeletal carbonate production. I find that fossils represent conspicuous, but volumetrically subordinate components of early Cambrian carbonate reef ecosystems and that despite the evolution of mineralized skeletons, Cambrian carbonate platforms appear similar to their Neoproterozoic counterparts, primarily reflecting abiotic and microbial deposition. Finally, I investigate the geodynamic mechanism responsible for rapid, oscillatory true polar wander (TPW) events proposed for the Neoproterozoic and Phanerozoic Earth on the basis of paleomagnetic data. Using geodynamic models, I demonstrate that elastic strength in the lithosphere and stable excess ellipticity of Earth’s figure provided sufficient stabilization to return the pole to its original state subsequent to convectively-driven TPW. / Earth and Planetary Sciences

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Human bone is considered one of the most direct and insightful sources of information on peoples of the past. As a result, curation protocols have been developed to ensure that the integrity of human skeletal collections is maintained. Although collections are generally considered safe when these protocols are followed, the results of this investigation show that the Tell Leilan skeletal collection from Syria (circa 2900 – 1900 BCE) was contaminated by microbial growth (also known as biodeterioration) during curation. This biodeterioration was evaluated by light microscopy (LM), by the application of a histological preservation index (HPI), and by scanning electron microscopy (SEM). All samples (n=192) were found to be biodeteriorated by LM and the HPI. SEM confirmed that the Tell Leilan skeletal material had been contaminated by a complex microbial aggregate known as a biofilm. Amycolatopsis sp. and Penicillium chrysogenum, along with species of Aspergillus, Chaetomium, and Cladosporium were isolated and cultured from several contaminated bones and were identified based on morphology and DNA sequences. The results of this research suggest that we must focus on new techniques to examine bone as well as on new conservation protocols designed to limit the growth of biofilms in human skeletal collections in the future.

The investigation of mass graves involves aspects of high political, judicial, and emotional impact. Understanding how bodies held within mass graves change between the time they are deposited and the time they are discovered (the realm of forensic taphonomy) is vital for competent collection of evidence and accurate evaluation of the scene. This thesis explores these issues by detailing experimental research undertaken to better understand the affects of environmental factors on low-density, orderly placement mass graves. Issues pertaining to how decomposition of bodies in contact differs from that of single bodies, intentional disturbance, and temperature change were examined experimentally using pigs as human analogues over a period of almost one year outside of Edmonton, Canada. There are three primary avenues in which the information obtained can be applied to the real world: estimation of elapsed time since death, planning mass grave investigations and reducing evidence loss, and evaluating post-burial disturbance or intentional vandalism.

Several late Pleistocene fossil localities in the Kings Creek catchment, Darling Downs, southeastern Queensland, Australia, were examined in detail to establish an accurate, dated palaeoecological record for the region, and to test human versus climate change megafauna extinction hypotheses. Accelerator Mass Spectrometry (AMS 14C) and U/Th dating confirm that the deposits are late Pleistocene in age, but the dates obtained from the two methods are not in agreement. Fluvial depositional accumulation processes in the catchment reflect both high-energy channel and low-energy episodic overbank deposition. The most striking taphonomic observations for vertebrates in the deposits include: 1) low representation of post-cranial elements; 2) high degree of bone breakage; 3) variable abrasion but most identifiable bone elements with low to moderate degree of abrasion; 4) low rates of bone weathering; 5) low degree of carnivore bone modification; and 6) low degree of articulated or associated specimens. Collectively, those data suggest that the material was transported into the deposit from the surrounding proximal floodplain and that the assemblages reflect hydraulic sorting. A multifaceted palaeoecological investigation revealed significant habitat change between superposed assemblages of site QML796. The basal fossiliferous unit contained species that indicate the presence of a mosaic of habitats including riparian vegetation, vine thickets, scrubland, open and closed woodlands, and open grasslands during the late Pleistocene. Those woody and scrubby habitats contracted over the period of deposition so that by the time of deposition of the youngest horizon, the creek sampled a more open type environment. Sequential faunal horizons show a step-wise decrease in taxonomic diversity that cannot be explained by sampling or taphonomic bias. The decreasing diversity includes loss of some, but not all, megafauna and is consistent with a progressive local loss of megafauna in the catchment over an extended interval of time. Collectively, those data are consistent with a climatic cause of megafauna extinction, and no specific evidence was found to support human involvement in the local extinctions. Better dating of the deposits is critically important, as a secure chronology would have significant implications regarding the continent-wide extinction of the Australian megafauna.

Foraminifera are single cell protozoa that are ubiquitous in marine environments. The hard casings, or tests, of foraminifera are routinely studied in the earth sciences, particularly for palaeoenvironmental information. Foraminifera have been little studied by archaeologists, however, despite their potential to contribute to understandings of coastal site formation processes and localised palaeoenvironments. In this study techniques and methods of foraminiferal analysis are developed and applied to the problem of distinguishing between natural and cultural marine shell deposits, using the Mort Creek Site Complex, central Queensland, as a case study. Results allow unambiguous demarcation of the natural and cultural deposits studied based on patterns of foraminiferal density. Natural deposits were found to have more than 1000 foraminifera per 100g of sediment, while cultural deposits exhibited less than 50 foraminifera per 100g of sediment. The range of taxa represented in the foraminiferal assemblage is consistent with a shallow water sub-tropical marine ecosystem, indicating general environmental stability throughout the period of deposit formation. Findings are applied to re-evaluate previous models of site formation at the Mort Creek Site Complex.

Foraminifera are single cell protozoa that are ubiquitous in marine environments. The hard casings, or tests, of foraminifera are routinely studied in the earth sciences, particularly for palaeoenvironmental information. Foraminifera have been little studied by archaeologists, however, despite their potential to contribute to understandings of coastal site formation processes and localised palaeoenvironments. In this study techniques and methods of foraminiferal analysis are developed and applied to the problem of distinguishing between natural and cultural marine shell deposits, using the Mort Creek Site Complex, central Queensland, as a case study. Results allow unambiguous demarcation of the natural and cultural deposits studied based on patterns of foraminiferal density. Natural deposits were found to have more than 1000 foraminifera per 100g of sediment, while cultural deposits exhibited less than 50 foraminifera per 100g of sediment. The range of taxa represented in the foraminiferal assemblage is consistent with a shallow water sub-tropical marine ecosystem, indicating general environmental stability throughout the period of deposit formation. Findings are applied to re-evaluate previous models of site formation at the Mort Creek Site Complex.