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The first mammals evolved as small-bodied insectivores in the shadow of the dinosaurs during the Mesozoic, but truly large body sizes and dominance of terrestrial ecosystems were only attained by mammals in the Cenozoic after the end-Cretaceous mass extinction. Yet, the extent and trajectory of mammalian palaeoecological diversity through the Late Cretaceous before the mass extinction and in its immediate aftermath in the early Paleocene remain incompletely understood despite centuries of fossil collecting and study. Recent developments in palaeodietary reconstruction using robust, quantitative proxies provide a timely opportunity to examine these issues. This thesis uses the well-resolved record from North America to test hypotheses related to mammalian dietary palaeoecology through the Late Cretaceous and early Paleocene. Firstly, a new quantitative review of dietary interpretations for Late Cretaceous mammals is presented, which reveals support for a rejection of the traditional Mesozoic 'suppression hypothesis'. However, the quality and consistency of interpretations are variable, highlighting the need for robust palaeodietary work in future. Secondly, a diverse set of extant herbivorous mammals is used to explore the benefits of applying and combining two dietary proxies: multi-proxy dental morphology analysis (MPDMA) and dental microwear texture analysis (DMTA). This study shows for the first time that multivariate metrics from both techniques are significantly but variably correlated and that dietary classification improves by combining both methods. Thirdly, MPDMA and DMTA are then applied to early Paleocene 'condylarths' (so-called 'archaic ungulates') from the San Juan Basin in New Mexico, providing strong support for the rapid recovery and radiation of placental mammals in the aftermath of the mass extinction. Finally, a novel multi-comparator approach to DMTA sheds new light on mammalian responses to an abrupt hyperthermal event in the early Paleocene, which has important implications for assessments of extinction risk amidst the current climate and biodiversity crises facing our planet.

The Raman Laser Spectrometer (RLS) aboard the Rosalind Franklin ExoMars rover is among the first instances of Raman spectroscopy, a technique well-established in the study of mineralogy and molecular structures, being used in the search for life on Mars. This thesis is focused on increasing the scientific return of the ExoMars RLS in the particular context of (presumed) challenging mixed mineralogy samples of exobiological interest including lacustrine sediments and evaporite minerals; more specifically, clay (phyllosilicate) minerals and nitrate salts. To accomplish this goal the thesis provides an end-to-end assessment of the capabilities of the RLS, with insights into how interdisciplinary approaches can increase its scientific return. The interdisciplinary approach adopted sought to maintain continuity between field observation, sample processing and spectral analysis using terrestrial analogues and flight equivalent hardware. This approach also forms an accessible framework for replicating ExoMars RLS processes and includes an in-depth review of calibrating an RLS equivalent repositioning state. The stage can be positioned to within 20μm and return to a previous position within 5μm. Constructed and tested using off-the-shelf hardware, it is well suited to research groups seeking to add positioning capabilities to analogue ExoMars systems. The Tecopa Basin, a former terminal basin in the Mojave Desert, California, was selected as sufficiently analogous to the proposed Oxia Planum rover landing site. The location provided samples with smectite clays which are abundant at Oxia Planum and subsurface evaporates, notably biologically accessible nitrogen which is a prerequisite for known forms of life but yet to be directly observed on Mars. Fourteen well documented and contextualised samples were taken from the basin with efforts made to first understand their stratigraphic contexts and relations to other samples in the data set. Sample contents analysed with RLS flight equivalent hardware, and ExoMars sample handling processes were identified in reference to spectral databases, in-situ field observations, laboratory standard minerals and cross-sample referencing. It was demonstrated that the RLS can differentiate geochemical changes across stratigraphic horizons within lacustrine sediments, including evaporite solubility gradients. However, detrital phyllosilicates and low concentrations of nitrogen compounds are extremely challenging to detect using RLS measurement protocols. This is due to weak Raman scattering of phyllosilicate minerals requiring sampling strategies distinct from those used for evaporites, a high variability in the contents of natural crushed mixtures and the nominal Raman sampling strategies being insufficient for the detection of nitrate at putative Martian concentrations. Whilst there is increasing scientific interest in phyllosilicates, this project would also advocate that additional resources both in the build up to and during the mission should be allocated to identification of nitrates on Mars given the unique capability of the ExoMars rover to sample the shallow subsurface and the importance of a robust subsurface nitrogen inventory for tracing Martian habitability and the evolution of the planet's atmosphere.

Agricultural intensification is one the principal drivers of environmental decline in agricultural landscapes. Declines in biodiversity, reduced capacity to store and sequester carbon, and degrading water quality are some of the most pressing concerns for managers of these environments. Agri-environment schemes (AES) seek to remediate this environmental damage and are increasingly guided by the natural capital approach and the concept of ecosystem services (ES). This research project aimed to develop a method to quantify ES trade-offs and synergies resulting from the potential land-cover change associated with AES policies, such as the Environmental Land Management Scheme (ELMS), the UK's latest AES policy, which is currently undergoing pilots. This was performed using fine-resolution land-use/land-cover (LULC) maps, and spatial models of crop production, carbon storage, pollinator abundance, water yield, and water quality. A new, fine-resolution (10 m) LULC map of the Upper Welland Catchment, (UK) offered improvements over existing coarser-resolution maps in terms of the quantification of semi-natural habitats (SNH) (woodland and grassland) across the landscape: estimating 123% higher woodland area, 41% higher grassland area, and 21% reduced arable area over digital maps with a resolution of 100 m. In collaboration with the Welland Rivers Trust, five land-cover change scenarios were modelled predicting the effects of potential future AES policy using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) toolkit and earth observation data from the European Space Agency's Sentinel-2 satellite. These simulated a "three-compartment model" based on land-sparing and land-sharing, where the landscape was split between high intensity farmland, low intensity farmland, and SNH. These scenarios ranged from those focused on crop production, to those seeking to restore extensive areas of SNH to the landscape. Estimated ES provision for wild-bee abundance, carbon storage, and water quality all benefitted from the restoration of SNH across the landscape increasing by 17%, 59%, and 58% respectively between the baseline and most extensive SNH restoration scenario. These ES typically exhibited synergistic interactions and increased in supply with one another across the landscape. In contrast, estimated crop production was reduced by 43% between the baseline and most comprehensive SNH restoration scenarios, and was associated with trade-offs with the increased supply of the other ES. Estimated water yield was minimally affected by the land-cover scenarios and exhibited a mixed dynamic in which trade-offs and synergies increased in approximately equal proportions between the scenarios. When simulating conservation objectives where all ES were weighted equally, the most extensive land-cover change scenario (193% increased woodland area, 21% increased grassland area, and 43% reduced arable land-cover) provided the optimal increase in supply of the ES bundle. When greater priority was given to crop production, the optimal scenario varied, with an intermediate scenario (52% increased woodland area, 19% increased grassland area, 19% reduced arable land-cover) providing the best outcomes for the ES bundle. Overall, the research results demonstrate the significant contributions that spatial models of ES can make to the design and implementation of future AES policies. Restoring SNH to agricultural landscapes is likely to create substantial benefits to ES supply, particularly when spatially targeted in areas of greatest potential effect. This new method to quantify ES trade-offs and synergies can be easily applied to varied landscapes and is able to account for differing local conservation priorities.

Melanin is a ubiquitous pigment found throughout a variety of vertebrate tissues where it fulfils several important roles including colour patterning, ultraviolet protection, and transmission of nerve impulses. It is synthesised in a membrane-bound organelle termed a melanosome, the geometry of which can aid in determining the function of various pigmented tissues. Melanin and melanosomes are extremely recalcitrant and are known to fossilise and palaeontologists have used the presence of melanin and the geometry of melanosomes to address numerous evolutionary questions, from reconstructing the plumage colours of feathered dinosaurs, to the development of a sophisticated camera-style eye in lamprey. Whilst melanin and melanosomes have been shown to remain relatively unaltered during diagenesis, what is not yet fully understood is whether post-mortem processes such as decay alter the geometry of melanosomes or affect the distribution of melanin within the pigmented anatomy of phylogenetically significant organisms. To address these uncertainties, this thesis presents the results of four comprehensive taphonomic experiments investigating the pigmented anatomy of aquatic vertebrates, three of which investigate melanosome geometry and melanin distribution during decay in extant and fossil lamprey alongside distinctly patterned teleost fish, and one investigates the pigmented anatomy of a lamprey-like Devonian fossil Euphanerops longaevus. It was shown that melanosomes from different lamprey tissues retained their geometry throughout decay, with eye melanosomes providing the only exception, changing their geometry from sub-spherical to more elongate forms. Crucially, these changes were not sufficient to alter any interpretations of function based on their shape. Melanosome geometry was also investigated using Procrustes superimposed semi-landmark coordinates in the hope of providing more subtle shape information. However, our results demonstrate that using aspect ratios is sufficient to capture the extent of melanosome geometries. Melanin distribution was found to change during decay, either aggregating into globules or dispersing into surrounding tissues. This alteration can lead to the appearance of new skin pigment patterns. Anatomical features in Euphanerops preserve melanosomes and melanin, extending the fossil record of this pigment by 70 Ma.

Explosive eruptions from flooded caldera volcanoes are some of the most violent on Earth. Taal Caldera Volcano, Philippines, is one of the most dangerous because it is poorly understood and in the middle of a densely populated area. A new stratigraphic framework for Taal's prehistoric eruptions increases the number of major (>5 km3 DRE) explosive eruptions from 4 to 7, records 3 new minor eruption-units, and newly identifies the Sampaga Formation as the oldest pyroclastic eruption-unit. This study significantly increases the estimated eruption volume for the youngest major eruption-unit, the Buco Formation, from 3 km3 to 28 km3 DRE, and for the largest eruptionunit, the Pasong Formation, from 31 km3 to 90 km3 DRE. Ash aggregates, fluidal juvenile bomb-rich and poorly-lithified ignimbrites, the presence of fine ash-rich cross-bedded facies, and active and passive ash grain textures are more common in younger eruption-units, especially the Buco Formation, compared to older eruption-units like the Alitagtag Formation. This study therefore hypothesises that water had more access to erupting magma during recent major eruptions, although no major eruption is thought to have been triggered by the explosive interaction of water with magma. All major eruptionunits show evidence of plagioclase, pyroxene and magnetite fractionation, although magma evolution for the youngest three eruption-units was dominated by mixing processes. Over time, major eruption-units have been becoming more mafic (from 63 wt.% SiO2 for the Alitagtag Formation to 58 wt.% SiO2 for the Buco Formation); almost all major eruption-units can be chemically distinguished from each other using a combination of Y, Fe2O3 and Cu. Major eruptions are punctuated by smaller, but more frequent explosive eruptions, similar to Taal's historical eruptions, which continue today and upon which hazard maps are based. However, this study has shown that Taal's prehistoric eruptions were significantly larger and more frequent than previously thought and that major eruptions have occurred in the past, and therefore could in the future, following a phase of smaller-scale eruptions, similar to Taal's current eruptive phase.