This study will test the hypothesis that wear patterns on fossil conodont teeth differ according to whether species lived on the sea floor or above it. If wear does differ, as it does in fish teeth, this will provide a new way of increasing the reliability of conodonts in geological and deep-time environmental analysis. Conodonts were small, eel-like primitive fishes. They have been extinct since the end of the Triassic, but the 300 million year record of their microscopic fossil teeth is exceptionally complete, and they are easy to obtain in large numbers by dissolving limestone in weak acid. Consequently, conodonts are among the most important tools for geological dating - determining when rocks were laid down and when geological events occurred. They are also increasingly important tools for investigating the palaeoclimate, palaeotemperature and palaeooceanography of geological periods in deep time, studies which are important for understanding the context of current climate change. For example, investigations of the oxygen isotopes in conodont teeth are providing new insights into glaciations, sea level and sea temperature hundreds of millions of years ago. Conodonts are particularly suited to such studies because the structure and calcium phosphate composition of their tooth crown maximises the chances that the chemical signatures recorded in the teeth reflect ocean conditions at the time the animal was alive, and minimises changes caused by the process of fossilization. Recent work indicates that isotopic analyses based on conodont crown tissue give more reliable results than analyses of any other fossil teeth or shells of comparable age. Realising the full potential of conodonts, however, requires that we can constrain their ecology and mode of life. Differentiating between benthic taxa, which lived on the sea floor, and pelagic taxa, which lived away from the sea floor and in surface waters, is particularly important. The best taxa for geological dating are pelagic, because pelagic taxa have broader (potentially global) distributions. They also disperse more rapidly, so the time at which a newly evolved pelagic species first appears in the fossil record in different locations is more likely to be synchronous (important for establishing the age equivalence of rock sequences). Analyses that interpret shifts in the chemical composition of conodont tooth crowns in terms of temperature or sea level must exclude the possibility that differences between samples reflect differences in the depth habitat at which the sampled conodont species lived (deeper water is cooler). Unfortunately, the mode of life of conodonts is poorly constrained, and this causes problems. We know that they were active swimming animals that ranged from shallow nearshore through to deep ocean environments, but determining whether a particular species occupied a benthic or a pelagic niche is difficult. Current methods, based on hypothetical distributions of conodonts along depth gradients, are rather crude and generally unreliable. This proposal aims to develop a new approach to constraining the depth habitats of conodont taxa. Recent work led by the investigator discovered that patterns of tooth wear in benthic feeding fish differ from those of pelagic feeding fish and can be used to study changes in feeding in fossil fish. Does the same apply to conodonts? In order to find out we will conduct the first systematic analysis of conodont tooth wear and test the hypothesis that pelagic feeding and benthic feeding species exhibit different wear patterns. This will be based on microscopic investigation of hundreds of conodont teeth and detailed statistical analysis of the patterns of wear preserved on their surfaces. These teeth will be taken from samples where, unlike most conodonts, the palaeoecology of the species is well constrained. If differences are detected, isotopic analysis will provide independent data concerning temperature/depth habitat.

The Permo-Triassic mass extinction (PTME; c. 252 Ma) was the most catastrophic biotic event of the Phanerozoic with up to 96% of marine animals going extinct. This event was triggered by massive volcanic eruptions which led to a series of environmental cascades in the oceans, such as rapid and extreme greenhouse warming, ocean anoxia and ocean acidification. The PTME had long lasting effects on the evolution of life with current opinions stating that marine ecosystem recovery took anywhere between 5 to 50 million years. It has also been hypothesised that the PTME caused a permanent ecological regime shift in the world's oceans, marking the end of Palaeozoic benthic ecosystems largely made up of sessile suspension feeders and catalysing the "Mesozoic Marine Revolution", a predator-prey arms race which led to increasing levels of ecological complexity. However, previous attempts to quantify the speed and nature of the recovery interval from the PTME have relied upon indirect measures of ecosystem structure and complexity such as compilations of taxonomic vs functional diversity, qualitative interpretations of ecosystem recovery, and attempts at quantifying changes in life habit and evidence of predation intensity through time. However, to thoroughly test such hypotheses, analyses need to be conducted within a whole ecosystem framework which make use of community ecology methods in order to model ecosystem structural changes via trophic networks (i.e. food webs) through the recovery interval and beyond. This project will explore a novel approach to pushing the frontiers of palaeobiological research via interdisciplinary methods combining recent advances in ecological modelling with palaeontology. Specifically, we will test how marine ecosystems recovered from the PTME and whether this biotic crisis truly represented the beginning of the origins of modern marine ecosystem structure. We will use the rich marine fossil record from South China to model community structure across the PTME and long recovery interval through the Triassic whilst accounting for preservation bias in the fossil record. We will then use the Paleo Foodweb Inference Model to build food webs from ecological traits easily identifiable from the fossil record and then track community structure and function across the PTME and into the recovery interval in the Triassic. This analysis will provide the most precise analysis of how the largest mass extinction in Earth history altered marine ecosystem structure and whether this event heralded the onset of the Mesozoic Marine Revolution and the origins of modern marine ecosystem structure.

Stalagmites and other carbonates deposited in caves provide a potentially powerful record of past climate. Stalagmites have a wider geographical dispersion than lakes or ice cores and provide an ideal terrestrial complement to marine sediment cores. Stalagmites have additional advantages in that they can be very accurately and precisely dated, and that they suffer no sedimentary mixing so can provide very high resolution geochemical records. These advantages have led to a burgeoning interest in reconstruction of climate from stalagmites in the last decade - a trend that looks set to continue. There is, however, a big problem with such stalagmite paleoclimate research. This is that we cannot yet reliably turn geochemical measurements in stalagmites into quantitative information about the past climate. In some locations, stable-isotope data provides qualitative information about change, but we desperately need to develop better understanding of these and other geochemical proxies so we can reliably use them to reconstruct the past. The work proposed here will provide understanding of stalagmite paleoclimate proxies through a series of laboratory experiments mimicking the cave environment in which stalagmites grow. We have built a laboratory apparatus that allows super-saturated waters with high CO2 contents to drop onto glass-plates in closely controlled conditions and to degas to form calcite in a manner identical to that seen in the cave environment. We have demonstrated the success of this apparatus and used it to assess the role of temperature and drip-rate in controlling stalagmite geochemistry. Here we propose to replicate these experiments, and to go beyond them to also understand the role of variables such as pCO2, solution saturation, and humidity in controlling stalagmite geochemistry. We will characterize the samples grown in this way both for their chemistry and for their crystallographic features, and apply some simple models to develop a significantly better understanding of trace-metal and stable isotopes incorporation into stalagmites, under conditions of both thermodynamic equilibrium and kinetic fractionation. This work will have direct implications for the interpretation of existing and new stalagmite records, with perhaps the clearest reward coming in the interpretation of high-resolution climate records. We will also apply some new geochemical tools which have seen little previous application to the cave environment. The clumping of minor isotopes within molecules (such as the carbonate ion) has been shown to be temperature dependant, providing a potentially powerful paleothermometer in caves, but one that is unfortunately complicated by kinetic effects. Our laboratory samples will help, via a collaboration with Yale University, to understand the uses and pitfalls of this clumped-isotope paleothermometer. We will also measure some relatively unexplored isotope systems such as Ca, Li, Sr, and Mg isotopes to assess their use as paleoproxies. Finally, we will assess, by adding microbes to our experiments, the possibility that life plays a role in the precipitation and chemistry of stalagmites. Such cave carbonates are normally thought to grow inorganically, but very recent culturing and sequencing work has uncovered a diverse microbial assemblage on stalagmite surfaces, with some species known to have a role in carbonate precipitation in other environments. We will include microbial strains found in the natural cave environment in our experiments to assess the importance of life for growth of cave carbonates. In total, the outcome of these laboratory experiments will be a much improved understanding of the geochemistry of stalagmites, significantly advancing their usefulness as archives of past climate, and therefore providing new insights into the magnitude, timing, and processes of climate change on the continents.

Charles Darwin's great dilemma was why complex life in the form of fossil animals appear so abruptly in rocks around 520 million years ago (Ma), in what is widely known as the Cambrian explosion. During recent decades, exceptionally preserved animal fossils have been found throughout the Cambrian Period, which began 20 million years earlier, and arguably even through the entire, preceding Ediacaran Period, which directly followed the worldwide 'Snowball Earth' glaciations (~715 - 635 Ma). Most of these exceptional deposits were discovered in South China, which possesses the best preserved and dated geological record of the marine environment for this time. In this genuinely collaborative UK-China project, we propose to use the South China rock archives to construct a much higher resolution, four-dimensional (temporal-spatial) picture of the evolutionary history of the earliest animals and their environment. Towards this endeavour, our group combines complementary expertise on both the UK and Chinese research teams in: 1) geochronology - the dating of rocks; 2) geochemistry - for reconstructing nutrient and the coupled biogeochemical cycle (O and C); 3) phylogenomics - for making a genetically-based tree of life to compare with, and fill gaps in the fossil records; and finally 4) mathematical modelling, which will enable us to capture geological information, in such a way as to test key hypotheses about the effects of animal evolution on environmental stability. Our project aims to address three central scientific questions: 1) How did the coupled biogeochemical cycles of C, O, N, P and S change during these evolutionary radiations?; 2) Did environmental factors, such as oxygen levels, rather than biological drivers, such as the emergence of specific animal traits, determine the trajectory of evolutionary change?; and 3) Did the rise of animals increase the biosphere's resilience against perturbations? This last question has relevance to today's biosphere, as the modern Earth system and its stabilising feedbacks arose during this key interval. By studying it in more detail, and establishing temporal relationships and causality between key events, we can find out how the modern Earth system is structured, including which biological traits are key to its continued climatic and ecosystem stability. One further goal of this project is to strengthen existing and establish new, and genuinely meaningful collaborations between the UK and Chinese investigators. We will achieve this by working jointly in four research teams, by integrating all existing and new data into an international database, called the Geobiodiversity Database, sharing a joint modelling framework, and by providing collaborative training for the early career researchers involved in this project each year of the project.

The rare earth elements (REE) are classified as critical metals because they are essential for renewable energy technology such as wind turbines, and for the development of electric motors for low carbon transport. Current government policies in the UK and globally are driving an expansion in use of these technologies, but the supply of the metals needed is currently limited and the increase in use cannot be met from exisiting raw material sources or recycling. There is therefore a need to investigate the formation of mineral resources for these metals, to determine the potential for new resources, and to improve efficiency and minimise environment impact in their extraction. Currently the REE are mainly extracted and processed in China, and the Universities of Brighton and Exeter currently have research links with Peking Univeristy in this area. This project aims to build and expand this research network, primarily by developing a new collaboration with the State Key Laboratory for Geological Processes and Mineral resources in Wuhan, and then by running workshops involving researchers from China and the rest of world, to define key research problems in the area, and build an international team to address them. A primary focus of the parternship will be to study processes of enrichment and separation of the REE during weathering of carbonatites (igneous carbonatite rocks). Current global REE supply is met from unweathered bedrock deposits in carbonatites, or from weather grantic rocks (sometimes called ion adsorption deposits). However, weathered carbonatites have some of the highest concentrations of the REE, and preliminary data from the Lizhuan carbonatite in China suggest that they may combine characteristics of carbonatite and ion adsorption deposits. This means there may be potential for developing lower environmental imapct (energy cost) ways of extracting the REE from these deposits. The project will study the mineralogy and geochemistry of these deposits, and use the data collected as the basis for setting up new international projects to further develop research on REE resources.