Environmental and biotic controls on conodont body size and teeth morphology as proxies for their feeding ecology

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Before the advent of jawed vertebrates, conodonts were the most abundant and diverse predators of early Palaeozoic oceans. Their phosphatic teeth abound in upper Cambrian through Triassic marine rocks. Thanks to their extraordinarily rapid morphological evolution, conodonts are established as a prime tool in biostratigraphy. Yet the feeding ecology that allowed this rapid diversification of food-processing structures remains unknown.The core question of this project is: How does conodont morphology reflect their trophic position, diet, and environmental conditions? This project will develop quantitative proxies to study conodont teeth and provide models of their variability in function of the abiotic environment (lithofacies) and biotic interactions (community structure). Teeth size will be quantified as a proxy for prey size, and thickness of the biomineralized tissue will be used as an indicator of durophagy. These parameters will be examined across well-documented environmental gradients in the middle Silurian carbonate succession of Gotland, Sweden. The project will allow distinguishing ecophenotypic variability from microevolutionary patterns. It will also identify the key controls on this variability by testing ecological models derived from other faunal groups, e.g. the relationship between body size structure in a community and the length of the trophic chain. These models will be independently tested by applying geochemical proxies for the trophic level of individual organisms. The project will provide a framework within which conodont morphological diversity across geological successions can be interpreted by partitioning it into ecophenotypic and evolutionary trends.