Book excerpt: Reconstructions of diet provide valuable insights into the ecology and evolutionary history of animals and humans in the fossil record, and the history of relationships between animals and humans. Reconstruction of past diets allows tracking numerous ecological and behavioural aspects through time and across diverse geographic areas, such as, but not limited to: trophic position, niche sharing and niche partitioning, past vegetation, migration patterns, ontogenetic and individual diet choices, and adaptations to changing environment. It also is a useful tool to track climatic change. More broadly, these insights are key to reconstructing and understanding the structure, composition, and function of past ecosystems. Multiple approaches have been proposed to infer paleodiets, including the integration of multiple proxy approaches.