Novel anatomical adaptations and mechanisms for feeding are often postulated as 'key innovations' that spark the diversification of major clades. However, the mechanics of these adaptations are rarely quantitatively or rigorously tested, seriously undermining the validity of these hypotheses. Moreover, the majority of biomechanical analyses are carried out on single exemplar organisms, whereas a comparative phylogenetic context is critical to understanding the impact of feeding on evolutionary history and testing macroevolutionary hypotheses. Dinosaurs dominated terrestrial ecosystems for >130 million years, exhibiting a tremendous range of body sizes, shapes and ecologies. The earliest dinosaurs and their ancestors were generalists and minor faunal components. Dramatic increases in body size, diversity and abundance occurred during the Late Triassic-Early Jurassic (230-180 million years ago), and various factors have been implicated in dinosaur success. It is thought that the appearance of novel feeding adaptations permitted ecological diversification. However, this engaging 'functional story' has not been tested in a quantitative, hypothesis-driven comparative framework and previous work has focused on derived dinosaur taxa with extreme morphologies (e.g., Tyrannosaurus, Diplodocus), ignoring forms close to the base of Dinosauria. For these reasons, dinosaurs are an ideal model system for integrating data on feeding biomechanics with phylogeny, allowing more rigorous investigation of the relationship between functional diversity and clade dynamics. In this project we aim to comprehensively understand the consequences of functional changes in dinosaur skull biomechanics during the origin and early evolution of dinosaurs, a key moment in life's history. The proposed project is particularly timely given the availability and integration of cutting-edge computational methods for biomechanical analyses and new discoveries of early dinosaurs and their ancestors. We will integrate principles and methods from palaeontology, biology and engineering to reconstruct skull anatomy and function in 15 early dinosaur and dinosauriform taxa. CT scans and visualization software will be used to create 3D computer models. Information from the original fossils and living crocodilians, birds and lizards will be used to reconstruct head musculature. Using these reconstructions and multi-body dynamics analysis, we will model jaw motions during feeding, estimate bite forces along the tooth row and calculate maximum jaw closing speed. We will integrate results from dynamic models with finite element analysis and geometric morphometrics to test how the skulls respond to feeding-induced loads. In addition, we will run simulations on three living species to ensure model predictions are accurate. Results from these analyses will provide evidence for the jaw function and potential diet of early dinosaurs, and whether they became more specialized in terms of feeding performance during their evolution. Finally, we will compare the appearance of feeding characters to dinosaur diversity patterns to determine what role feeding had in their early evolution and success. Palaeontologists, anatomists, biomechanists, evolutionary biologists and engineers will benefit from this work, which will set new benchmarks for performing evolutionary biomechanics in living and fossil animals and will establish new UK, European and overseas collaborations. This project will also generate new methodological advances that can be applied to other clades and other functional questions. Finally, the technological and visual aspects of this work and its focus on early dinosaurs will appeal to the general public, offering numerous engagement opportunities and media interest that will contribute to increased public understanding of scientific principles and methods, and will ensure wide dissemination of this work.