Metamorphosis is one of the most fascinating phenomena in the animal kingdom, implying an abrupt change in morphology and ecology during the lifetime of an individual transforming it from a larva into an adult. Metamorphosis can be thought of as a second birth for an animal, emerging as a completely different organism, despite being produced from the same genetic material. From butterflies to frogs, almost all the successful and speciose lineages of animals are metamorphic, suggesting that metamorphosis may be an important driver of biodiversity. At the time of the sixth mass extinction, where one-fifth of living species are threatened, understanding whether development can be a driver of morphological and functional diversity, and whether it may be advantageous in allowing populations to adapt rapidly to changing environments is of prime importance. The goal of META-MORPHOSIS is to test the impact of metamorphosis on morphological diversification by disentangling the factors (developmental, functional, and ecological) shaping morphological diversity. I aim to 1) identify the patterns of morphological and functional variation depending on developmental strategies across species throughout ontogeny; 2) shed light on the origin and evolution of metamorphosis using the fossil record; 3) understand how metamorphosis fosters diversity and to quantify its impact on the generation of biodiversity. To do so, I will study salamander species with different developmental strategies and ecologies throughout ontogeny using a combination of state-of-the-art approaches, including phenomics (geometric morphometrics), analyses of function (feeding kinematics and forces), phylogenetic comparative methods, development, paleontology and methods exploring diversification. META-MORPHOSIS will produce an unprecedented data set and analyses of diversification considering for the first time how morpho-functional, developmental, and ecological factors shape biodiversity through deep-time.