Palatal morphology predicts the paleobiology of early salamanders

Ecological preferences and life history strategies have enormous impacts on the evolution and phenotypic diversity of salamanders, but the yet established reliable ecological indicators hinder investigations on the paleobiology of early salamanders. Here we statistically demonstrate using geometric morphometric analysis that both the shape of the palate and many non-shape variables particularly associated with vomerine teeth are ecologically informative in early stem- and basal crown-group salamanders. The morphology of the palate is heavily impacted by convergence constrained by feeding mechanisms and also exhibits clear stepwise evolutionary patterns with alternative phenotypic designs to cope with similar functional demand. Paleoecological disparities in early salamanders had took place before the Middle Jurassic and have achieved all ecological preferences in the Early Cretaceous. Metamorphosis is significant in the expansion of ecomorphospace of the palate in early salamanders. The common ancestor of salamanders is metamorphosed and terrestrial, and share unified lifestyles with other modern amphibians.