Dental form and function in the early feeding diversification of dinosaurs

Dinosaurs evolved a remarkable diversity of dietary adaptations throughout the Mesozoic, but the origins of different feeding modes are uncertain, especially the multiple origins of herbivory. Feeding habits of early di-nosaurs have mostly been inferred from qualitative comparisons of dental morphology with extant analogs. Here, we use biomechanical and morphometric methods to investigate the dental morphofunctional diversity of early dinosaurs in comparison with extant squamates and crocodylians and predict their diets using machine learning classification models. Early saurischians/theropods are consistently classified as carnivores. Sauropo-domorphs underwent a dietary shift from faunivory to herbivory, experimenting with diverse diets during the Triassic and Early Jurassic, and early ornithischians were likely omnivores. Obligate herbivory was a late evolu-tionary innovation in both clades. Carnivory is the most plausible ancestral diet of dinosaurs, but omnivory is equally likely under certain phylogenetic scenarios. This early dietary diversity was fundamental in the rise of dinosaurs to ecological dominance.

Automated summary

This study investigates the dental morphofunctional diversity of early dinosaurs and predicts their diets using biomechanical and morphometric methods. The results suggest that early saurischians/theropods were carnivores, while sauropodomorphs underwent a dietary shift from carnivory to herbivory. Early ornithischians were likely omnivores. This early dietary diversity played a fundamental role in the rise of dinosaurs to ecological dominance.