Dental form and function in the early feeding diversification of dinosaurs

Abstract

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 dinosaurs 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. Sauropodomorphs 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 evolutionary 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.

Divergent strategies in cranial biomechanics and feeding ecology of the ankylosaurian dinosaurs

“…Ornithischian dinosaurs, from a likely omnivorous ancestral condition 48 – 50 , evolved an outstanding diversity of craniodental adaptations for different modes of herbivory 44 , 47 , 51 , 52 . In contrast to the highly specialised megaherbivores like hadrosaurs and ceratopsians, ankylosaurs have been interpreted as relatively less sophisticated herbivores feeding on softer plants 40 , 53 .…”

On a skeletally immature individual of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the upper Triassic of southern Brazil

“…The evolution of the body plan during the Triassic Period has received great attention (Ballell, Rayfield, & Benton, 2022; Bronzati et al, 2019; Cabreira et al, 2016; Damke et al, 2024; McPhee et al, 2018; Müller et al, 2018), especially regarding the acquisition of typical traits related to gigantism (Apaldetti et al, 2018; Lefebvre et al, 2022; Peyre de Fabrègues & Allain, 2020). Some studies examined biogeographical patterns (Griffin et al, 2021; Dunne et al, 2023), whereas others investigated the biology and ecology of the group (Aureliano et al, 2022; Ballell, Benton, & Rayfield, 2022; Bronzati et al, 2017; Cerda et al, 2022; Müller, 2022; Otero et al, 2019; Pol et al, 2021). Most of these studies are based on specimens from Triassic beds of Southern Brazil.…”