title: The shape of contention: adaptation, history, and contingency in ungulate mandibles.
abstract: Mandibles and teeth of ungulates have been extensively studied to discern the functional significance of their design. Grazing ungulates have deeper mandibles, longer coronoid processes, flatter incisor arcades, and more hypsodont molars in comparison to browsers. If the functional significance of both mandible and teeth shapes is well-established, it remains uncertain to what extent mandible shapes are really adapted to grazing, meaning that they evolved either to serve their current biological function or just as a structural requirement to accommodate higher crowned molars. Here, we address this question by studying the contribution of phylogeny, hypsodonty, and body size to mandibular shape variation. The mandible shape appeared to be significantly influenced by hypsodonty but not by body size. Interestingly, hypsodonty-related changes influenced the tooth row in artiodactyls and perissodactyls significantly but in the opposite directions, which is ultimately related to their different digestive strategies. Yet, we obtained a strong phylogenetic effect in perissodactyls, suggesting that their mandible shape should be strongly inherited. The strength of this effect was not significant within artiodactyls (where hypsodonty explained much more variance in mandible shape). Digestive strategy is deemed to interplay with hypsodonty to produce different paths of adaptation to particular diets in ungulates.
authors.affiliation: Dipartimento di Scienze della Terra, Università degli Studi di Napoli Federico II, L.go San, Marcellino 10, 80138, Napoli, Italy. pasquale.raia@libero.it
authors.forename: Pasquale
authors.initials: P
authors.lastname: Raia
authors.forename: Francesco
authors.initials: F
authors.lastname: Carotenuto
authors.forename: Carlo
authors.initials: C
authors.lastname: Meloro
authors.forename: Paolo
authors.initials: P
authors.lastname: Piras
authors.forename: Diana
authors.initials: D
authors.lastname: Pushkina
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D049628:Body Size; D005247:Feeding Behavior; D008322:Mammals / Q000033:anatomy & histology / Q000502:physiology*; D008334:Mandible / Q000033:anatomy & histology*; D010802:Phylogeny