title: Dental microwear in relation to changes in the direction of mastication during the evolution of Myodonta (Rodentia, Mammalia).
abstract: Observations of dental microwear are used to analyse the correlation between changes in molar tooth crown morphology and the direction of masticatory movement during the evolution of Myodonta (Rodentia, Mammalia). The studied sample includes 36 specimens representing both superfamilies of Myodonta (Muroidea and Dipodoidea) spanning 16 dipodoid and 9 muroid species. Microscopic scratches on occlusal surfaces resulting from contact between opposite teeth during mastication are analysed. Using these features, we determine the direction of masticatory movements. Microwear patterns display diverse orientations among Dipodoidea: oblique in Sicistinae, Euchoreutinae and Zapodinae, propalinal in Dipodinae and intermediary in Allactaginae. Similarly, Muroidea exhibit the following orientations: oblique in Cricetinae and propalinal in Arvicolinae, Cricetomyinae, Gerbillinae and Murinae. These various chewing types illustrate different evolutionary grades within the superfamilies. Acquisition of the antero-posterior masticatory movement in Dipodoidea is related to flattening of the molar occlusal surface. However, in some muroid subfamilies, this direction of mastication is associated with low-crowned and cuspidate molars (Cricetomyinae, Murinae).
authors.affiliation: Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine, CNRS UMR 6046, Faculté SFA, Université de Poitiers, 40, avenue du Recteur Pineau, 86022 Poitiers Cedex, France. Cyril.Charles@etu.univ-poitiers.fr
authors.forename: Cyril
authors.initials: C
authors.lastname: Charles
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Jaeger
authors.forename: Jacques
authors.initials: J
authors.lastname: Michaux
authors.forename: Laurent
authors.initials: L
authors.lastname: Viriot
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003817:Dentition; D008409:Mastication / Q000502:physiology*; D009144:Museums; D010802:Phylogeny; D012377:Rodentia / Q000033:anatomy & histology* / Q000145:classification