Comparison of tooth morphology and wear patterns in four species of wallabies

Abstract

Tooth morphology of two browsing macropods (brush-tailed rock-wallabies and swamp wallabies), one grazing species (tammar wallaby) and one mixed feeder (parma wallaby) are compared. The dental action of a single tammar wallaby was studied by cinefluoroscopy. Cinefluoroscopy showed independent rotation of each hemi-jaw on occlusion in the tammar, and the disposition of molar striae suggest a similar pattern of jaw movement in all four species. There was a close relationship between incisor and molar action in both grazing and browsing species. Initial occlusion of the anterior facets of the incisors brought about a grasping action in browsing species and a fine cutting action in grazing species. In both grazing and browsing species these incisor actions were coincident with a cutting action by the transverse lophs during molar occlusion. Subsequent independent rotation of each hemi-jaw results in fine cutting by the lateral facets of the incisors, in both grazers and browsers, at the same time as the molar arrays perform a crushing action in browsers and a secondary cutting action in grazing species. Thus the teeth of the four species showed a number of similarities (independent rotation of each hemi-jaw) along with some differences (incisor and molar actions) that appear to represent adaptations for efficient aquisition and oral processing of browse or graze.