The Morphology and Occlusion of the Molariform Cheek Teeth in Some Macropodinae (Marsupialia: Macropodidae).

Abstract

The morphology and functional occlusion of the cheek teeth of Wallabia bicolor and Macropus giganteus are compared. W. bicolor seems to be essentially a browser and M. giganteus is predominantly a grazer. W. bicolor has a large sectorial premolar, weakly developed links, a plane tooth row with all the teeth in occlusion simultaneously in the adult, and no molar progression. M. giganteus has a reduced premolar, strongly developed links, a curved lower tooth row which meets the upper tooth row at a tangent allowing only a few teeth to be in occlusion at one time, and molar progression. The reconstruction of the occlusal cycles is interpreted mainly by examination of wear facet development and striae patterns. Occlusion in W. bicolor involves a strong anteroposterior action bringing the opposing surfaces together across a broad area. M. giganteus teeth occlude with an initial forward motion, followed by a lateral movement which avoids large surface-area contact. M. giganteus teeth seem to be more adapted to cutting fibrous, abrasive material. Species of Dorcopsis, Dorcopsulus, Dendrolagus, Thylogale and Setonix show the same general masticatory features as W. bicolor, but species of Macropus and Megaleia more approximate the M. giganteus condition.