Three functional aspects (jaw movement, collapse of lophs by wear, and molar wear gradient) are described for Lophiodon and compared with typical lophodont dentitions in other mammals, e.g., Macropus, Pyrotherium and Deinotherium. The jaw movement is deduced from striations and guiding rails. In Lophiodon only phase I of the power stroke is documented by facets, whereas a minor phase II occurs in Macropus. During phase I the lophs perform two functions: cutting when the crests are passing each other, and compressing the bolus during further interlocking. When dentine is exposed the lophs collapse and lose their trenchant function and are grinding only. The sudden collapse of the lophs is partially due to the abrasion within the compression chamber, as seen in Dendrolagus. The molar wear gradient (the differential wear between the first and last molars) is low in Pyrotherium, intermediate in Lophiodon, and Deinotherium as compared with a low molar wear gradient in Tapirus or a high gradient in Macropus.