As a prerequisite to direct comparison of the metatherian and eutherian mammals that cohabited during the time period encompassing the K/T boundary, the degree to which compatibility of tooth wear in extant Australian marsupial and worldwide placental herbivores has been assessed. The aim of this pilot study was to determine whether the microwear patterns recorded on their molars are indeed the same among animals of the same dietary niche, or whether the large difference in jaw architecture and chewing strokes between modern metatherians and eutherians has an effect on the signal—whether function or phylogeny determines microwear patterns.  

Results/Conclusions

Low-magnification microwear analysis has so far been shown to be effective in differentiating between grazers, browsers, and hard-object herbivores in extant ungulates, lemurs, notoungulates, xenarthrans, sciurids, and Macropod marsupials. The present study includes members of the above with the addition of selected rodents and members of the Australidelphia superorder (in addition to the Macropodidae). Because the aim of the study was to examine the degree to which members of the same feeding guild have similar microwear patterns, species were chosen based on their being relatively specialized feeders belonging to grazing, browsing, and hard-object feeding niches; mixed feeders were excluded. No statistical difference between marsupial and placental mammals occupying the same feeding niche was found, providing strong evidence for functional convergence in these two groups. These results support the use of microwear as a dietary proxy across the metatherian and eutherian mammals in the fossil record.