Orangutan (Pongo spp.) fossils have been found throughout much of Pleistocene Southeast Asia. Today, Pongo is restricted to three living species on the islands of Borneo and Sumatra. They are predominately frugivores, and during fruit masting events their diets can consist entirely of fruit. However, food procurement strategies between masting events differ between islands and thus species. Sumatran orangutans (Pongo abelii) are largely able to fall back on non-masting fruit species, such as figs, such that they can maintain higher quality diets compared to their Bornean counterparts (Pongo pygmaeus), who ingest more lower quality and tougher foods between mast events. However, diets of fossil orangutans remain largely unknown. We investigated the diets of Sumatran orangutans from the Pleistocene deposits of the Padang Highlands, western Sumatra, using dental microwear texture analysis. We tested whether the diets of the fossil species were similar to those of Bornean orangutans, all great apes generally, and macaques that occupy similar habitats to modern orangutans, in order to gain insights into palaeoenvironments present in western Sumatra. We found that fossil orangutans consumed foods less tough than modern Bornean Pongo pygmaeus, and thus presumably more fleshy fruits (absent of significant seed mastication). We found no differences in the amount of hard object feeding between modern and fossil orangutans. Taken together, we suggest that Pleistocene orangutans from western Sumatra had similar diets to Pongo abelii, indicating that masting events were not a significant contributing factor in their intake of fruit. Finally, we suggest anisotropy values in orangutan dental microwear may be an important marker for fruit masting events in the Pleistocene.

European arrival into Australia had large-scale impacts on the local flora and fauna. Most notably, Europeans brought with them numerous non-native species, including the European red fox (Vulpes vulpes), European rabbit (Oryctolagus cuniculus), and the goat (Capra hircus) among many others. The introduction of these species had significant consequences on native Australian mammals, causing some small-to medium-sized herbivores to become geographically restricted to primarily islands. Here, we examined the dietary ecology of the quokka (Setonix brachyurus), a native marsupial herbivore with a restricted geographic range in Western Australia before and after European arrival. Fossils from south-western Australia and modern specimens were examined via dental microwear texture analysis and stable isotope analysis to assess whether the diet of the quokka had changed dramatically over time. Collectively, we help clarify whether there were any ecological reasons as to why this marsupial became geographically restricted, aside from the presence of invasive predators on mainland Australia. The quokka maintains a browsing diet from the Pleistocene to the present on the mainland, but modern island populations eat drier and tougher foods when living on islands lacking invasive mammals. There is also an apparent shift in the feeding environment of the quokkas on mainland Australia, from more open forests/shrublands in the Pleistocene to denser and wetter forests. Multi-proxy data collectively indicate that the restricted range of the quokka today is most likely a result of predation from non-native taxa and/or other human influences -not because of a lack of suitable habitat.

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