Was the Early Pliocene hominin 'Australopithecus' anamensis a hard object feeder?

Features that are characteristic of early hominin jaws and teeth have been widely perceived as having evolved to process food items that likely accompanied the expansion of drier, more open habitats in the Late Miocene and Early Pliocene. 'Australopithecus' anamensis has been envisaged as having undergone a dietary shift to harder and more brittle foods than were eaten by its presumptive ancestor, and has been argued to represent possibly the first hominin to have been adapted to such dietary objects. We were able to obtain data pertaining to molar microwear (and, thus, diet) for only three molars (individuals) of 72 available specimens of 'A.' anamensis, but the pattern common to all suggests that chimpanzees and gorillas constitute the best modern analogues for dietary preference in this Early Pliocene hominin. Microwear in 'A.' anamensis differs notably from that typically exhibited by extant primates that consume hard objects. Although 'A.' anamensis appears to have had the trophic capability to process a fairly wide range of foods, including the hard, brittle items that might be expected in the sorts of environments in which it is found, those few individuals we have been able to sample do not appear to have ingested these sorts of items while their microwear was being formed. The wear fabric exhibited by 'A.' anamensis is entirely encompassed by the pattern that defines Praeanthropus afarensis, and it is perhaps significant that this pattern appears to have remained little changed in this presumptive descendant of 'A.' anamensis. Explanatory scenarios that describe 'A.' anamensis as part of an evolutionary trajectory involving a more heavily masticated diet of hard, brittle items may need to be reconsidered.