, 2010), but that it is among the poorest performers. Under almost all loadings, mean and maximal VM strain values between the two polar bear specimens are closer to each other than to any other species. This is supported by the results of pairwise two-factor ANOVA. Table 2 shows that at α = 0.1, P < α for all possible pairs of polar bears and other species, except between polar bear (SAM-ZM 35814) and polar bear (AM M42656), suggesting that the mean VM brick strain distributions in the two polar bears are statistically similar. Our finding that the polar bear is arguably the poorest

performer is surprising given its status as the only living hypercarnivorous ursid. check details Our results agree with a recent analysis. (Slater et al., 2010), which compared the mechanics of a polar bear cranium with those of a brown bear, from which polar bears have recently diverged (Lindqvist et al., 2010). We suggest that the skull biomechanics of the polar bear, which primarily ingests easily processed

blubber (Perry, 1966), are consistent with predation upon relatively small prey. Moreover, its primary prey is semiaquatic and poorly equipped to resist capture on land. Regarding diet in A. africanum, it was clearly capable of generating very high bite forces for its size, and its skull was well-adapted to resist both these and relatively Ivacaftor supplier high extrinsic loads, and these are features that would be expected in a species that regularly kills and/or scavenges on relatively large prey. However, our results also show that the exclusively herbivorous giant panda is similarly well-adapted to sustain relatively Molecular motor high loadings, indicating that ursid feeding behaviour cannot be predicted on the basis of our FEA alone. Many craniodental variables have

been considered by previous authors. Relative grinding area (RGA) is perhaps the most reliable indicator of the relative importance of plant material in the diet, with low values correlating with decreased reliance on plants (Sacco & Van Valkenburgh, 2004). On this basis, it is unlikely that similarities in mechanical performance between the A. africanum and the giant panda are a consequence of similarities in diet. We calculate a value of 1.47 for RGA in our specimen of A. africanum, well below values for RGA evidenced in any living bears, the next lowest being 1.83 in the polar bear (Van Valkenburgh, 1989). Relative carnassial blade length (RBL) has also been regarded as a strong indicator of the importance of vertebrate prey in carnivoran diets, and RBL in A. africanum is also considerably higher than in extant bears. However, among extant bears, the only hypercarnivore that has relatively short carnassial blades is the polar bear (Sacco & Van Valkenburgh, 2004), perhaps because it feeds mostly on blubber as opposed to meat or bone (Perry, 1966), as previously mentioned.