Quantitative phylogenetically informed analysis of the radius of curvature of the three semicircular canals in 91 extant and recently extinct primate species and 119 other mammalian taxa provide support for the hypothesis that canal size varies in relation to the jerkiness of head motion during locomotion.
Overall, the three methods for quantification of anisotropy give broadly similar results, but there are systematic divergences that can be traced to their differences in data and processing, and which may impact on their relative utility in estimating mechanical properties.
The relatively thin trabeculae in large primates and other mammals suggest that increased skeletal loads in the postcranial joints of large mammals are probably mitigated not only through alterations intrabecular microarchitecture, but also through other mechanisms such as changes in cortical bone distribution, limb posture and gait speed.
The differences in femoral head trabecular structure among these taxa seem to be related to locomotor behavioral differences, reflecting variation in the use and loading of the hip joint during normal locomotion.
The application of this multivariate approach to analyses of trabecular bone morphology in recent and fossil primates may enhance the ability to reconstruct locomotor behavior in the fossil record.
A late Oligocene fossil assemblage from Ethiopia is reported, which constrains the migration to postdate 27 Myr ago, and yields new insight into the indigenous faunal dynamics that preceded this event.
The results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass.
Despite the overall similarities in the external postcranial anatomy of Omomys and Shoshonius, the results of this study indicate potentially important differences in the magnitude of the external loads at the hip joint, suggesting that these animals engaged in divergent locomotor behaviors.