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Abstract: The occipital bone of Neandertals contains an association of morphological features that is considered characteristic of this fossil human population. One of the possible autapomorphic traits of Neandertals is the presence of a suprainiac fossa, a horizontal oval-shaped depression located on the occipital plane. The question of whether suprainiac depressions observed on Neandertals and in other human samples are homologous has been widely discussed. The present study provides a detailed anatomical description of the fossa and of the underlying internal bone composition for Neandertals of various geographical and chronological origins, and of different developmental stages. The suprainiac fossa is systematically present on Neandertals from the earliest developmental stages as well as at the beginning of the differentiation of the Neandertal lineage. A similar pattern for the structural composition of the bone is found among all analyzed Neandertals (i.e., the suprainiac fossa corresponds to a thinning of the diploic layer with no substantial remodeling nor variation in the external table thickness in this area). On the contrary, the occipital depressions present on a sample of anatomically modern humans from Europe and Africa correspond to a resorptive area of the external cranial surface only. These depressions also differ in shape, disposition, and aspect on the external cranial surface from those fossae on Neandertals. We demonstrate that the depressions described in anatomically modern humans, as well as other hominin species, are not homologous to the suprainiac fossa of Neandertals. Consequently, we confirm the autapomorphic status of the Neandertal suprainiac fossa. [Copyright &y& Elsevier]

Abstract: Ontogenetic changes in the human femur associated with the acquisition of bipedal locomotion, especially the development of the bicondylar angle, have been well documented. The purpose of this study is to quantify changes in the three-dimensional structure of trabecular bone in the human proximal femur in relation to changing functional and external loading patterns with age. High-resolution X-ray computed tomography scan data were collected for 15 juvenile femoral specimens ranging in age from prenatal to approximately nine years of age. Serial slices were collected for the entire proximal femur of each individual with voxel resolutions ranging from 0.017 to 0.046mm depending on the size of the specimen. Spherical volumes of interest were defined within the proximal femur, and the bone volume fraction, trabecular thickness, trabecular number, and fabric anisotropy were calculated in three dimensions. Bone volume fraction, trabecular number, and degree of anisotropy decrease between the age of 6 months and 12 months, with the lowest values for these parameters occurring in individuals near 12 months of age. By age 2–3 years, the bone volume, thickness, and degree of anisotropy increase slightly, and regions in the femoral neck become more anisotropic corresponding to the thickening of the inferior cortical bone of the neck. These results suggest that trabecular structure in the proximal femur reflects the shift in external loading patterns associated with the initiation of unassisted walking in infants. [Copyright &y& Elsevier]