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As the interface between the mandible and cranium, the mandibular ramus is functionally significant and its morphology has been suggested to be informative for taxonomic and phylogenetic analyses. In primates, and particularly in great apes and humans, ramus morphology is highly variable, especially in the shape of the coronoid process and the relationship of the ramus to the alveolar margin. Here we compare ramus shape variation through ontogeny in Homo neanderthalensis to that of modern and fossil Homo sapiens using geometric morphometric analyses of two-dimensional semilandmarks and univariate measurements of ramus angulation and relative coronoid and condyle height. Results suggest that ramus, especially coronoid, morphology varies within and among subadult and adult modern human populations, with the Alaskan Inuit being particularly distinct. We also identify significant differences in overall anterosuperior ramus and coronoid shapes between H. sapiens and H. neanderthalensis , both in adults and throughout ontogeny. These shape differences are subtle, however, and we therefore suggest caution when using ramus morphology to diagnose group membership for individual specimens of these taxa. Furthermore, we argue that these morphologies are unlikely to be representative of differences in masticatory biomechanics and/or paramasticatory behaviors between Neanderthals and modern humans, as has been suggested by previous authors. Assessments of ontogenetic patterns of shape change reveal that the typical Neanderthal ramus morphology is established early in ontogeny, and there is little evidence for divergent postnatal ontogenetic allometric trajectories between Neanderthals and modern humans as a whole. This analysis informs our understanding of intraspecific patterns of mandibular shape variation and ontogeny in H. sapiens and can shed further light on overall developmental and life history differences between H. sapiens and H. neanderthalensis . [ABSTRACT FROM AUTHOR]

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]