The structural characteristics of the supraorbital ridge in three extent primate species and fossil Neanderthals are described in this study. Surface morphology and patterns of trabecular organization as observed in cross-sectional collections of Pupio, Mucucu and Pun are compared with similar traits encountered in the Pech de 1'Aze infant, Gibraltar child, and La Quina 5, La Chapelle-aux-Saints, Broken Hill, Skhul V, Skhul IX, Tabun I and Gibraltar adult Neanderthals. Periods of rapid appositional growth of the browridges by means of fine cancellous bone formation and its subsequent remodeling and consolidation are temporally correlated with dental development and eruption sequences. The purpose of this report is (1) t o identify surface indicators of trabecular organization and browridge formation in Neanderthals, (2) to compare these data with similar information about macaques, chimpanzees, and olive baboons, and (3) to demonstrate how these comparisons can be used in addressing developmental, functional, and evolutionary questions about browridge formation and craniofacial morphogenesis in primates. was determined on the basis of dental eruption sequence and attrition status (Krogman, '30; Schultz, '35; Bramblett, '69).The nature of the bone surface in the brow region of each of the skulls was noted; samples of bone were then removed from the supraorbital region of the non-hominid skulls and prepared and analyzed using standard light microscopy and scanning electron microscopy techniques. RESULTS MacroscopicFigures la,b-3a,b show variations of a surface pattern that we observed in the supraorbital region of several monkey, ape and fossil hominid skulls. This trait, described as "vermiculate bone" by Tappen ('731, was found along portions of the supraorbital margin in the Gibraltar child, Skhul V, Skhul IX, Tabun I, and Broken Hill skulls; Tappen ('73, '78) has described the trait in the brow region of numerous Neanderthal specimens. We encountered variations of the pattern in the supraorbital region of many of the macaque and chimpanzee skulls considered during this analysis. The vermiculate pattern is absent or virtually '

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Data from neural crest cultures indicate that cell surface coat material (CSM) is directly involved in cellular migration and events surrounding differentiation. To investigate whether the CSM also has a morphogenetic role, embryos of the amphibian Arnbystorna maculatum were examined ultrastructurally throughout the stages of neurulation. Segments of the neural axis were fixed in glutaraldehydecontaining Alcian blue 8GX, which reportedly enhances preservation of CSM, and were postfixed in OsO4 containing 1% lanthanum nitrate, which stains the CSM. The medial groove formed by the appearance of the neural ridges contains a large amount of CSM and numerous vesicles coated with lanthanum-positive material. In contrast, the lateral ridge surfaces are covered by a small amount of uniformly distributed CSM and a paucity of vesicles. As the ridges begin to fold there is a progressive increase in the amount of CSM within the presumptive neural tube region. Further convergence of the neural folds is accompanied by an increase of CSM at their leading edges. As the folds approximate each other, lanthanum-positive material physically bridges the gap. However, as the apposing tissue actually abuts to form the neural tube, no CSM is observed in the remaining interspace. The specific distribution and sequential accumulation of cell CSM during the events of neurulation strongly suggest its direct participation in the morphogenetic process.The migratory and differentiative activities of cell populations during embryogenesis normally occur in a temporal and spatial pattern of awesome precision and complexity. Vogt's elegant fate-mapping experiments with amphibian embryos (30, 31) first demonstrated consistent directions of morphogenetic movement by various cell groups. Wilson's cellular reaggregation studies with sponges (37) introduced the concept of histogenetic specificity, i.e. a mixed-species population of cells will selectively reaggregate according to species. Galtsoff (10) extended this work by showing that mixed cells from various tissues of one species will reaggregate according to tissue.The relevance of such data to developing general principles of morphogenesis generated experimental interest in the location and nature of a control mechanism associated with this predictable cellular movement and interaction. The accumulated facts from the classic studies of Holtfreter (17,18)

Macroscopic and histological parameters are considered in an analysis of bone formation in the supraorbital region of macaques (Macaco mulatta), baboons (Papio cynocephalus artubis), and chimpanzees (Pan troglodytes verus). Results indicate that postnatal osteogenesis of the supraorbital segment of the frontal bone in these primates occurs as a cyclic phenomenon that coincides with dental eruption patterns.

An analysis of skulls from several primate species shows that a “worm‐track” surface pattern, first identified in the brow region in fossil adult hominids and subsequently in olive baboons, chimpanzees, and macaques, is also present in numerous other species. Fine cancellous bone and its attendant vermiculate surface pattern have been observed in subadult and adult gelada baboons, gibbons, gorillas, and orangutans as well as in modern Homo sapiens and several Plio‐Pleistocene fossil hominids. In contemporary primates, fine cancellous bone has been identified not only in the brow region, but also along the zygomatic arch, on the pterygoid plates, on the maxilla, along the temporal line, on the mastoid process, and in the region of inion. Given the widespread distribution of this trait, caution is advised when using it as a diagnostic indicator of the evolutionary or functional significance of craniofacial morphology.

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