The development of the vermiculate pattern in the brow region of crania from Indian Knoll, Kentucky

A convoluted brow surface consisting of fine ridges, grooves, and depressions, first identified in ancient fossil hominids and termed the vermiculate pattern (VP), is often low in frequency and of moderate rugosity in crania of anatomically modern human populations. Burials at Indian Knoll, Kentucky, constitute an excellent series for study of the development of the VP, since cranial surfaces are usually well preserved, there are hundreds of immature and mature individuals previously assessed for age, and the VP is high in frequency and rugosity. While a surface pattern resembling a miniature VP is found on the supraorbital surface of all newborns, it is not found on any children age 2 or older. This newborn pattern is probably different in structure and origin from the adult VP. The smooth surface characteristic of children shows evidence of changing to the VP in some adolescents, but the fullest development of the VP occurs in adults. The VP continues to develop in rugosity into the fourth decade, especially in males. These observations indicate that the human VP is different in etiology from somewhat similar brow surfaces found sporadically in immature individuals of some species of nonhuman primates. Statements lumping all vermiculate bone surfaces as "fine cancellous bone" are premature. The human VP development shows no apparent relationship to phases of tooth eruption, as postulated for the appearance of areolar surfaces on brow ridges of immature non-human primates.     

The vermiculate surface pattern in brow ridges of Australopithecines and other very ancient hominids

A convoluted surface pattern of fine ridges, pits, and grooves characterized the brow ridges of Australopithecines and other very ancient fossil hominids. This vermiculate configuration terminated rather abruptly just below the fronto-zygomatic suture in Australopithecines. It was resistant to oriented cracking from weathering or fractures, contrasting with the smooth but structurally oriented zygomatic bone adjacent to it. The pattern apparently developed as individuals matured. The vermiculate pattern seems to have been a feature of brow surface in hominids through much of their identifiable history, despite substantial changes in shape and size of the supraorbital region during human evolution. Limitations on the area of vermiculate surface in Australopithecines suggest that the pattern was associated in some yet undetermined manner with overlying soft tissues. This gives evidence on the cause and functional significance of the vermiculate pattern in Neandertal and modern crania. Problems of describing surfaces as “vermiculate” are raised by observation of elaborations of surface relief on two individuals.     

Structure of bone in the skulls of Neanderthal fossils

Close inspection of surface bone in skulls of Neanderthal man reveals weathering cracks extensive enough in one specimen, La Chapelle-aux-Saints, to allow preliminary analysis of major patterns of orientation and to make inferences about functional relationships of structures. The fine structure of the bone of the brow ridges is very different from the rest of the skull in the two adults examined, having a peculiar vermiculate surface pattern. Weathering cracks do not appear in this region. This indicates that Neanderthal brow ridges are not closely related to normal mechanical forces such as chewing exertion. It may, however, give further support to theories of Neanderthal brow ridges as protection for the eyes. The localized structure of bone often differs from region to region, and offers new possibilities for the analysis of both contemporary and fossil forms.     

Microscopic investigations of areolar brow structure in nonhuman primates and of vermiculate brow structure in hominids

The microscopic structure of bone of the brow region was studied in adult human crania showing the vermiculate surface pattern, and in immature nonhuman primates with an areolar surface. Serial sections from different parts of each brow sampled regional comparability. The human brow regions are basically similar, and differ from those of the other primates. The elevations and depressions of vermiculate surfaces are lamellar bone, usually covered by layers featuring Sharpey's fibers. In contrast, the immature nonhuman primates do not have continuous brow surface layers. Passageways to the interior are closely spaced and separated by irregular projections. These findings indicate that fossil and modern human vermiculate surfaces are not structurally equivalent to areolar brow surfaces observed in some immature nonhuman primates. Reports describing fossil hominid brow regions as composed of 'fine cancellous bone' are probably erroneous and give misleading interpretations of their development and function.     

Growth on Geological Time Scales in the Antarctic Cryptoendolithic Microbial Community

In the process of biogenous weathering of Beacon sandstone in the McMurdo Dry Valleys (Ross Desert), Antarctica, periods of microbial growth, on the time scale of 103-104 years, alternate with sudden exfoliation events. The present study addressed the question of whether microbial growth is continuous between exfoliation events or whether each exfoliation is followed by a period of comparatively rapid growth and then an extended period of steady state. The color intensity (Munsell lightness value) of the rock surface is an indicator of relative age of the crust within the exfoliation cycle, permitting measurement of changes in microbial biomass on a geological time scale. Results indicate that microbial growth is continuous and that exfoliation occurs when the microbial biomass reaches the carrying capacity of the cryptoendolithic habitat.     

A reconsideration of the Fontéchevade fossils

Reconstructions of the Fontéchevade fossils normally depict them as adults without neandertaloid brow ridges. A reconsideration of the size of the frontal sinus, the interorbital breadth, and the frontal squamous thickness of the gracile Fontéchevade I fragment suggests that it could represent either an adolescent or an adult. Similarly, a reconstruction of the Fontéchevade II cranium indicates that it could equally possess or lack a supraorbital torus. Unfortunately, absolute proof of either reconstruction is not available, and therefore, the evolutionary significance of the fossils is uncertain.     

Interpretation of scanning electron microscopic images of abraded forming bone surfaces

The experimental abrasion of forming bone surfaces was conducted so that such surfaces could be characterized. This is particularly important to bone remodeling studies utilizing scanning electron microscope (SEM) imaging of archeological material. Forming surfaces derived from subadult macaque cranial bone were treated by particle abrasion, water abrasion, sliding abrasion, brushing, manual rubbing, weight, exfoliation, chipping and replication. Acetic acid treatments were also performed. The effects of abrasive agents are specific but generally fall into rough (particle and water abrasion) and smooth (sliding abrasion, brushing, rubbing and weight) categories. Protohistoric human and Plio-Pleistocene hominid subadult craniofacial remains were observed with the SEM for comparison with experimental data. The more recent material appeared smooth, probably as a result of specimen preparation procedures using brushes. Surfaces were still interpretable as forming, however, using a more abrasion-resistant feature called intervascular ridging (IVR) described in this study. The IVR pattern is also recognized on the hominid sample, confirming the possibility of performing remodeling studies on abraded fossil material. The abrasion characteristics are somewhat more difficult to classify, however. Abrasion is defined and discussed relative to remodeling studies and taphonomy. The usefulness of the experimental data reported here, however, in paleoenvironmental reconstruction, has yet to be fully realized. Acid and mechanical preparation techniques are briefly addressed. It is concluded that it is possible to characterize a forming surface as abraded according to the findings of this study and that acid, if handled with care, will more likely preserve microanatomical surface detail. It would also be in everyone's interest to employ a less abrasive cleaning regime on archeological specimens.     

Demineralization and Remineralization of Root Surface Caries

Although enamel, cementum and dentin all develop carious lesions in roughly the same manner there are significant differences between enamel and the other two tissues. While early enamel lesions are white, root surface lesions in cementum or dentin are light brown or yellow. The color probably arises from extrinsic stain materials, and it is possible that very early, actively forming lesions are colorless. Cementum and dentin often acquire a hypermineralized surface when first exposed to the oral environment. When caries begins to form, this layer can enlarge or disappear. Therefore, it is possible to have lesions with hypermineralized surface layers, hypomineralized surface layers, or no surface layer. Hypermineralization can also occur deeply within a lesion, probably as a result of remineralization. When this occurs the lumen of the tubules fill with mineral and the crystals within the lesion body become larger. Fluoride is readily taken up by carious root tissues and contributes to remineralization. Remineralization of artificial root surfaces after treatment with monofluorophosphate has been shown. In these lesions much of the newly acquired mineral was found near the surface but some was also found in the lesion body.     

Pathological alterations in the archaic Homo sapiens cranium from Eliye Springs,Kenya

This paper reports on the results of a first computerized tomography (CT)-based study of the Middle Pleistocene matrix-filled skull KNM-ES 11693 from Eliye Springs at Lake Turkana. Ectocranially, the hominid cranium exhibits a remarkable enlargement of the vault symmetrical to the sagittal suture and a porotic surface covering most of the vault. CT analysis further revealed a strong thickening of the cranial vault as well as other relevant aspects. Differential diagnosis suggests that the changes of the Eliye Springs cranium were probably caused by chronic anemia in the childhood or youth of this individual.     

Ossification of the human fetal basicranium

Previous investigations of prenatal development of the human cranium have not identified the sequence of its ossification. The purpose of the present study was to elucidate the pattern of skeletal maturity of the cranial bones in the midsagittal region anterior to the foramen magnum. This study is based upon a radiographic and histochemical investigation of midsagittal tissue blocks of the cranial bases of 73 human fetuses derived from the first half of the prenatal period. A marked regularity in the ossification pattern of the bones in the midsagittal part of the human cranium was observed. Ossification starts in the frontal bone. The sequence in which the next bones ossify is occipital bone, basisphenoid bone, presphenoid bone, and ethmoid bone. The material was divided into 7 maturity stages devised for this analysis. The stages were related to general fetal size (crown-rump length) and to general fetal maturation (composite number of ossified bones in hand and foot). Skeletal development of the median part of the human cranium is not strictly correlated with the size or the stage of general maturation of the fetuses. Knowledge of normal skeletal development is necessary for understanding anomalies of development.     

The earliest evidence for the use of human bone as a tool

We report on the analysis of three human cranial fragments from a Mousterian context at the site of La Quina (France), which show anthropogenic surface modifications. Macroscopic and microscopic analyses, including SEM observation, demonstrate that the modifications visible on one of these fragments are similar to those produced on bone fragments used experimentally to retouch flakes. The microscopic analysis also identified ancient scraping marks, possibly resulting from the cleaning of the skull prior to its breakage and utilisation of a resulting fragment as a tool. The traces of utilisation and the dimensions of this object are compared to those on a sample of 67 bone retouchers found in the same excavation area and layer. Results show that the tool size, as well as the dimensions and location of the utilised area, fall well within the range of variation observed on faunal shaft fragments from La Quina that were used as retouchers. This skull fragment represents the earliest known use of human bone as a raw material and the first reported use of human bone for this purpose by hominins other than modern humans. The two other skull fragments, which probably come from the same individual, also bear anthropogenic surface modifications in the form of percussion, cut, and scraping marks. The deliberate versus unintentional hypotheses for the unusual choice of the bone are presented in light of contextual information, modifications identified on the two skull fragments not used as tools, and data on bone retouchers from the same layer, the same site, and other Mousterian sites.     

大荔颅骨的测量研究

本文报道大荔颅骨的一系列测量数据, 并且将其与中国, 欧洲和非洲的中更新世人类的相应数据进行比较, 发现大荔颅骨的测量数据大多没有超出中国和欧洲/非洲中更新世人的变异范围, 有的与中国中更新世人接近, 有的与欧洲和/或非洲标本更加接近。本文将这些结果与大荔颅骨的与中国古人类共同具有的其他测量和观察特征进行综合考虑, 建议大荔人群属于中国古人类连续进化链中的一员, 并且表现出中国古人类与欧洲和非洲古人类之间基因交流的形态证据。     

A tale of two cities: The genetic mechanisms governing calvarial bone development

The skull bones must grow in a coordinated, three‐dimensional manner to coalesce and form the head and face. Mammalian skull bones have a dual embryonic origin from cranial neural crest cells (CNCC) and paraxial mesoderm (PM) and ossify through intramembranous ossification. The calvarial bones, the bones of the cranium which cover the brain, are derived from the supraorbital arch (SOA) region mesenchyme. The SOA is the site of frontal and parietal bone morphogenesis and primary center of ossification. The objective of this review is to frame our current in vivo understanding of the morphogenesis of the calvarial bones and the gene networks regulating calvarial bone initiation in the SOA mesenchyme.     

A cranial base of Australopithecus robustus from the hanging remnant of Swartkrans, South Africa

SKW 18, a partial hominin cranium recovered from the site of Swartkrans, South Africa, in 1968 is described. It is derived from ex situ breccia of the Hanging Remnant of Member 1, dated to approximately 1.5-1.8 Mya. Although partially encased in breccia, it was refit to the facial fragment SK 52 (Clarke 1977 The Cranium of the Swartkrans Hominid SK 847 and Its Relevance to Human Origins, Ph.D. dissertation, University of the Witwatersrand, Johannesburg), producing the composite cranium SKW 18/SK 52. Subsequent preparation revealed the most complete cranial base attributable to the species Australopithecus robustus. SKW 18 suffered weathering and slight postdepositional distortion, but retains considerable anatomical detail. The composite cranium most likely represents a large, subadult male, based on the incomplete fusion of the spheno-occipital synchondrosis; unerupted third molar; pronounced development of muscular insertions; and large teeth. Cranial base measures of SKW 18 expand the range of values previously recorded for A. robustus. SKW 18 provides information on anatomical features not previously visible in this taxon, and expands our knowledge of morphological variability recognizable in the cranial base. Morphological heterogeneity in the development of the prevertebral and nuchal muscular insertions is likely the result of sexual dimorphism in A. robustus, while differences in cranial base angles and the development of the occipital/marginal sinus drainage system cannot be attributed to size dimorphism.     

Ultrastructural demonstration of cell coat on the cell surfaces of normal human oesophageal epithelium

Synopsis The cell coat in human oesophageal biopsies was studied with Alcian Blue, Ruthenium Red, Safranin O, colloidal iron and the ferrocyanide-osmium tetroxide techniques. Alcianophilic material was found on the cell surface of the basal, prickle cell and functional layers, being most abundant on the superficial cells where it appeared as a continuous coat. In the deeper layers, it tended to have a particulate distribution. Some membrane-coating granules were alcianophilic. Ruthenium Red had a particulate distribution over all cell surfaces. Intercellular debris was also stained. Safranin O produced no staining. Colloidal iron stained the cell coat in a particulate manner. The ferrocyanide-osmium technique showed a uniform filamentous cell coat. The oesophageal epithelial cell coats are, in part, acid mucosubstances which, on the surface cells, may have a protective function.     

Scanning microscopy of the developing vagina in postnatal gerbils

Scanning electron microscopy of postnatally developing gerbil vagina (birth to maturity) shows that longitudinal folds form prior to transverse folds; the process of fold formation is initiated on the dorsal wall and proceeds ventrally. From days 1 to 7 postnatally, the vaginal epithelium is composed of either flat or bulging cells, depending on the vaginal region. The luminal cell surface is covered with uniform stubby microvilli and solitary cilia. Between days 9 and 20, the flat cells with distinct cell boundaries spread toward more proximal areas, leading to the formation of mixed patches of cells with flat or rounded apices. Individual elongated microvilli or tufts of forked microvilli may sprout from their surfaces. Solitary cilia gradually disappear. The transition from immature to mature vaginal epithelium starts around day 20, when individual cells recess below the level of neighboring cells. This process spreads throughout the vagina during the following days, reflecting local changes in the subsurface layers of the epithelium preparatory to exfoliation. Around day 40 the actual exfoliation of the luminal cell layer starts. By this time the surface characteristics of many of the desquamating cells have changed. In addition to microvilli, microridges are being formed. The process of exfoliation is finished by about day 60. The newly appearing cell layers now transform into typical cornified cells of the cycling vaginal epithelium.     

Strain patterns in the horncores, cranial bones and sutures of goats (Capra hircus) during impact loading

The design of bovid horns and skulls for the function of head-to-head fighting has been well studied using mechanical and kinematic analyses, but actual strain measurements from the horncores, cranium and sutures during impact loading have never been made. During in vitro impact loading of one or both horns on the heads of female domestic goats, principal strains were measured from the surfaces of the horncore bases, frontal and parietal bones, and interfrontal and frontoparietal sutures. Impact produced a bending moment at the bases of the horncores, with compressive strains on the posterior surfaces more than doubling the anterior tensile strains. These ratios of compression to tension exceed our predictions (and those in the literature) based on curved beam theory. Principal strains in the cranial bones dropped by as much as 50% crossing the sutures, which acted like springs or hinges to allow cranial bone movement. Sutures also experienced very high strain magnitudes, being more than 10 times greater than those of the surrounding cranial bones. Sutural strains during impact loading of the horns also greatly exceeded the strain levels recorded during mastication in other studies. The decrease in strain between adjacent cranial bones across a suture and the large strains at the sutures indicate that the sutures function as shock absorbers during impact.     

A freeze-fracture study of the body wall of adult, in utero larvae and infective-stage larvae of Trichinella (Nematoda)

The surface layers of the cuticle, the hypodermal membranes and the muscle membranes of the adult, the in utero larvae and the infective-stage larvae of the nematode Trichinella spiralis have been studied by means of the freeze-fracturing technique. The surface of the cuticle of both adults and larvae fractures in ways different from membranes of internal cells. The surface coat on top of the epicuticle is probably the layer that changes antigenically. Reticulate ridges, with associated particles, on the E face of the outer hypodermal membrane of the adult are probably sites of attachment of the hypodermis to the cuticle. Longitudinally arranged ridges, with associated particles, of the outer hypodermal membrane are probably points of attachment to the cuticle in the in utero and infective larvae. Rectilinear arrays of particles are present on the P face of the inner hypodermal membrane and the P face of the muscle membrane adjacent to the hypodermis of adults and larvae and probably play a role in adhesion of the muscle membrane to the hypodermis. Particle-free areas of membrane lie external to the Z bundles of the muscle cell and are similar to the sites of attachment of Z lines in insect muscles.     

Investigating histomorphological variations in human cranial bones through ontogeny

Through ontogeny, human cranial vault bones undergo differentiation in terms of their shape, size and tissue maturation. This differentiation is visible at both the macroscopic and microscopic levels. Preliminary data from a histological and compartmentalisation exploratory analysis of individuals with different ages suggest differences in the modelling and remodelling patterns through ontogeny. Child vault bones are primarily composed of avascular lamellar bone (largely vascularised), late juvenile or adolescent bones present the largest extension of mineralised areas (highly remodelled) and the lowest vascularisation (diploe is highly reduced), and the adult present highly vascularised bone in which the diploe is again largely extended. During childhood, the existence of an avascular lamellar bone promotes the sealing of the cranium bones surfaces whereas adult vault bones seem to become opened ectocranially due to the remodelling. We discuss the possibility that both effects could be related with the head thermoregulation.     

New Australopithecus boisei specimens from east and west Lake Turkana, Kenya

New specimens of Plio-Pleistocene Australopithecus boisei are described from east and west Lake Turkana in Northern Kenya. These include a cranium and partial mandible from deposits close to 2.5 Myr and two partial crania and two mandibles from later horizons. The earlier fossils enable us to decipher, for the first time, some of the in situ evolution of this species within the Turkana Basin. The following are among the important changes in the cranium through time: 1) increase in size and change in shape of the braincase, 2) changes in the meningeal vessel pattern and possibly in the venous drainage pattern, 3) increased flexion of the cranial base and decreased prognathism, and 4) changes in the temporal bone to bring about a more vertical posterior face of the petrous pyramid and the development of a strong articular eminence.