Three-dimensional geometric morphometric analysis of cranio-facial sexual dimorphism in a Central European sample of known sex

This article presents an approach for estimating the sexual dimorphism of adult crania using three-dimensional geometric morphometric methods. The study sample consisted of 139 crania of known sex (73 males and 66 females) belonging to persons who lived during the first half of the 20th century in Bohemia. The three-dimensional co-ordinates of 82 ecto-cranial landmarks and 39 semi-landmarks covering the midsagittal curve of the cranial vault were digitised using a MicroScribe G2X contact digitiser. The purposes of the investigation were to define the regions of the cranium where sexual dimorphism is most pronounced and to investigate the effectiveness of this method for determining sex from the shape of the cranium. The results demonstrate that it is better to analyse apportionable parts of the cranium rather than the cranium as a whole. Significant sexual differences (significance was determined using multivariate analysis of variance) were noted in the shape of the midsagittal curve of the vault, upper face, the region of the nose, orbits, and palate. No differences were recorded either in the shape of the cranium as a whole or in the regions of the base and the neurocranium. The greatest accuracy in determining sex was found in the region of the upper face (100% of study subjects correctly classified) and the midsagittal curve of the vault (99% of study subjects correctly classified).     

Craniometric measurements of artificial cranial deformations in Eastern European skulls

Standardized lateral cephalograms of eleven skulls with artificial cranial deformations from Eastern Europe and twenty normal skulls from the same population were made, digitized and imported into the AutoCAD 2005 computer program. The x- and y-coordinates of defined measuring points were determined and angle measurements were made. The form difference of the skulls was tested with the Euclidean Distance Matrix Analysis (EDMA) and the difference of the angle measurements were compared statistically using the non-parametric Mann-Whitney test. All deformed skulls belonged to the tabular fronto-occipital type of deformation. The results of the EDMA and the angle measurements indicated significant differences for the neurocranium and the facial cranium in height between the normal and the deformed skulls, but not in the cranial length. It can be concluded that in Eastern Europe one method of cranial molding was used. The deformation of the neurocranium also affected the development of the facial cranium regarding facial height. This may indicate a dependency of the developmental fields of the neurocranium and facial cranium.     

Brief communication: Cranial reconstruction of Dryopithecus.

This paper presents the first three-dimensional reconstruction of the cranium of the European Miocene ape, Dryopithecus. The reconstruction is based on remains collected from Can Llobateres, Spain (CLI 18000; Dryopithecus laietanus), D. fontani (St. Gaudens), and D. brancoi (Kordos and Begun [1997] Am. J. Phys. Anthropol. 103:277-294). Previously unrecognized facial fragments from CLI 18000 were included in the reconstruction. The result shows that Dryopithecus had a relatively short face, with a rather short and well-rounded neurocranium. From the lateral perspective, the face is concave at midface, and on the cranium the temporal lines run parallel to each other without forming a sagittal crest.     

山顶洞101号男性头骨的三维颅面复原

山顶洞101号头骨化石是东亚地区保存最为完整的化石之一,是探讨东亚地区现代人起源的重要研究材料。本文依据数据集中现生人的面部软组织平均分布,提出了计算机三维颅面复原方法,实现了101号头骨生前面貌的预测复原。主要包括三个步骤：首先使用CT完成了101号男性头骨和下颌骨仿制模型的三维重建。然后,利用计算机技术将现生人的面部软组织分布作为101号头骨的面部软组织分布,实现了颅面虚拟复原,并采用手工绘画技巧再现了复原面貌的形态特征。最后,提出了一种基于面部软组织分布和面貌统计形状模型的形态分析方法,实现了颅面复原结果的评估。山顶洞101号头骨的复原面貌具有头部较长、额头前倾、眉弓粗壮等特征,与101号头骨的几何形态基本一致。该技术再现了更新世晚期人类的脑颅及面部的形态特征,为古人类颅面复原的研究提供了技术支持和参考资料。     

A new coordinate system using the orbital axis for morphological analysis of primate skulls

A new coordinate system for primate skulls was defined by the orbital axis and the validity of the system was examined. This system is thought to be equivalent throughout the primates. With the aid of photogrammetry the three-dimensional coordinates of 39 points on the skulls of 479 individuals comprising 54 species including man were accurately measured. The orbital structure is morphologically stable and its axis represents a comparative horizontal. The midsagittal plane and the bilateral symmetry of the cranium are also stable. The morphological stability in angular dimensions is confirmed by a standard deviation smaller than 2.0°. The major evolutionary change in the neurocranium is the inclination of the cranial base from the orbital horizon, and the inclination is related to the neurocranial size. The ear-eye plane is generally inapplicable to the primates, because it is affected by the orbital size and the descent of the auricular part due to the inclination of the cranial base. The clivus line or the vestibular coordinate system is not desirable as the horizontal, either. The evolutionary development of the facial part of the cranium is independent of that of the neurocranium and these two parts are separated by the orbital horizon.     

Technical Note: Virtual reconstruction of KNM‐ER 1813 Homo habilis cranium

A very limiting factor for paleoanthropological studies is the poor state of preservation of the human fossil record, where fragmentation and deformation are considered normal. Although anatomical information can still be gathered from a distorted fossil, such specimens must typically be excluded from advanced morphological and morphometric analyses, thus reducing the fossil sample size and, ultimately, our knowledge of human evolution. In this contribution we provide the first digital reconstruction of the KNM‐ER 1813 Homo habilis cranium. Based on state of‐the‐art three‐dimensional digital modeling and geometric morphometric (GM) methods, the facial portion was aligned to the neurocranium, the overall distortion was removed, and the missing regions were restored. The reconstructed KNM‐ER 1813 allows for an adjustment of the anthropometric measurements gathered on the original fossil. It is suitable for further quantitative studies, such as GM analyses focused on skull morphology or for finite element analysis to explore the mechanics of early Homo feeding behavior and diet. Am J Phys Anthropol 153:154–160, 2014. © 2013 Wiley Periodicals, Inc.     

The phenetic affinities of Rungwecebus kipunji

The kipunji, a recently discovered primate endemic to Tanzania's Southern Highlands and Udzungwa Mountains, was initially referred to the mangabey genus Lophocebus (Cercopithecinae: Papionini), but subsequent molecular analyses showed it to be more closely related to Papio. Its consequent referral to a new genus, Rungwecebus, has met with skepticism among papionin researchers, who have questioned both the robustness of the phylogenetic results and the kipunji's morphological distinctiveness. This circumstance has been exacerbated by the immaturity of the single available specimen (FMNH 187122), an M1-stage juvenile. Therefore, a geometric morphometric analysis of juvenile papionin cranial shape was used to explore the kipunji's phenetic affinities and evaluate morphological support for its separation from Lophocebus. Three-dimensional craniometric landmarks and semi-landmarks were collected on a sample of 124 subadult (dp4-M2 stage) cercopithecid crania. Traditional interlandmark distances were compared and a variety of multivariate statistical shape analyses were performed for the zygomaxillary region (diagnostic in mangabeys) and the cranium as a whole. Raw and size-adjusted interlandmark distances show the kipunji to have a relatively taller, shorter neurocranium and broader face and cranial base than is seen in M1-stage Lophocebus. Principal components and cluster analyses consistently unite the two Lophocebus species but group the kipunji with Cercocebus and/or Macaca. Morphological distances (Mahalanobis D²) between the kipunji and Lophocebus species are comparable to distances between recognized papionin genera. Discriminant function analyses suggest phenetic affinities between the kipunji and Cercocebus/Macaca and do not support the kipunji's classification to Lophocebus or to any other papionin taxon. In canonical plots, the kipunji occupies a region intermediate between macaques and African papionins or groups with Cercocebus, suggesting that it retains basal papionin shape characteristics. In shape comparisons among M1-stage papionins, the kipunji cranium is distinguished from Lophocebus by its relatively unrestricted suborbital fossa, more parasagittally oriented zygomatic arches, and longer auditory tube and from all papionins by its relatively tall, short neurocranium, broad face and cranial base, short nasals, dished nasal profile, and dorsally oriented rostrum. The kipunji is thus a cranially diagnosable phenon with a unique combination of cranial traits that cannot be accommodated within Lophocebus as currently defined. Based upon these results, Rungwecebus appears to be a valid and useful nomen that accurately reflects the morphological diversity of African papionins.     

Basicranial influence on overall cranial shape

This study examines the extent to which the major dimensions of the cranial base (maximum length, maximum breadth, and flexion) interact with brain volume to influence major proportions of the neurocranium and face. A model is presented for developmental interactions that occur during ontogeny between the brain and the cranial base and neurocranium, and between the neurobasicranial complex (NBC) and the face. The model is tested using exocranial and radiographic measurements of adult crania sampled from five geographically and craniometrically diverse populations. The results indicate that while variations in the breadth, length and flexion of the cranial base are mutually independent, only the maximum breadth of the cranial base (POB) has significant effects on overall cranial proportions, largely through its interactions with brain volume which influence NBC breadth. These interactions also have a slight influence on facial shape because NBC width constrains facial width, and because narrow-faced individuals tend to have antero-posteriorly longer faces relative to facial breadth than wide-faced individuals. Finally, the model highlights how integration between the cranial base and the brain may help to account for the developmental basis of some morphological variations such as occipital bunning. Among modern humans, the degree of posterior projection of the occipital bone appears to be a consequence of having a large brain on a relatively narrow cranial base. Occipital buns in Neanderthals, who have wide cranial bases relative to endocranial volume, may not be entirely homologous with the morphology occasionally evident in Homo sapiens.     

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.     

Morphological evolution through integration: a quantitative study of cranial integration in Homo, Pan, Gorilla and Pongo

Morphological integration refers to coordinated variation among traits that are closely related in development and/or function. Patterns of integration can offer important insight into the structural relationship between phenotypic units, providing a framework to address questions about phenotypic evolvability and constraints. Integrative features of the primate cranium have recently become a popular subject of study. However, an important question that still remains under-investigated is: what is the pattern of cranial shape integration among closely related hominoids? To address this question, we conducted a Procrustes-based geometric morphometrics study to quantify and analyze shape covariation patterns between different cranial regions in Homo, Pan, Gorilla and Pongo. A total of fifty-six 3D landmarks were collected on 407 adult individuals. We then sub-divided the landmarks corresponding to cranial units as outlined in the ‘functional matrix hypothesis.’ Sub-dividing the cranium in this manner allowed us to explore patterns of covariation between the face, basicranium and cranial vault, using the two-block partial least squares approach. Our results suggest that integrated shape changes in the hominoid cranium are complex, but that the overall pattern of integration is similar among human and non-human apes. Thus, despite having very distinct morphologies the way in which the face, basicranium and cranial vault covary is shared among these taxa. These results imply that the pattern of cranial integration among hominoids is conserved.     

The influence of experimental deformation on craniofacial development in rats

Cranial deformation was produced experimentally in rats 8 to 40 days old for the purpose of studying the rotation of the craniofacial bones and the modification of the growth rates of the functional cranial components. One hundred and twenty four skulls (65 males and 59 females) were employed, classified as: deformed , deformed-hydrocephalic, sham-operated and controls. A midsagittal diagram was drawn for each skull and the angle subtended by each bone with respect to the vestibular plane was measured. Growth indices were worked out for both the neural skull and the facial skull. Deformation altered the rotation of the parietal, interparietal and basisphenoidal bones and restricted the rotation of the fronto-ethmo-facial complex. Alteration of the longitudinal growth rates of the dorsal and basilar components of the neurocranium and the splanchnocranium produced the persistence of the klinorynchal state.     

An ectocranial lesion on the Middle Pleistocene human cranium from Hulu Cave, Nanjing, China

The earlier Middle Pleistocene human partial cranium from Hulu Cave, Tangshan, Nanjing (Hulu 1) exhibits an ectocranial lesion which covers most of the anterior neurocranium, largely between the temporal lines and extending from the supratoral sulcus to the anterior parietal bone. The endocranial surfaces and the remainder of the cranium (upper facial skeleton, lateral frontal bone, posterior parietal bones, and mid-occipital bone) are normal. The healed lesion exhibits both resorption and the laying down of new bone. Differential diagnosis suggests that the lesion was caused by either trauma (broad compressive trauma, tensile trauma to the scalp, or partial scalp removal) or burning (with damage to scalp and superficial neurocranium). Dietary deficiencies, infection, and neoplastic disorders do not fit the lesion characteristics. The Hulu 1 specimen therefore joins a growing sample of Pleistocene Homo remains with nonfatal and nontrivial disorders.     

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.     

Size, shape, and asymmetry in fossil hominins: the status of the LB1 cranium based on 3D morphometric analyses

The unique set of morphological characteristics of the Liang Bua hominins (Homo floresiensis) has been attributed to explanations as diverse as insular dwarfism and pathological microcephaly. This study examined the relationship between cranial size and shape across a range of hominin and African ape species to test whether or not cranial morphology of LB1 is consistent with the basic pattern of static allometry present in these various taxa. Correlations between size and 3D cranial shape were explored using principal components analysis in shape space and in Procrustes form space. Additionally, patterns of static allometry within both modern humans and Plio-Pleistocene hominins were used to simulate the expected cranial shapes of each group at the size of LB1. These hypothetical specimens were compared to LB1 both visually and statistically. Results of most analyses indicated that LB1 best fits predictions for a small specimen of fossil Homo but not for a small modern human. This was especially true for analyses of neurocranial landmarks. Results from the whole cranium were less clear about the specific affinities of LB1, but, importantly, demonstrated that aspects of facial morphology associated with smaller size converge on modern human morphology. This suggests that facial similarities between LB1 and anatomically modern humans may not be indicative of a close relationship. Landmark data collected from this study were also used to test the degree of cranial asymmetry in LB1. These comparisons indicated that the cranium is fairly asymmetrical, but within the range of asymmetry exhibited by modern humans and all extant African ape species. Compared to other fossil specimens, the degree of asymmetry in LB1 is moderate and readily explained by the taphonomic processes to which all fossils are subject. Taken together, these findings suggest that H. floresiensis was most likely the diminutive descendant of a species of archaic Homo, although the details of this evolutionary history remain obscure.     

Hawaiian craniofacial morphometrics: Average Mokapuan skull,artificial cranial deformation,and the “rocker” mandible

Craniofacial morphology and cultural cranial deformation were analyzed by the computer morphometric system in 79 adult Hawaiian skulls from Mokapu, Oahu. The average Hawaiian male was large, but similar in shape to the female. Both were larger than the present Caucasian, showed a greater dental protrusion, and possessed a larger ANB angle, flatter cranial base, and larger facial heights. Correlations in Hawaiian craniofacial structure were found between an increasing mandibular plane angle and (1) shorter posterior facial height, (2) larger gonial angle, (3) larger cranial base angle, and (4) smaller SNA and SNB angles. Of the 79 skulls studied, 8. 9% were found to have severe head molding or intentional cranial deformation. Significant statistical differences between the molded group and the nonmolded group are, in decreasing significance: (1) larger upper face height, (2) smaller glabella to occiput distance, and (3) increased lower face height with deformation. The morphometric differences were readily seen by graphic comparison between groups. It is postulated that external forces to the neurocranium result in redirection of the growth vectors in the neurocranial functional matrix, including the cranial base, and secondarily, to the orofacial functional matrix. There is a possibility that the cranial deformation is a retention of the normal birth molding changes. The Polynesian “rocker jaw” was found in 81% to 95% of this populace. This mandibular form occurs only with attainment of adult stature and craniofacial form. This data agrees with the hypothesis that mandibular form is modified by the physical forces present and their direction in the orofacial functional matrix.     

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。     

Pathogenesis of encephaloschisis in retinoic-acid-treated hamster embryos I: a morphometric study of the craniofacial structures

The severity of the developmental disorders of the paraxial mesoderm and neuroectoderm must objectively be compared to determine which of the two structures is more deeply involved in the pathogenesis of encephaloschisis. In the present study, hamster fetuses were obtained from dams that had been treated with retinoic acid, and divided into two groups: fetuses with encephaloschisis and those without apparent external malformations in the cranium and face. Mid-sagittal serial sections of the head were prepared, histologically processed, and utilized for the reconstruction of the profile of the head structures. Using this reconstructed profile, we measured the length of the skull base bone structures (basisphenoid and basiocciput), which develop from the paraxial mesoderm, brain structures (mesencephalon and metencephalon), which develop from the neuroectoderm, and facial bone structures (nasal septum and hard palate), which develop from cephalic neural crest cells. The measured length of each structure was compared between the treated and control groups. It was found that treatment with retinoic acid resulted in significantly (P < 0.05) shortened lengths of the skull base bone structures both in fetuses with encephaloschisis and those without apparent external malformations in the cranium and face. In the brain structure of fetuses without encephaloschisis, as well as in the facial bone structures, however, this shortness was not observed. These results suggest that developmental disorders in the paraxial mesoderm may play an important role in the pathogenesis of encephaloschisis.     

The Effect of Dietary Adaption on Cranial Morphological Integration in Capuchins (Order Primates,Genus Cebus)

A fundamental challenge of morphology is to identify the underlying evolutionary and developmental mechanisms leading to correlated phenotypic characters. Patterns and magnitudes of morphological integration and their association with environmental variables are essential for understanding the evolution of complex phenotypes, yet the nature of the relevant selective pressures remains poorly understood. In this study, the adaptive significance of morphological integration was evaluated through the association between feeding mechanics, ingestive behavior and craniofacial variation. Five capuchin species were examined, Cebus apella sensu stricto, Cebus libidinosus, Cebus nigritus, Cebus olivaceus and Cebus albifrons. Twenty three-dimensional landmarks were chosen to sample facial regions experiencing high strains during feeding, characteristics affecting muscular mechanical advantage and basicranial regions. Integration structure and magnitude between and within the oral and zygomatic subunits, between and within blocks maximizing modularity and within the face, the basicranium and the cranium were examined using partial-least squares, eigenvalue variance, integration indices compared inter-specifically at a common level of sampled population variance and cluster analyses. Results are consistent with previous findings reporting a relative constancy of facial and cranial correlation patterns across mammals, while covariance magnitudes vary. Results further suggest that food material properties structure integration among functionally-linked facial elements and possibly integration between the face and the basicranium. Hard-object-feeding capuchins, especially C.apella s.s., whose faces experience particularly high biomechanical loads are characterized by higher facial and cranial integration especially compared to C.albifrons, likely because morphotypes compromising feeding performance are selected against in species relying on obdurate fallback foods. This is the first study to report a link between food material properties and facial and cranial integration. Furthermore, results do not identify the consistent presence of cranial modules yielding support to suggestions that despite the distinct embryological imprints of its elements the cranium of placental mammals is not characterized by a modular architecture.