Artificial cranial deformation and fossil Australians revisited

Based on cranial characters shared by Homo erectus in Java and Homo sapiens in Australia, Australasia is widely considered the strongest case for a regional origin of modern humans. However, artificial vault deformation has been suggested to be the cause of "archaic" characters such as frontal recession in key fossil Australian crania. We use log-log plots of cranial arc versus chord measurements and we score nonmetric traits often thought to be associated with artificial deformation to make systematic comparisons across groups and deformation types to identify universal consequences of artificial deformation. Based on our large comparative sample (n = 588) apparatus-deformed crania have flatter frontals and occipitals and usually more angulated parietals in the sagittal plane than undeformed crania, regardless of deformation type. Fossil Australian samples exhibit evidence of both undeformed and deformed individuals. The sample from Coobool Creek provides evidence that undeformed individuals had more rounded frontals than recent Australians. However, many individuals from Coobool Creek, Kow Swamp, and Nacurrie exhibit modification of one or more cranial contours. The Kow Swamp individuals in particular plot with deformed crania from all regions. In addition, the frequency of hyperostotic traits such as bregmatic eminence, metopic and sagittal keels in H. sapiens is influenced by both artificial deformation and pathological hypervascularity/hyperostosis. Thus it is unwise to use cranial contours and these nonmetric traits to infer genetic relatedness between Fossil Australians and Indonesian H. erectus.     

Intentional cranial vault deformation and induced changes of the cranial base and face

Three morphologically distinct populations of Peruvian crania (n = 130) were metrically analysed to quantify changes resulting from intentional artificial vault deformation. Two of these samples are artificially deformed (anteroposterior [AP] and circumferential [C] types). Measurements taken from lateral radiographs demonstrated that alternative forms of the cranial base angle (N-S-Ba, planum angle, planum sphenoidale to plane of the clivus and PANG angle, planum sphenoidale to basion-sella plane) and the orbital and OANG angles (orbital roof to plane of the clivus and basion-sella plane, respectively) of both deformed groups increased while the angle S-Ba-O decreased significantly with respect to the undeformed (N) sample. Changes in the AP group are largely due to anteroinferior displacement of the basion-sella plane. Similar changes in group C are amplified by this group's posterosuperior frontal migration. This migration results in a relatively shallow orbit at the orbital plate/frontal squama interface. Unlike the deformation experienced by the external vault plates, the basion-sella plane orientation remains stable with respect to the Frankfort Horizontal. Additionally, nasal region measurements such as maximum nasal aperture breadth and nasal height were largely stable between each deformed group and the undeformed group. However, facial (bimaxillary and bizygomatic), basicranial, cranial, and frontal breadths decreased significantly from group AP to group N to group C. Thus, gross morphological facial changes between each undeformed group and the control group are largely accounted for by dimensional changes in peripheral structures. These results stress the importance of the dynamic interrelationship between the cranial vault and base in the development of the craniofacial complex.     

Sutural effects of fronto-occipital cranial modification

Maya adult crania from the site of Lamanai, Belize provide a retrospective means of examining growth processes in the cranial vault. The Lamanai population practiced fronto-occipital deformation which is found to be significantly associated with premature sagittal synostosis and wormian bones of the lambdoidal suture. The undeformed members of the population also exhibit an abnormally high frequency of sagittal synostosis, but a significantly lower frequency than the deformed sample. It is suggested that the deforming apparatus creates tensile forces on the sagittal suture during the peak period of growth of the parietals, and that these forces might induce an adaptive response important in producing premature sagittal synostosis. The undeformed sample may have an increased congenital risk of sagittal synostosis created by their natural brachycephalic morphology in utero. The frequency patterning of wormian bones suggests a mixture of genetic and environmental causes in which tensile forces may also play a role. © 1996 Wiley-Liss, Inc.     

The influence of artificial cranial vault deformation on the expression of cranial nonmetric traits: its importance in the study of evolutionary relationships

Nonmetric cranial traits have been commonly used in evolutionary relationship studies. They develop during the growth and development of an individual, and for this reason its expression presents different sources of genetic and nongenetic variation. However, the use of these features in evolutionary relationship studies carries the implicit assumption that much of the nonmetric trait variation is essentially genetic. Among the nonheritable factors, cranial vault deformation has been the most studied in human populations. Because of the widespread distribution and elevated rate of artificial cranial vault deformation found in America, and the importance of nonmetric traits in evolutionary relationship studies in this area, the objectives of this paper are as follows: (a) to study the influence of artificial cranial vault deformation on the presence of nonmetric traits within samples of human craniofacial remains; and (b) to establish artificial cranial vault deformation influence on evolutionary relationships between local populations on a regional scale. Our results indicate that artificial cranial vault deformations alter the variation and covariation of metric and nonmetric traits in some samples. Wormian bones, placed in cranial vault sutures, are the most influenced by this factor. However, our results suggest that when all nonmetric traits were used the artificial cranial vault deformation did not influence the basic pattern of variation among samples. The exclusion or inclusion of wormians bones in evolutionary relationships analysis did not modify the results, but using only wormians bones lead to inconsistent results indicating that these traits have little value on these kind of studies.     

Effects of different kinds of cranial deformation on the incidence of wormian bones

Researchers have debated whether the presence and frequency of wormian bones (sutural bones, supernumerary bones, and ossicles) are attributable to genetic factors, environmental factors, or both. This research examines the effects of many different kinds of cranial deformation on the incidence of wormian bones. A sample of 127 deformed and undeformed crania from New World archaeological sites was examined. An undeformed cranial sample (n=35) was compared to the following cranially deformed groups: 1) occipital, 2) lambdoid, 3) annular, 4) fronto-vertico-occipital, 5) parallelo-fronto-occipital, and 6) sagittal synostosis. Three levels of degree of cultural cranial deformation were qualitatively determined. Type and number of wormian bones along each major suture were recorded for each cranium. Group means were analyzed using Kruskal-Wallis one-way ANOVA statistical tests to test the null hypothesis that cranial deformation does not have an effect on wormian bone incidence. Results indicate that all forms of cranial deformation affect the frequency of some types of wormian bones. In particular, all cranially deformed groups exhibited significantly greater frequencies of lambdoid ossicles. Apical, parieto-mastoid, and occipito-mastoid wormian bones also appeared with greater frequency in some groups of culturally deformed crania. Further, varying degrees of cultural deformation all had more lambdoid wormian bones than the undeformed group. These results suggest that wormian bone development in posteriorly placed sutures may be affected more by environmental forces than are their anteriorly placed counterparts.     

Maxillary changes and occlusal traits in crania with artificial fronto-occipital deformation

Artificial fronto-occipital deformation of the cranial vault was typical of pre-Columbian cultures in the central Andean coastal regions. We have studied the influence of this deformation on maxillary and mandibular morphology. Measurements were performed on 86 adult Ancon skulls with anteroposterior deformation. Undeformed skulls from the area of Makatampu (n = 52) were used as the control group. To explore the influence of the deformity on occlusion, the skulls were categorized using the Angle classification and the alignment of the interincisor midline. In the group of deformed skulls, there was an increase in lateral growth of the vault and of the base of the skull (P < 0.001), giving rise to a greater interpterygoid width of the maxilla (P < 0.001), and an increase in the transverse diameter of the palatal vault. The mandible presented an increase in the length of the rami (P < 0.001) and in the intercondylar width, with no alteration of mandibular length. The deformed skulls had normal (class I) occlusion, with no displacement of the midline. The difference in the asymmetry index between the two groups was not statistically significant. Artificial fronto-occipital deformation of the cranial vault provoked compensatory lateral expansion of the base that was correlated with the transverse development of the maxilla and mandible. Occlusion and sagittal intermaxillary position were not affected by the cranial deformity. These results provide evidence of the integration between the neurocranium and the viscerocranium in craniofacial development, and support the hypothesis of a compensatory effect of function.     

Test of the relationship between sutural ossicles and cultural cranial deformation: Results from Hawikuh,New Mexico

A number of researchers have hypothesized that the biomechanical forces associated with cultural cranial deformation can influence the formation of sutural ossicles. However, it is still difficult to make definitive conclusions about this relationship because the effects appear to be quite weak, and contradictory results have been obtained when specific sutures and deformation types are compared across studies. This research retests the hypothesis using a single archeological sample of lamdoidally deformed, occipitally deformed, and undeformed crania from Hawikuh, New Mexico (AD 1300–1680). Our results show no significant difference in either the prevalence or number of ossicles between deformed and undeformed crania, suggesting that the abnormal strains generated by cranial shape modification during infancy are not a factor in ossicle development for this population. One significant relationship was detected at the right lambdoid suture in crania with asymmetrical occipital deformation. Crania that were more deformed on the left side showed greater numbers of ossicles on the right side, but the effect was small. Furthermore, the relationship may well reflect a sampling error, due to the small number of crania with greater left side deformation and scorable right side lambdoid ossicles (n = 11). Although it is possible that forms of cranial deformation other than the posterior tabular types examined here may affect ossicle expression, our review of the literature suggests that the relationship in humans is complex and incompletely understood at this time. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Sutural complexity in artificially deformed human (Homo sapiens) crania.

The pattern of complexity of cranial sutures is highly variable both among and within species. Intentional cranial vault deformation in human populations provides a controlled natural experiment by which we were able to quantify aspects of sutural complexity and examine the relationship between sutural patterns and mechanical loading. Measures of sutural complexity (interdigitation, number, and size of sutural bones) were quantified from digitized tracings of 13 sutures and compared among three groups of crania (n = 70) from pre-European contact Peru. These groups represent sample populations deformed in 1) anteroposterior (AP) and 2) circumferential (C) directions and 3) an undeformed population. Intergroup comparisons show few differences in degree or asymmetry of sutural interdigitation. In the few comparisons which show differences, the C group is always more interdigitated than the other two while the AP group has more sutural bones. The sutures surrounding the temporal bone (sphenotemporal, occipitotemporal, and temporoparietal) most frequently show significant differences among groups. These differences are related to the more extreme binding of C type deformation and are consistent with hypothesized increases in tension at coronally oriented sutures in this group. The larger number of sutural bones in the AP group is consistent with the general broadening of the cranium in this group and with experimental evidence indicating the development of ossicles in areas of tension. We suggest that so few changes in sutural complexity occurred either because the magnitude of the growth vectors, unlike their direction, is not substantially altered or because mechanisms other than sutural growth modification are responsible for producing the altered vault shapes. In addition, the presence of fontanelles in the infant skulls during binding and the static nature of the binding may have contributed to the similarity in complexity among groups.     

The influence of experimental deformation on neurocranial Wormian bones in rats

Two hundred and twenty crania of Wistar rats were experimentally deformed. The growth of the anterior vault was restricted in one subgroup and the growth of the posterior vault was restricted in the second subgroup. Seventy-seven deformed animals survived up to the thirtieth day of age and were sacrificed. Both subgroups were compared with each other as well as with 37 surviving sham-operated animals and 51 controls, all samples being 30 days of age (group A). Additionally, 33 normal crania of animals sacrificed at 1, 10 and 20 days as well as 19 deformed crania of 10 and 20 days old were observed (group B). Chi-square and Z tests were employed. Wormian bones found in the skulls of normal growing rats apparently represent an epigenetic polymorphism. Higher frequencies of wormian bones were found in deformed crania than in sham-operated ones and controls. Experimental deformation may be an extra-genetic factor that affects the normal genetic expression of wormian bones. This concept is relevant to studies of human population differences based on discontinuous cranial traits.     

Cranial discrete traits in the middle pleistocene humans from Sima de los Huesos (Sierra de Atapuerca, Spain). Does hypostosis represent any increase in "ontogenetic stress" along the Neanderthal lineage?

Cranial discrete traits may be regarded as markers of dynamic responses to general and local perturbations of the morphogenetic pattern, particularly when they are viewed and examined in terms of hypostosis vs. hyperostosis. There are indications, in fact, that the variation between these two opposite conditions relates to mechanical stress suffered by the bony structures during early stages of growth and development. In a previous comparison between Neanderthals and modern humans, variable degrees and contrasting distribution patterns of hypostosis were found [Manzi et al. (1996), JHE30: 511-527]. In the present paper, the occurrence, expression and cranial distribution of 20 hypo-hyperostotic traits are examined in the Middle Pleistocene sample from Atapuerca - Sima de los Huesos (Spain), with the principal aim being to test whether or not the degree of cranial hypostosis increases during the evolution of the Neanderthals. Other Middle Pleistocene representatives of the genus Homo (Kabwe and Petralona), the Italian Neanderthals, and a large recent European sample are also considered. A general consistency between the gradual appearance and stabilization of the Neanderthal cranial features and the results of the present analysis is found and is interpreted as an indication that hypostosis does mark the occurrence of "ontogenetic stress". As suggested more than half a century ago by S. Sergi, an increase in "ontogenetic stress" in the Neanderthal lineage could result from the relationship between intracranial pressures and other (heterochronic) effects produced by the growth of a large brain (encephalization) and the ossification of an archaic (platycephalic) cranial vault.     

Developmental stress and cranial hypostosis by epigenetic trait occurrence and distribution: an exploratory study on the Italian Neandertals

The occurrence and distribution of 35 cranial epigenetic traits in the Italian Neandertals (Saccopastore 1 and 2, Guattari 1) were examined according to morpho-functional cranial regions and with respect to a distinction between hypostosis (i.e., weak osseous development, arrested morphogenesis, retention of infantile features) and hyperostosis (i.e. excess of ossification, not reaching the pathological condition). The results, expressed ashypostotic scores, showed higher levels of hypostosis in these Neandertal specimens than in recent European samples. The highest expressions of hypostotis were observed in those regions of the Neandertal cranium where disequilibrium between skeletal and cerebral growth factors was expected. These results—interpreted as expression of developmental stress—are consistent with a heterochronic interpretation of the development of the Neandertal cranium; namely, a faster ossification of the cranial vault relative to brain growth rates.     

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.     

Variation of minor non-metrical cranial variants in Australian Aborigines

1254 Australian Aboriginal crania from various parts of Australia were classified for 30 minor non-metrical variants. Australia was split into various regions, and using statistical methods which give mean overall measures of difference between regions, some regional differences were found. Of the 30 variants used, it was found that 10 of them accounted for about 90% of the variation, and so much of the discussion was restricted to them. The regional differences in cranial morphology appeared, so far as could be assessed, to culminate in two extreme populations: one in the north and the north-west of the continent, and the other in southeastern Australia. The relationship of these findings to the two main theories on the origin and composition of the Aborigines is discussed. The first considers that the Aborigines represent a homogeneous population with no significant regional variation, and the second, that they are a product of hybridization between two or more racial groups. Based on the cranial data given, and other published work, it is considered that, as yet, we have insufficient evidence to favour one of these theories at the expense of the other.     

Developmental and Genetic Constraints on Neurocranial Globularity: Insights from Analyses of Deformed Skulls and Quantitative Genetics

Neurocranial globularity is one of the few derived traits defining anatomically modern humans. Variations in this trait derive from multiple and complex interactions between portions of the brain and the size and shape of the cranial base, among other factors. Given their evolutionary and functional importance, neurocranial globularity is expected to present high genetic and developmental constraints on their phenotypic expression. Here we applied two independent approaches to investigate both types of constraints. First, we assessed if patterns of morphological integration are conserved or else disrupted on a series of artificially deformed skulls in comparison to non-deformed (ND) ones. Second, after the estimation of the genetic covariance matrix for human skull shape, we explored how neurocranial globularity would respond to putative selective events disrupting the normal morphological patterns. Simulations on these deviations were explicitly set to replicate the artificial deformation patterns in order to compare developmental and genetic constraints under the same biomechanical conditions. In general terms, our results indicate that putative developmental constraints help to preserve some aspects of normal morphological integration even in the deformed skulls. Moreover, we find that the response to selection in neurocranial globularity is pervasive. In other words, induced changes in the vault generate a global response, indicating that departures from normal patterns of neurocranial globularity are genetically constrained. In summary, our combined results suggest that neurocranial globularity behaves as a highly genetic and developmental constrained trait. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Neus Martínez-Abadías and Rolando González-José contributed equally to this work.     

Comparative endocranial vascular changes due to craniosynostosis and artificial cranial deformation

The processes of craniosynostosis (premature fusion of one or more of the calvarial sutures) and artificial cranial deformation are similar since both can alter the shape of the craniofacial complex. Most research exploring these processes has focused on the ectocranium, although it is obvious that these processes also modify the endocranium. Endocranial changes due to either craniosynostosis or artificial cranial deformation have not been as thoroughly examined. Silicone rubber endocasts were made from 11 craniosynostotic archaeologically derived specimens from North and South America. For comparative purposes, endocasts were made from 22 normal and 17 occipitally deformed crania that were archaeologically derived from North and South America. With all samples, middle meningeal vessel patterns and venous sinus impressions were qualitatively and quantitatively analyzed. Depth, width, and convolution of the middle meningeal vessels were recorded, and the direction of vessel branches was noted. Both artificial cranial deformation and craniosynostosis altered the endocranial vasculature. Middle meningeal vessel and venous sinus impressions of the craniosynostotic group differed when compared to both the undeformed and artificially cranially deformed samples. Sinuses traversing under synostosed sutures became wider and deeper. In contrast, sinuses directly underneath the greatest artificial deformational stress were shallower, while there was compensatory enlargement of sinuses further away from the greatest deformational effects. Such compensatory enlargement also was shown by the high incidence of enlarged occipital/marginal sinuses in artificially deformed skulls. Increased intracranial pressure is hypothesized to be the cause of the venous sinus changes found in craniosynostotic individuals. Middle meningeal vessel patterns from craniosynostotic and artificially deformed specimens were similar in that their direction paralleled the direction of altered cranial growth. These findings demonstrate that the endocranial vasculature is developmentally plastic and responds to deformation in a predictable pattern. © 1996 Wiley-Liss, Inc.     

Cranial capacity/cranial base relationships and prediction of vault form: A canonical correlation analysis

Canonical correlation analysis was used to test an hypothesized morphological relationship between vault form and cranial capacity relative to length of the chondrocranium. Ninety-five adult male Czech skulls were measured for vault form expressed as length, width and height of the brain case; the chondrocranium was represented by nasion-basion and basion-opisthion lengths. In terms of explained variation, the first and most important dimension of covariation between vault and chondrocranial variables was size. The second most significant dimension of covariation expressed the hypothesized shape relationships—i.e., overall size being equal, the shorter the chondrocranial base relative to cranial capacity, the shorter and wider the vault. Furthermore, the competing hypothesis that vault form is determined by facial length proved untenable since facial length was predictive of vault shape only when measured as prosthion-basion, a measure that incorporates basal length. When corrected for basal length, facial length is unrelated to vault form. The results are consistent with the assumption that phylogenetic and microevolutionary trends toward brachycephaly in man stem from changes in the relationship between two components of skull growth, the chondrocranial base and the brain.     

Artificial cranial deformation in Pleistocene Australians: the Coobool Creek sample

Several authors have suggested that some Pleistocene Australian crania have been altered by artificial cranial deformation. The large sample from Coobool Creek has featured prominently in this debate. The present study reevaluates the evidence for artificial cranial deformation in this population using both a larger cranial sample and a more comprehensive set of measurements than those used in earlier work on this subject. Additionally, random expectation statistics are used to calculate statistical significance for these examinations. The results of this study agree with prior work indicating that a portion of this sample shows evidence for artificial deformation of the cranial vault. Many Coobool Creek crania display strong shape similarities with a population of known deformed individuals from New Britain. Coobool Creek crania 1, 41, 65, and 66 show the strongest evidence for deformation, but several other individuals from this sample also show clear evidence for culturally manipulated changes in cranial shape. This project provides added support for the argument that at least some Pleistocene Australian groups were practicing artificial cranial deformation.     

Asymmetric vault modification in Hopi crania

Cradleboarding was practiced by numerous prehistoric and historic populations, including the Hopi. In this group, one result of cra-dleboarding was bilateral or asymmetric flattening of the posterior occipital. We test whether cradleboarding had significant effects on the morphology of the cranial vault, cranial base, and face. Additionally, we examine associations between direction of flattening and asymmetric craniofacial growth. A skeletal sample of Hopi from the Old Walpi site includes both nonmodified (N = 43) and modified individuals (N = 39). Three-dimensional coordinates of 53 landmarks were obtained using a diagraph. Thirty-six landmarks were used to define nine finite elements in the cranial vault, cranial base, and face. Finite element scaling was used to compare average nonmodified individuals, with averages of bilaterally, right, and left modified individuals. The significance of variation among “treatment” groups was evaluated using a bootstrap test. Pearson product-moment correlations test the association of asymmetry with direction of modification. Hopi cradleboarding has a significant effect on growth of the cranial vault, but does not affect morphology of the cranial base or face. Bilateral flattening of the cranial vault leads to decreased length and increased width of the cranial vault. Flattening of the right or left cranial vault results in ipsilaterally decreased length and width coupled with a corresponding increased length and width on the contralateral side of the cranial vault. There is a significant correlation of size asymmetry with direction of modification in the cranial vault, but not with size or shape change in the cranial base or face. © 1995 Wiley-Liss, Inc.     

Effects of annular cranial vault modification on the cranial base and face

Artificial modification of the cranial vault was practiced by a number of prehistoric and protohistoric populations, frequently during an infant's first year of life. We test the hypothesis that, in addition to its direct effects on the cranial vault, annular cranial vault modification has a significant indirect effect on cranial base and facial morphology. Two skeletal series from the Pacific Northwest Coast, which include both nonmodified and modified crania, were used: the Kwakiutl (62 nonmodified, 45 modified) and Nootka (28 nonmodified, 20 modified). Three-dimensional coordinates of 53 landmarks were obtained using a diagraph, and 36 landmarks were used to define nine finite elements in the cranial vault, cranial base, and face. Finite element scaling was used to compare average nonmodified and average modified crania, and the significance of the results were evaluated using a bootstrap test. Annular modification of the cranial vault produces significant effects on the morphology of the cranial base and face. Annular modification in the Kwakiutl resulted in restrictions of the cranial vault in the medial-lateral and superior-inferior dimensions and an increase in anterior-posterior growth. Similar dimensional changes are observed in the cranial base. The Kwakiutl face is increased anterior-posteriorly and reduced anterior-laterally to posterior-medially. Similar effects of modification are observed in the Nootka cranial vault and cranial base, though not in the face. These results demonstrate the developmental interdependence of the cranial vault, cranial base, and face. © 1993 Wiley-Liss, Inc.     

Craniofacial suture stenosis: morphologic effects

Craniofacial anomalies, such as Apert's and Crouzon's syndromes, are presumed to be related to premature growth arrest of cranial base growth sites. However, premature growth arrest at cranial vault sutures in animals appears to play a causative role in the development of cranial deformities characteristic of single-suture, or simple, craniosynostosis in humans. To study the possible causative role of cranial vault and other (interface) suture stenoses on the development of craniofacial deformity, a vault suture and an interface suture between the cranial vault and facial skeleton were simultaneously immobilized. Thirty-one New Zealand White rabbits at 9 days of age underwent implantation of dental amalgam growth markers adjacent to cranial vault and facial sutures. In the experimental group (n = 15), methylcyanoacrylate adhesive was applied over the coronal (vault) and frontonasal (interface suture between vault and facial skeleton) sutures to immobilize them. The remaining 16 animals served as sham-treated controls. All animals underwent serial radiographic cephalometry to document growth effects in the cranial vault, cranial base, and facial skeleton. Application of adhesive resulted in statistically significant (p less than 0.05) reduction in growth at the coronal and frontonasal sutures. This was accompanied by an overall significant reduction in neurocranial vault length during the first 30 days of development.(ABSTRACT TRUNCATED AT 250 WORDS)