Cranial Width Research Articles

Size, shape and development in the evolution of the domestic dog

An explanation for the ubiquitous morphological changes during the evolutionary divergence of the domestic dog (Canis familiaris) from the wolf (Canis lupus) has proven elusive. These changes include size reduction, facial shortening and tooth crowding. The ubiquity of these changes suggests that they are unlikely to be direct products of human selection. In this paper explanation of morphological change is approached through allometric analysis of craniometric data from prehistoric domestic dogs from North America and northern Europe and from recent wild Canis. Results indicate that anterior cranial length dimensions are tightly scaled among all Canis, while the dogs show divergent allometries on cranial width dimensions. These patterns are consistent with previous allometric studies involving modern dog breeds. Morphological patterning in dogs is not reasonably explained solely as a by-product of biomechanical constraints associated with size reduction. Rather, morphology is constrained by developmental boundaries, reflecting heterochronic alterations produced by strong selection for size reduction and modified reproductive strategy. Unique dental allometries of dogs stem from lack of tight developmental integration between dental growth and overall somatic growth. Further analysis should focus on the relationship between ancestral ontogeny and adult morphology in dogs.

Morphological Variation Between Populations of the Brush-Tailed Tree Rat (Conilurus-Penicillatus) in Northern Australia and New-Guinea

Variation in external and cranial morphology was studied in Conilurus penicillatus from six geographical regions. Sexual dimorphism (males being larger than females) in body weight and pes length was noted. Animals from Bathurst and Melville Is were distinct from other regions in that they had shorter ears, pes and head and body lengths, and dark ventral pelage. The two specimens from New Guinea had large bodies and pes, and short ears when compared with Australian animals, but incomplete data and small sample sizes precluded inclusion in the discriminant function analyses of external features. All animals from the Cobourg Peninsula, eastern Northern Territory and islands in the Gulf of Carpentaria were black-tailed. Up to 42% of animals from other populations had white tail tips. Analysis of cranial variables showed that there was a considerable degree of distinctiveness between populations. Skulls from New Guinea, and Bathurst and Melville Is, were particularly distinct from other populations. Upper and lower molar row and M1 were long in specimens from New Guinea and short in specimens from Bathurst and Melville Is. However, nasal length, braincase width and bulla length were long in specimens from Bathurst and Melville Is. Possible barriers to population interchange include bodies of water (e.g. separating Bathurst and Melville is from the mainland, and New Guinea from Australia) and unsuitable habitat in the east Kimberley and East Alligator-Arnhem Plateau regions. It is suggested that C. penicillatus had a wider distribution during periods of more mesic climate in northern Australia than at present and that its present distribution is a result of northward contraction since the postglacial thermal maximum. Taxonomic conclusions of the study are the retention of subspecific status for C. p. randi (New Guinea), C. p. melibius (Bathurst and Melville Is) and C. p. penicillatus (all other populations) but not C. p. hemileucurus (locality of type given as 'North Australia').

Secular Change: Confounding Factor or Causative Factor of Inter-population Differences in Modern Japanese Crania?

Basic statistics on cranial measurements from 15 modern Japanese populations were compiled by the Commission of Anthropological Investigation of Modern Japanese Crania. These data were analyzed in order to evaluate the magnitude of inter-population differences and the influence of secular change on the interpopulation differences. Cranial measurements taken for four populations from the late Edo period were used to estimate the inter-population differences that can be caused by systematic inter-observer measurement errors and by the bias in the sampling. The distance measures based on the measurement items with small intraand inter-observer measurement errors indicate that the inter-population differences in modern Japanese crania are much greater than the differences caused by the measurement error. However, the differences caused by sample bias are as large as some of the inter-population differences. The results of cluster analyses indicate that the influence of secular change can not be ignored. According to the results of discriminant analysis, the key characteristic in determining inter-population difference is maximum cranial breadth. Since secular change is observed in seven out of 13 measurement items with significant inter-population differences, a considerable part of so-called geographic differences among modern Japanese crania is likely to be due to the secular change that took place during the 100 year period required to collect the materials.

Proconsul did not have a tail

This study describes two new sacral specimens of Nacholapithecus kerioi, KNM-BG 42753I and KNM-BG 47687A, from the Aka Aiteputh Formation in Nachola, northern Kenya, excavated in 2002. They are of roughly equal size and are considered to belong to males. When scaled by body mass, the lumbosacral articular surface area of the better preserved specimen, KNM-BG 42753I, is smaller than that in Old World monkeys but similar to that in extant great apes and New World monkeys, as well as Proconsul nyanzae. The relatively narrow dimensions of the first sacral vertebral body in the transverse and sagittal planes are characteristics of N. kerioi and P. nyanzae and similar to those of extant great apes. In N. kerioi, lumbosacral surface area relative to body mass is small. This may simply be an extension of a trend from the previously reported small thoracolumbar vertebrae to the sacrum. ​The first sacral vertebrae of N. kerioi and Epipliopithecus vindobonensis have a higher craniocaudal vertebral body reduction (CVR; a higher CVR indicates a wider cranial width relative to a narrower caudal width), similar to that in Old World monkeys. Old World monkeys have a higher CVR, and usually have three sacral vertebrae, fewer than seen in extant great apes, which have a lower CVR and four to six (sometimes as many as eight) sacral vertebrae. New World monkeys have a lower CVR than Old World monkeys, but generally possess only three sacral vertebrae, and have a large caudal articular surface, which may be related, at least in the Atelidae, to the grasping ability of their tails. The possibility that N. kerioi had only three sacral vertebrae cannot be ruled out, because E. vindobonensis and Old World monkeys, with higher CVRs, have sacra consisting of three sacral vertebrae.

Measurement of weasel body size

Body size of long-tailed weasels (Mustela frenata) and short-tailed weasels (Mustela erminea) collected in northern and central Idaho was indexed using cranial length, zygomatic width, cranial mass, body mass, and body length (total less tail) as size variables. In comparison with the other variables, body length had lower and sometimes nonsignificant correlations with principal component 1 (PC1) scores of principal component analysis, suggesting that its further use as an index of body size for these species is inappropriate. Young males (6–9 months of age) of one or both species, similar in body size to adult females, occurred in all regions sampled. Because body size alone is not a reliable method of separating juvenile males from adult females, specimens identified as male lacking the baculum or tag information independently confirming sex are possibly misclassified.

Head Size in Relation to Schizophrenia and Schizotypy

Cranial breadth and length on DSM-III schizophrenic probands (n = 16) and their nonpsychotic siblings (n = 34) were measured using standard anthropometric calipers. Siblings were divided into those with and those without DSM-III schizotypal personality disorder based on Baron et al.'s Schedule for Schizotypal Personalities interview (1981). These siblings provide controls for prenatal and childhood nutritional status, which could affect head size, and for genetic contributors to head size. Contrary to previous reports (Andreasen et al. 1986; and Pearlson et al. 1989), in the present sample schizophrenic patients did not have smaller heads. The relationship between height and head size for schizophrenic subjects, schizotypal siblings, and nonschizotypal siblings was also examined. As in Andreasen et al. (1986), the regression slope of head size on height was lower in schizophrenic patients than in their siblings, but here this difference was not significant. The data do not support a conjectured relationship between small or dysmorphic head size and schizophrenia or schizotypy.

Hypertelorism Correction in the Young Child

This series reports on 20 patients who underwent orbital hypertelorism correction under 5.3 years of age (average age 3.9 years). The patients were followed an average of 5 years, and six patients were followed in excess of 7 years with clinical and cephalometric parameters. The study demonstrated that the procedure could be safely performed at this age and was aesthetically desirable. There was minimal clinical or cephalometric evidence of skeletal orbital relapse except in three patients, for whom individual explanations are given. During the period of postoperative study, nasomaxillary growth and development proceeded as expected, except in those patients with associated clefting. All patients demonstrated increased cranial width measurements preoperatively and postoperatively, but bigonial and bimastoid measurements were generally within normal range. Excessive resection of nasoglabellar skin at the time of hypertelorism correction appeared to adversely affect nasal development.

Craniometric allometry in the thicktailed bushbabyOtolemur Crassicaudatus

Static adult craniometric allometry was evaluated in a sample of 66Otolemur crassicaudatus skulls (34 males, 32 females). Although cranial measures were equally well correlated to skull length in males and females, there were noteworthy differences in the exponential values between the sexes. These results underlined the need for caution when allometric analyses are based on pooled data. From the cranial allometric analyses it is concluded that the longer the skull, the shorter and the narrower the maxilla, and the broader the bizygomatic distance. Although cranial length increased proportionately to the increase in skull length, the cranial width in females was positively allometric whilst in males it was negatively allometric. Allometric analyses of mandibular dimensions suggest that larger animals will have proportionately longer mandibulae, which will, in turn, be relatively wider across the gonia, yet shallower behind the first molars. It is postulated that the disproportionate widening of the zygomata might be related to the widening across the gonia.

Interspecific allometry of the mandible, dental arch, and molar area in anthropoid primates: Functional morphology of masticatory components

Allometric equations relating the lengths and widths of the mandible and dental arch, and of molar area, were obtained in a wide range of anthropoid primates grouped into four subsets, pongids, cercopithecids, nonmarmoset platyrrhines, and marmosets. Mandibular width is negatively allometric against length across anthropoids but cercopithecids had relatively wider mandibles than nonmarmosets of the same size class. Mandibular length relative to dental arch length was isometric within and between the four groups but dental arch width scaled negatively against all the other dimensions examined in this study, indicating a functional dissociation between the dental arcade and the bony mandible. Molar area showed various scaling patterns relative to mandibular length (isometry) and width (positive). There were no parameters that scaled positively against body weight across groups, except for molar area in cercopithecids (strongly) and nonmarmoset (moderately). Notable functional specializations include relatively long dental arches in cercopithecoids, related to large, elongate bilophodont molars, and the tendency to increase relative jaw length across the range of anthropoid sizes, reflecting negative allometry of the brain (cranial bicondylar width). We caution that various allometry and functional patterns may be masked by generalizing from broad taxonomic comparison involving a large sweep of adaptative patterns.

Medieval Japanese Dogs in Kamakura Zaimokuza Site

Many skeletons of dogs of the Jomon period have been reported in Japan. There is little information, however, regarding medieval dogs. In 1953, the medieval burial site was excavated in Zaimokuza (Kamakura, Kanagawa Pref.). Human skeletons including 556 skulls with many of horses and dogs were unearthed there. These dogs are very important for tracing the phylogeny of the ancient Japanese dog.We examined morphologically eight reconstructed dog skulls (six males and two females) and three other anomalous or injured skulls. The numbers of the dogs at this site was 30, as estimated by the number of lower first molars. Young dogs were rarely found at this site. Although skeletons were well preserved, many skulls were fragmented. One skull seems to have been cut by a sharp instrument such as a Japanese sword. Nearly one-third of human long bones have terminal bite injuries caused by dogs (KOHARA, 1956). They might have been killed by a sword or stick because they were eating human corpses.The maximum cranial length of the Zaimokuza dogs (male: 170-180mm, female: 156-161mm) was longer than that of the Jomon dogs (Tagara dogs). According to the size categories described by HASEBE (1956), male dogs were of the medium type and female dogs were of the medium small type. The latter medieval dog (Kutsukake dog in the mid-sixteenth century) and early modern dogs (Asahinishi dogs and Sannomaru dogs in the seventeenth century) had similar size crania. The size of the Japanese dogs gradually became larger after Jomon period. A similar tendency was observed in North American ancient dogs by HAAG (1948). This tendency of cranial enlargement was considered to be mainly due to evolutionary changes in the Japanese dogs, and not by interbreeding with dogs imported from the other countries. The cranial enlargement continued until the Kamakura period.The depression between the muzzle and the top of the frontal bone, the so-called stop, was slightly smaller than that of the Jomon dogs and was much smaller than that of the recent Shiba dogs. The cranial breadth and the cranial height were smaller than those of the Shiba dogs, but were similar to those in Jomon dogs. The foramen magnum showed a primitive oval form as observed in Jomon dogs. The Zaimokuza dog skeletons were very robust compared with the recent Shiba dogs. Individual variations in size and shape were greater than those in the Jomon dogs.Many of the features of Zaimokuza dogs were similar to those in Jomon dogs, but were different from those of the late medieval and early modern dogs, especially the present Shiba dogs. In contrast to the size enlargement, the cranial proportion of the Japanese dogs was found to have changed mainly after the Kamakura period.

Body condition and population regulation by food resources in moose.

In southwestern Québec, non-harvested moose populations stabilize at a density of ≈0.40 animal·km-2. In an attempt to test population regulation by food resources, we investigated moose body condition near this equilibrium density (0.37) and at 2 lower densities (0.22 and 0.17). Annual population growth rates were evaluated at 4, 18, and 24% respectively. We predicted that moose in the high density area would exhibit growth retardation and poorer body condition, compared to moose in the lower density areas. Measurements of head length, cranial breadth, heart weight, and kidney weight were collected from 443 moose killed during the regular autumn harvesting seasons of 1981 and 1982. There was no indication that body condition was poorer at high moose density, and hence no evidence that foraging conditions were deteriorated. We concluded that food limitation was not sufficient to explain the differences in population growth rates. Predation by wolves and/or black bears is presented as an alternative and testable hypothesis.

Reply to Levinton

Levinton notes that the number of individuals available to my study of patterns in the evolution of Homo erectus is low, especially when cranial base breadth is considered. If measurements of biauricular breadth are related to stratigraphic age of the fossils using linear regression, the slope obtained is small (−1.52). The confidence interval includes zero, and there is no evidence that a real trend is present. At the same time, the .95 interval is large (±26.81), so slopes differing by even a substantial margin cannot be distinguished. Levinton suggests that this negates a claim for stasis, and I agree that there are grounds for doubt. But by his reasoning, a case for stasis can never be established. While it is true that the occurrence of (very small) trends can never be denied, even if an analysis of many fossils shows a zero slope bracketed by narrow confidence limits, surely these “trends” must be dismissed as insignificant. Given such an outcome, a conclusion of no (directional) change would be quite justified.

The human chin and its relationship to mandibular morphology.

This study evaluated the proportion of the external chin (protuberantia mentalia) in relation to the total symphyseal area in normal jaws and those with a diverse morphology. A sample of 60 cases was randomly selected and divided into three groups of 20 each on the basis of normal growth, horizontal growth and vertical growth with an open bite. Tracings of lateral dn frontal radiographs were used to describe general mandibular form and to determine the percentage of external/total symphyseal area. Dental casts were also examined to determine a basal arch form ratio. The results of this study indicate that the amount of bony chin present is related to certain morphologic features of the mandible. The most significant findings illustrate: 1. The chin increases in size as the mandibular type varies from a vertical type, to a normal type, to a horizontal type of growth pattern. 2. With dental "hypofunction" in combination with an exaggerated vertical development of the mandible, a smaller proportion of the protruding chin is present. 3. The chin increases in size as the mandibular basal arch form varies from a tapered shape for the vertical cases to a more square form in the horizontal cases. 4. The degree of lateral ramal flair does not appear to influence the proportion of protruding chin present. Several models have been presented which attempt to explain protuberantia mentalia variation. The evidence in this study supports the concept that mandibular morphology is the result of the action of compensative adaption in a developing structure. There appears to be an implied polygenic influence on symphyseal morphology operating from the cartilaginous cranial base and mandibular basilar bone. This may be manifested in the relative proportion of mandibular basal bone to cranial base width, and to the vector of cranial base growth. The ultimate proportion of the bony chin is viewed to be the result of mandibular adaption to a functional musculoskeletal balance in the craniofacial complex. The extreme variability of chin form in man may be considered to be the result of compensative growth developing in response to the most structurally efficient jaw form, the contiguous soft and hard tissue environment, and the intrinsic genotype of the mandible.

Tables of cranial and orbital measurements, cranial volume, and derived indexes in males and females from 7 days to 20 years of age.

AbstractA series of head measurements were made in both sexes during the growth period from 7 days to 20 years of age. The measurements included head circumference, breadth, length, and height as well as interpupillary distance and the lateral orbital and medial canthal dimensions; all were expressed as means ± standard deviation in centimeters. In addition, cranial volumes were calculated from the three cranial dimensions according to a previosuly validated formula, and various cranial and orbital indexes were determined for all growth stages.The increments of all measurements are greatest during the first 12 months of life. At 1 year of age, the cranial volume has increased by a factor of 2.3 and the head circumference, cranial breadth, length, and height by a factor of 1.4 over that at birth. Subsequently the pace of growth slows; at 5 years of age cranial volume has increased up to a total factor of about 3 while head circumference and the other three cranial measurements have expanded by a factor of about 1.5 over the dimensions at birth. By 20 years of age the cranial volume is about 3.8 times that at birth, and the head circumference and the three principal cranial dimensions have increased by a total factor of about 1.6. Clinical applications of the measurements, cranial volume, and certain indexes are listed.

Factors of human skeletal craniofacial morphology.

Thirty cephalometric measurements representing craniofacial depth, height, and width were obtained from lateral and posterior rediographs of 66 boys, 8 years of age. A multivariate factor analysis was performed on these measurements in an effort to locate specific areas of variability within the craniofacial complex. Twelve uncorrelated factors were extracted which account for 91% of the total variance and these were identified as: 1) retrognathic facial type, 2) anterior dentoalveolar height, 3) maxillary body length, 4) cranial base and facial width, 5) mandibular ramus height, 6) anterior maxillary body height, 7) mandibular length, 8) cranial vault height, 9) vertical position of the condyles, 10) cranial vault and clivus length, 11) bigonial width, and 12) cranial vault width.

Cephalometric analysis of the craniofacial region of the northern Foxe Basin Eskimo.

AbstractPast investigations of the Eskimo have indicated that there are marked morphological differences in the craniofacial skeleton of this relatively isolated ethnic group compared to other ethnic and racial groups. This study, using cephalometric radiography, attempted to characterize the craniofacial phenotype of the Eskimo living in the northern Foxe Basin, Northwest Territories, Canada. Age changes were examined on a cross‐sectional basis with comparisons being made with a Winnipeg Caucasian group.This investigation indicates that the Igloolik Eskimo has a phenotype, established early in life, and is distinct from the Winnipeg group. The overall size of the Eskimo craniofacial complex was significantly larger at three years of age and remained larger through the ages studied. Development of the craniofacial region, however, was fairly similar in rate and direction for both populations.The greatest differences between the Eskimo and Caucasian groups were found in the linear measurements assessing cranial width, facial width, mandibular length, facial height, protrusion of the incisors, chin point development, and nasal morphology. Differences between the two groups in the morphological relationships of the component structures include the angular relationships of the maxilla and nasal bones to the anterior cranial base, the gonial angle of the mandible, and the angle of facial convexity.

A propos des déformations crâniennes artificielles observées au Proche-Orient

Starting from the study of the deformed skulls of Byblos (Lebanon, Chakolithic age) we have reviewed the various regions in the Near East (Egypt, Lebanon, Turkey, etc.) where this custom has been manifested as early as the Neolithic age. The comparison, by means of some statistical tests between undeformed and deformed skulls, allowed us to reveal some modifications such as the reduction of the maximum cranial breadth, the increase of the maximum cranial length, the reduction of the height of the mandibular body, etc. By measuring the depth of depressed areas due to artificial deformation on the skulls of different ages we have remarked that it accentuated progressively as a function of age; from adolescence onwards the traces of depressions diminish appreciably.

The ontogeny and growth of the human tentorium cerebelli.

AbstractThe ontogenetic pattern of the human tentorium cerebelli was reconstructed by analyzing the series of stages through which the tentorium passes in the attainment of maturity. The absolute and relative growth rates were calculated for the maximum cranial breadth, maximum cranial length, and various tentorial dimensions. The relationship between the growth of different parameters was established and expressed mathematically according to Huxley's formula (y = bxk). The growth ratios (k) and constants (b) for different combinations of tentorial and cranial parameters were elicited from logarithmic graphs.

Variation in the Long‐tailed field‐mouse (Apodemus sylvaticus) in south‐west england

Measurements of four skull and five external characters were made on each of 277 specimens of Apodemus sylvaticus (L.) from the two Isles of Scilly (Tresco and St Mary's) on which it occurs and from six localities in mainland Cornwall. The skull characters were greatest length of skull, maxillary tooth row, cranial breadth and length of palatal foramen. Lengths of the pectoral stripe, tail, hindfoot and ear were obtained, as well as the weight of each animal. The age of each individual was assessed by means of a tooth wear character and a regression adjustment was used to bring all the characters to a uniform age class. The adjusted and unadjusted means have been calculated of each character for every locality. The sexes were separate throughout the analysis.The island mice are slightly larger than those from the mainland, the latter forming a fairly homogeneous group. In addition to overall size the most distinctive sign for the Tresco mice is the particularly small pectoral stripe. The St Mary's mice have a long tooth row, large pectoral stripe and large palatal foramen. The females were usually slightly smaller than the males.A canonical analysis was made in an attempt to account for as much variation as possible between groups using a limited number of linear combinations of the original measurements. The greater part of the variance was contained in the first two canonical variates. From these, the populations separated into three groups, i.e. the mainland group, the mice from Tresco and those from St Mary's. The two Scilly Island populations are as distinct from each other as they are from the mainland populations. Separate introductions from different sources and, possibly, slightly different genetic composition of the original immigrants may have accounted, in part, for the divergence shown by these two island stocks. It is not proposed that the island races should be given subspecific status.

Variation in the long-tailed field-mouse (Apodemus sylvaticus (L>)) in the Channel Islands.

Measurements of ten skull characters were made on each of 352 specimens ofApodemus sylvaticus(L.) and 37 specimens ofA. flavicollis(Melch.). The latter were obtained from southern England and the former from five of the Channel Islands, two localities in southern England and one in northern France. The characters were greatest length, greatest width, interorbital breadth, cranial breadth, width of foramen magnum, length of maxillary tooth row, length of palatal foramen, distance between ventro-posterior processes of pterygoids, length of mesopterygoid fossa and minimum distance between first upper molars. The ages of the skulls were ascertained by means of a tooth-wear measurement. A regression adjustment was used to bring all the characters to a uniform age class. The sexes were separate throughout the analyses. The unadjusted and adjusted means have been calculated of each character for every locality. Appreciable variation occurs between the populations examined, with the females slightly smaller than the males but following the same general pattern of variation. An analysis into canonical variates was made with a view to accounting for the largest possible part of the variation between groups using a limited number of linear combinations of the original measurements. Almost all the variance was contained in the first four canonical variates and from these it appeared that the populations separated into three groups. The first contained the mainland mice from Hampshire, Cornwall and Cap Gris Nez, the second those from the Channel Islands and the third the collection ofA. flavicollis.The analysis confirms that in the British IslesA. flavicollisis distinct fromA. sylvaticusand that the Channel Island mice, although larger than the mainlandA. sylvaticus, probably belong to that species. Differences between populations from the Channel Islands are small, although the mice from Herm and Sark are relatively large. It is possible that the Channel Island mice could have been derived from a common stock.