Influence of craniofacial morphology on primate paranasal pneumatization.

In order to test the hypothesis that variation in the maxillary sinus volume (MSV) of anthropoid primates is related to skull architecture, a mixed sex sample of adult primate crania covering Hominoidea, Cercopithecoidea and Ceboidea was examined using CT scans. MSV was regressed against basicranial length, using reduced major axis analysis. 2 distinct scaling patterns emerged: while a large MSV seems to be a primitive condition of Anthropoidea, it is clearly reduced in Cercopithecoidea. Although some correlations exist between MSV and different indices of the facial skeleton, they are relatively weak and differed among the 3 groups. A full appreciation of epigenetic factors and the relation of the paranasal sinuses to different cranial components is necessary to highlight the biological role of skull pneumatization.

A longitudinal study of the growth pattern of the maxillary sinus in the pig-tailed macaque (Macaca nemestrina).

The ontogeny of sexual dimorphism in maxillary sinus size in a nonhuman primate was studied longitudinally for a period of 8 years in 25 female and 25 male Macaca nemestrina via lateral cephalograms. The maxillary sinus was traced and its area digitized. The growth of female maxillary sinuses was described with a Gompertz model; the best fit to the male data was obtained by the logistic model. Growth curves and confidence intervals revealed that the sinuses grew in a similar fashion for 3-4 years in both sexes. After this, female sinuses achieved a plateau in their development while male sinuses continued to grow. Confidence intervals suggested that size dimorphism appeared at the age of 6.3 years. Lowess regression indicated growth spurts in both sexes. Females experienced an earlier and smaller spurt than males. Sexual dimorphism in maxillary sinus size seems to represent a combination of differences in velocity and length of growth. This study indicates that growth of the maxillary sinus follows closely the growth in body size. Nevertheless, due to the variation in sinus size in Macaca, it is questionable if body size is the main determinant of maxillary sinus size. It is suggested that Macaca, with its wide geographic range and different environments, is an especially appropriate genus to use to test hypotheses about the evolution of skull pneumatization in primates.

Spontaneous cleft palate in a newborn gorilla (Gorilla gorilla gorilla).

OBJECTIVE: We report the first case of cleft palate in a newborn male gorilla (Gorilla gorilla gorilla). CASE HISTORY AND RESULTS: The full-term infant was born to clinically healthy, wild-caught parents and survived 5 days. Autopsy disclosed a unilateral cleft palate, moderate scalp hemorrhage (birth versus postnatal trauma), cerebral edema, and a sterile fibrin vegetation in the heart. The palate was also shorter and narrower than expected, and the biorbital breadth was reduced; otherwise, growth and development appeared normal. Standard cranial and intraoral radiographs and three-dimensional reconstructions of computerized tomographic (CT) scans provided thorough and noninvasive methods of studying the craniofacial complex and extracranial skeleton. By this technique, major findings were: intact premaxilla, interpremaxillary, and premaxillary/maxillary sutures; intramaxillary cleft with ipsilateral choanal atresia; mildly asymmetric inferior turbinates; and normal nasal septum and vomer. CONCLUSIONS: Except for choanal atresia, cleft palate was not associated with other major craniofacial or extracranial anomalies in this case. Choanal atresia has been observed at times with cleft palate, but to our knowledge, the association has not been reported in nonhuman primates. Cleft palate, with or without cleft lip, has been recognized in a variety of nonhuman primates, including the lemur, marmoset, tamarin, squirrel monkey, and macaque. Some occurrences are spontaneous, while others are syndromic and/or arise from genetic or teratogenic influences. Each mode of presentation is poorly understood in nonhuman primates, but in this case, the absence of relevant environmental or parental history suggests that the occurrence was spontaneous. Anatomic studies of nonhuman primates are particularly valuable when they involve endangered species and will hopefully increase our understanding of the pathogenesis and etiology of congenital disorders, as well as other relationships between nonhuman primates and humans.

Development of the orangutan permanent dentition: assessing patterns and variation in tooth development.

This study examines dental formation and alveolar emergence in a large cross-sectional sample composed primarily of wild-reared orangutans (N = 89) in order to provide information on the development of the permanent dentition in this hominoid and to address questions of variation in individual tooth formation, between teeth and between individuals. All specimens have been radiographed in lateral aspect and stages of crown and root formation recorded for all teeth. The ranges of crown and root formation of I1(1), C1(1), P4(4), M2(2), and M3(3) have been calculated relative to the stage of M1(1) development within a specific tooth quadrant. Then, for each specimen, BMDP scatterplot and nonparametric statistics have been used to graph changes in stages of these teeth relative to M1(1) stages and to examine relationships between pairs of upper and lower dental counterparts and between teeth of each jaw. Results indicate 1) high correlations between upper and lower tooth pairs and between many of the permanent teeth within individuals, 2) a relatively large range of variability in individual tooth development (multistage ranges relative to M1(1)), 3) greater variation in root development at emergence than earlier reports, and 4) evidence of variability within the sequence emergence pattern of the orangutan.

Heterochrony and sexual dimorphism in the pigtailed macaque (Macaca nemestrina).

Somatic growth is not a simple linear process with a constant rate of growth. The most successful attempts to quantify growth as a function of age or size have employed nonlinear techniques. Sexual dimorphism of primate growth, weight vs. age, was examined using nonlinear models with Sirianni and Swindler's ([1985] Growth and Development of the Pigtailed Macaque, Boca Raton, FL: CRC Press) growth data on the pigtailed macaque (Macaca nemestrina). The best fit of several exponential growth models was the Gompertz curve: Weight = a*e-b*e-K*age Different multiple phase models were also fit, where each phase represents a distinct exponential component. The two-phase models proved to be the best (R2 = .0.84 for females, 0.91 for males), suggesting that there are two growth spurts, one in infancy and one at puberty. The timing of the beginning and end of the first spurt is the same in males and females, but the rate, and value of the asymptote for this phase, is greater in males. The timing of the second spurt is earlier, and the rate of growth for this spurt is smaller in females than males. The sexual dimorphism in these species is not a simple rate change, but a complex interaction of timing and rate over the entire period of growth. It would be impossible to separate these entities with a linear, polynomial, or single-phase model of the data. While these data and results complement much of the existing work on adult dimorphism, they also emphasize the vital role that ontogenetic data have in elucidating the underlying evolutionary mechanisms that generate sexual dimorphism.

Longitudinal study of cranial base shape changes in Macaca nemestrina.

The primate cranial base (CB) represents a complex irregular structure even when limited to two dimensions, making it difficult to describe quantitatively using the conventional metrical approach composed of angles and distances. Consequently, a curve-fitting procedure, elliptical Fourier functions (EFF), was utilized, which accurately defines the form of complex two-dimensional morphologies. A longitudinal Macaca nemestrina sample consisting of 14 females and 15 males was utilized. Lateral headfilms, 1 to 8 years, were available (275 headfilms). Because the x-rays were not always taken at precise one-year intervals, a number of headfilms were excluded, which reduced the sample to 181. The CB boundary outline was carefully traced onto acetate sheets and 54 points located. The observed points were digitized and used to compute size-standardized EFF's with 20 harmonics. From each EFF, a set of 150 expected distances to the CB boundary was generated using the centroid as an origin. Superimposition of the CB's on the centroid also provided a detailed picture of the relative shape changes with respect to that center. Statistically significant shape differences were found as a function of age and sexual dimorphism. These age changes consisted of a gradual anteroposterior lengthening with a concomitant narrowing in the superoinferior direction. Specifically, a lengthening of the dorsal clivus and an anterior migration of the hypophyseal fossa could also be discerned. Thus, Fourier descriptors provide a particularly powerful method for documenting, both visually and numerically, the shape changes of complex two dimensional morphologies.

Underbite and the scaling of facial dimensions in colobine monkeys.

This investigation was concerned with the dimensions of the facial skeleton and the incidence of underbite in colobine monkeys. Standard craniofacial dimensions and the notation of the presence or absence of underbite were recorded for skulls of 308 adult, wild-caught colobines belonging to 10 species. Underbite was noted in all species examined, ranging in frequency from 10% in Colobus polykomos to 100% in 2 species of Presbytis. Univariate statistics indicate that species with high frequencies of underbite tend to have shorter, broader maxillary dental arches, shorter faces and rostrums, and longer mandibular dental arches. A multivariate discriminant analysis supported the univariate statistics. Interspecific allometric analysis of facial measurements against a constructed size variable indicated that maxillary dimensions scale in a strongly positive manner in relation to size. However, mandibular dimensions tend to scale isometrically. This pattern of facial scaling indicates that the tendency toward underbite should increase as overall size decreases. This would explain why smaller species have higher frequencies of underbite than larger species and why females often have a higher incidence of underbite than conspecific males. Zingeser has suggested that the high incidence of underbite in colobine and some cebid monkeys is an adaptation to folivory. The results of this study support an alternative hypothesis that the high incidence of underbite in colobine monkeys is related to the pattern of facial scaling with size in combination with relaxed selection on the anterior dentition.

Dental development, skeletal maturation and body weight at birth in pig-tail macaques (Macaca nemestrina).

The degree of maturation of the deciduous dentition and the permanent first molar, as assessed from radiographs, was compared to body weight and carpal development in Macaca nemestrina at birth. All deciduous teeth were present in various stages of development. The permanent molar was represented by 1 to 4 mineralized cusps in 85% of the sample population. A dental maturation score, calculated for each animal, ranged from 12 to 19, with approx. 50% having a score of 17. Compared with the human dentition, that of the neonatal macaque was appreciably more advanced at birth. Carpal development and birth weight were much more variable than dental maturation. Because there appeared to be less variability in tooth development at birth than in the other maturational indicators, tooth formation may offer a better and more accurate estimate of physiological age in this species at this critical time of development.

Human skeletal and dental remains from Lapita sites (1600-500 B.C.) in the Mussau Islands, Melanesia.

The Lapita Cultural Complex, radiometrically dated to between 3,600 and 2,500 B.P., is regarded on archaeological evidence as ancestral to modern Austronesian-speaking cultures of eastern Melanesia and Polynesia. To date, there has been a lack of human skeletal and dental material from Lapita sites; thus, the present sample from Mussau Island, although small, offers an opportunity to present some preliminary observations of their importance to Oceanic prehistory. The present analysis, based mainly on teeth, suggests that the Mussau Island Lapita people had slightly closer affinities with Indonesian than with Melanesian populations. These results correspond well with linguistic and archaeological evidence regarding the origin of the Lapita Cultural Complex.

Canid scavenging/disarticulation sequence of human remains in the Pacific Northwest.

Greater understanding of animal scavenging of human remains can assist forensic science investigators in locating and recovering dispersed skeletal elements, in recognizing damage produced by scavengers, and in making more informed estimates of the postmortem interval. The pattern of skeletal damage can indicate whether the body was scavenged while intact or at some time after other natural processes of disarticulation had begun. This study analyzed thirty partially to fully skeletonized human remains with respect to scavenging at the time of body discovery in order to determine if a patterned consumption sequence existed. The scavengers were primarily coyotes (Canis latrans) and domestic dogs (C. familiaris). Sixteen non-carnivore-scavenged remains were also examined and contrasted with the carnivore-scavenged sample. Observed postmortem intervals from death to recovery ranged from 4 h to 52 months. Results demonstrate that canid scavenging of human remains takes place in sequential stages: Stage 0 = no bony involvement; Stage 1 = ventral thorax damaged and one or both extremities removed; Stage 2 = lower extremity involvement; Stage 3 = only vertebral segments remain articulated; and Stage 4 = total disarticulation. Results revealed a clear correspondence between stages of disarticulation and the postmortem interval.

Tooth mark artifacts and survival of bones in animal scavenged human skeletons.

Animal scavenging activity can result in production of tooth mark artifacts. Such activity can confound interpretation of skeletal material and the identification process. To date, these topics have received limited attention in the forensic science literature. This study discusses the nature of various animal tooth mark artifacts and typical damage to selected bony elements. This study also assesses survivability of various skeletal elements over time. Two major factors that affect which bones are recovered and the amount of damage are circumstances which shelter remains from animals and human population density of the area where the skeleton is recovered.

Evolutionary and morphological significance of the deflecting wrinkle in the lower molars of the Hominoidea.

The deflecting wrinkle is a well-known character state of the lower m2 and M1 of the human dentition, but there is little information regarding its presence in great apes. The deflecting wrinkle is more frequent on M2-3 in all extant pongid genera studied in this paper except Pan paniscus, in which M1 has the highest frequency (16.0%) and in which this wrinkle is absent on M3. In Gorilla, it is absent on M1, with only a low incidence on M2-3. Its greatest frequency in Pongo is always on M2 (20.2%), which is the greatest expression of the trait in the great apes. We interpret the presence of the deflecting wrinkle as an incidental effect and suggest that it represents a plesiomorphic character state in the Hominoidea.

Robust and least-squares orthogonal mapping: methods for the study of cephalofacial form and growth.

A method is presented for the description and analysis of cephalofacial form and growth using two-dimensional coordinate data. The procedure permits the identification of shape differences at specific cephalofacial coordinate locations without reliance upon conventional cephalometric landmarks. The resulting size-standardized coordinates can be analyzed by statistical methods for further data exploration. Two methods of shape transformation--least-squares and robust fitting--are described and compared. An example of the utility of the technique for cephalofacial growth studies is provided.

Molar size sequence in Old World monkeys.

The molar size sequence is examined in a variety of Old World monkeys. The M3 greater than M2 greater than M1 progression is common in the Papionini and Colobinae and rare in the Cercopithecini. The maxillary molars are much more variable in their size relations than the mandibular molars. The findings indicate necessary caution when using the molar size sequence for taxonomic purposes.

The dentition of New Britain West Nakanai Melanesians. VIII. Peopling of the Pacific.

The dental crown morphology and size of 48 male West Nakanai, New Britain, Melanesians is described and compared with other Pacific and Asian dental samples. The West Nakanai dentition is like those of other Melanesians, much less like those of Polynesians and Micronesians, and very dissimilar to teeth of modern and Neolithic Southeast Asians. It is suggested that the origin of the modern Melanesian dental pattern (large but simplified teeth) was probably in Melanesia, not Southeast Asia as the orthodox view of a Hoabinhian-Australmelanesian relation claims.

The sex difference in dimensional communalities in Macaca nemestrina.

Intr-individual correlations for cranial, mandibular and dental measurements made on lateral skull radiographs of Macaca nemestrina were systematically higher in 30 adult females than in 31 adult males by an average of 0.11 to 0.15, depending upon method of computation. Clearly, for the adult pig-tailed monkey as in Homo during both prenatal and postnatal life, developmental and dimensional communalities are systematically higher in the female indicating a general principle or trend.