Life-history correlates of enamel microstructure in cebidae (Platyrrhini, Primates).

Previous studies have examined tooth eruption as it relates intrinsically to body mass, brain mass, and other life history variables, and extrinsically to ecological factors (e.g., age at foraging independence, environmental risk aversion, and maternal investment). Different models have been explored wherein each of these variables impacts ontogeny. However, anthropoid and strepsirhine primates exhibit interesting differences in the relationships of these ecological and life history variables with tooth eruption. Moreover, interactions between ecological variables and dental tissue growth have only been explored in the lemurs. This study examines dental microstructure of the New World monkey family, Cebidae, to provide further insight into forces influencing the evolution of primate dental ontogeny. The Cebidae were chosen because they are a diverse group which is distinct in ecology and phylogeny from the better known catarrhines of the Old World. Using phylogenetic generalized least squares analyses (PGLS), we test whether brain mass, body mass, or the three above-mentioned ecological variables have stronger correlations with enamel growth. Results show that ecological factors have stronger relationships with cebid dental growth rates than brain or body mass. Foraging independence has the most impact on overall enamel growth as it has the strongest correlation with enamel extension rates. However, another estimate of enamel growth, rate of secretion, has the highest correlation with maternal investment. Our results suggest that an overarching ecological model encompassing the three current ecological hypotheses is needed to further understand the evolution of dental ontogeny within primates.

Interação mãe-filhote em macacos-aranha (Ateles paniscus)

As teorias sobre a relação mãe-filhote em primatas não humanos atribuem à mãe um papel importante e decisivo no desenvolvimento do filhote. Aos poucos, com seu desenvolvimento motor e o aumento da curiosidade pelo ambiente e pelos outros membros do grupo, o filhote vai se afastando da mãe e aprendendo a sobreviver sozinho, embora continue demandando seus cuidados. Com isso, o investimento parental vai tornando-se progressivamente menos necessário, e a mãe redireciona sua energia para outras atividades. O conflito surge no momento em que a mãe e o filhote passam a ter interesses diferentes em relação ao cuidado que ela deve dedicar a ele. O presente trabalho tem o objetivo de analisar o processo de independência do filhote de macacos-aranha (Ateles paniscus), uma espécie de macaco do Novo Mundo pouco estudada. Foram observados quatro filhotes machos e quatro fêmeas, durante os dois primeiros anos de vida. As observações, totalizando 327 horas, foram feitas no Parque Zoológico de São Paulo. Constatou-se uma diminuição gradativa no contato mãe-filhote. A posição Em Contato passou de 100 por cento - 91 por cento no primeiro semestre de vida para 50 por cento no final do primeiro ano. Este é um ritmo lento de desenvolvimento em comparação com macacos-do-Velho-Mundo. Macacos rhesus, por sua vez, atingem índices comparáveis no quinto mês de vida. A lentidão do desenvolvimento pode estar associada a espécies árboreas e um rápido desenvolvimento infantil, a espécies terrestres. O perigo de quedas é grande e o filhote pode morrer se cair de uma altura de cinco metros ou mais (AU)

Desenvolvimento comportamental do Muriqui (Brachyteles arachnoides) na Estaçäo Ecológica de Caratinga, Minas Gerais / Behavioral development of the young muriqui (Brachyteles arachnoides) at the Biological Station of Caratinga, Minas Gerais

Filhotes primatas nascem relativamente desprotegidos, necessitando de cuidados de um indivíduo adulto para garantir sua sobrevivência até estarem aptos a manterem-se sozinhos. As mäes representam o seu primeiro e mais intenso vínculo social. Porém, com o passar do tempo, os filhotes väo se afastando dela, aprendendo a manterem-se sozinhos. Durante o desenvolvimento, as habilidades motoras e sociais se alteram, capacitando-os a desenvolver atividades cada vez mais complexas. Esta auto-suficiência altera a interaçäo mäe-filhote quanto ao interesse pela manutençäo do relacionamento. A presente pesquisa teve como objetivo estudar o processo de independência do filhote muriqui(Brachyteles arachnoides), espécie de primata do Novo Mundo endêmica da Mata Atlântica. Foram observados 29 díades mäe-filhote durante os três primeiros anos de vida dos infantes, nos períodos de agosto/1989 a março/1990 e junho/1994 a junho/1995. As observaçöes foram coletadas através do método de amostragem animal-focal e Ad libitum. Obteve-se 2732 focais resultando em 24900 minutos de observaçäo. Constatou-se uma diminuiçäo gradual do contato mäe-filhote, sendo que apenas no final do primeiro ano de vida, os infantes permaneceram 50 por cento do tempo fora de contato. Por outro lado, o contato esteve diretamente relacionado com a atividade materna, diminuindo mais rapidamente nos episódios de alimentaçäo do que nos de deslocamento e descanso materno. O leite foi o principal alimento dos filhotes até o sexto mês de vida, sendo as folhas o alimento de desmame mais importante após esta idade. A manipulaçäo de objetos pelos filhotes esteve bastante vinculada ao ítem utilizado pelas mäes durante sua alimentaçäo. Os filhotes mostraram índices de sociabilidade superior aos adultos, principalmente em brincadeiras sociais. Foram observadas interaçöes entre os filhotes e os animais adultos e subadultos, tendo sido os filhotes machos mais requisitados. O desenvolvimento dos filhotes muriquis assemelhou-se bastante ao do macaco-aranha e ao dos grandes símios

Cranial growth and growth dimorphism in Ateles geoffroyi.

With the exception of the work of Schultz (1960), cranial growth in Ateles is not well documented. This paper describes the results of a detailed quantitative study of cranial ontogeny in male and female Ateles geoffroyi. Using Euclidean Distance Matrix Analysis (EDMA), local areas of form change due to growth within spider monkey crania are identified. We found substantial change local to the zygomatic region in the face, identified mediolaterally directed changes in the palate, detected relatively larger amounts of change local to the anterior neurocranium compared to the posterior neurocranium, and demonstrate a greater amount of basicranial growth along a mediolateral axis than previously reported. Cranial sexual dimorphism is also examined. A. geoffroyi is noted for being monomorphic, and we found a general similarity between male and female cranial forms at all developmental ages. However, differences in overall cranial size between the sexes were found in the oldest subadult age group but not between male and female adults. This difference suggests that A. geoffroyi females attain their adult cranial form slightly before males and implies a pattern of earlier onset of female maturity relative to males.

Changes in skull components of the squirrel monkey evoked by growth and nutrition: an experimental study.

Twenty weanling 6-month-old male squirrel monkeys were allotted to the following treatments: 1) first control animals were killed at weaning; 2) second control animals were killed when 24 months old; and 3) malnourished animals were fed on a low-protein diet and killed at age 24 months. Lateral and vertical teleradiographies were taken. Growth of the neurocranial and splanchnocranial components were measured by volumetric (size estimators) and morphometric (shape estimators) indices. All facial components grew. The neurocranial components showed a heterogeneous behavior: The anteroneural component remained stable, and the increase of the midneural component was compensated by a decrease in the posteroneural component. Malnutrition affected the growths of 1) the craniofacial complex, 2) the splanchnocranium, and 3) the respiratory and midneural components. Growth influenced skull shape through 1) increases of the splanchnocranium and the midneural component relative to the neurocranium; 2) decreases of the masticatory and optic components relative to the splanchnocranium, and 3) decreases of the anteroneural and posteroneural components relative to the neurocranium. Malnutrition influenced skull shape through the relationship between the anteroneural component and the neurocranium. These results confirmed the existence of functional interrelationships among the cranial components. A new approach to craniological studies is suggested.

A comparative study of neonatal skeletal development in Cebus and other primates.

Comparisons of hand/wrist radiographs of neonatal Cebus albifrons (n = 14) and Cebus apella (n = 4) with those of Saimiri sciureus boliviensis (n = 9) and Macaca mulatta (n = 63) reveal that the cebid monkeys show much less skeletal ossification at birth than macaques. Differences in gestation time alone cannot account for the differences in skeletal maturity at birth in the two groups of monkeys. The skeletal precocity of the newborn macaques indicates that their ossification either begins earlier in gestation or proceeds at a more rapid rate, or both. This, in turn, raises questions about the timing of organogenesis and gestational comparability in cebid and cercopithecid monkeys. The advanced state of ossification seen in macaques at birth is not typical of other groups of anthropoid primates, including Cebus, Saimiri, Pan and Homo, and may represent an ontogenetic specialization.

[Management of individual body weight growth of infant squirrel monkey (Saimiri sciureus) in indoor breeding colony].

We biometrically analyzed the body weight growth data of new-born squirrel monkeys, obtained during the nursing period from 0 to 12 weeks of age. Body weight (y in grams) could be expressed as a function of birth weight (a in grams) and age (x in weeks) by the following equation: y = a + b x, where b indicates growth rate. This equation corresponded significantly with actual growth curves (R2 = 0.96). The frequency distribution of b values was demonstrated to be abnormal distribution. This value was used to judge whether the body weight growth of each monkey was normal or abnormal. The lower control limit (LCL) was calculated by using a linear equation with the b value of 9.07 (M-1.25 x S.D.) and each birth weight. For the monkeys whose body weight was above the LCL during the first three weeks after birth, it was determined whether the frequency of weighings could be reduced from 13 to 7. Using the same animals, no significant difference was detected between the b value estimated from 13 measurements and that estimated from 7 measurements. Thus, from the standpoint of management's policy to save labor, the frequency of weighings could be reduced. A new daily routine has been established in our primate center to save labor by reducing the number of body weighings of the many infant monkeys. In the new program, newborn monkeys whose body weight is above the LCL are weighed only 7 times during the nursing period of 12 weeks, while those whose weight is below the LCL are weighed 8 to 13 times.

Radiographic determination of bone maturation as an aid in predicting chronologic age in the owl monkey (Aotus trivirgatus).

The skeletal development of laboratory-bred owl monkeys (Aotus trivirgatus) ranging from 37 days to 58 months of age was examined radiographically. Femoral length, time of epiphyseal ossification, and fusion of various ossification centers were studied. Chronologic age can be predicted by femoral length determination up to 18 months. Initial ossification of calcaneal, tibial tuberosity, iliac crest, and ischial apophyses occurs between 5.5 and 14 months. Fusion of various secondary ossification centers allows age determination from 7.5 months to 58 months.

Occlusal variation related to soft diet in a nonhuman primate.

Among 43 squirrel monkeys (Saimiri sciureus) raised either on naturally tough or on artificially soft foods, there are significant differences in occlusal features. Animals raised on soft foods show more rotated and displaced teeth, crowded premolars, and absolutely and relatively narrower dental arches. Dietary consistency may be a determinant of occlusal health.

Development and eruption of the mandibular cheek teeth in Cebus albifrons.

The development and eruption of the mandibular cheek teeth of Cebus albifrons is described from a longitudinal series of whole body radiographs. Males are generally ahead of females in both development and eruption times. The dental development and eruption in C. albifrons is intermediate between the smaller New World primates and the larger catarrhines.

Developmental body of composition of the squirrel monkey (Saimiri sciureus).

The longitudinal growth of 69 newborn squirrel monkeys fed control semipurified diets from birth as well as the developmental chemical analysis of 51 carcasses is reported. Males were significantly heavier than females at birth and every age thereafter. Exponential curves fitted to the first two years of life in each sex showed that age and weight were highly correlated (R2 = 0.999). Therefore, the four major carcass components (water, protein, fat and ash) were expressed as a function of a single variable--body weight. Water and protein content were linearly related to body weight over a wide range of growth whereas fat and ash were more variable. Using linear regression analysis, no sex differences were found. On a percentage basis, body fat content was uniformly low (2.7%) at birth and increased to variable levels thereafter. Therefore, the subsequent analyses were done on a fat-free basis. Per cent protein (nitrogen X 6.25) increased from 16.3 at birth to 23.8% at adulthood with water decreasing from 76.4 to 68.9%. The protein:water ratio was 0.213 at birth and increased to an adult value of 0.345. The developmental curves indicated that approximately 70 to 75% of this maturation occurred in the first 3 weeks of life and was completed on, or before, 20 weeks of age. Per cent ash increased significantly from 4.41 at birth to 5.10% at adulthood.

Postnatal growth allometry of the extremities in Cebus albifrons and Cebus apella: a longitudinal and comparative study.

Cebus albifrons and Cebus apella, partially sympatric capuchin monkeys from South America, are known to differ substantially in adult body mass and bodily proportions. C. apella possesses a robust, stocky build in contrast to the more gracile, relatively longer limbed body design of C. alblfrons. Average birth weights and adult body lengths of these two congeners, however, are remarkably similar and do not serve to distinguish them. This study examines longitudinal growth rates and patterns of ontogenetic scaling in the extremities (humerus, radius, hand, femur, tibia, foot) in order to document the nature and magnitude of skeletal changes associated with increasing age and body mass. Our data indicate that the growth rates of the six skeletal components of the limbs differ only slightly and somewhat inconsistently between the two species. Body mass, however, increases at a consistently faster rate in C. apella. Relative to body mass, therefore, the extremities of C. albifrons scale much faster than those of C. apella. This implies that at any given postnatal body mass, C. alblfrons is longer limbed that C. apella. Conversely, C. apella is heavier than C. albifrons at any given limb length or age. We suggest that such differences in body mass distribution are causally related to differences in locomotor behavior and foraging strategies. Specifically, the relatively long-limbed C. albifrons is probably more cursorial and tends to travel longer distances each day than C. apella. C. apella is a much more deliberate quadruped and is also characterized by especially vigorous and powerful foraging and feeding behaviors. We also compare our results to other (mostly cross-sectional) studies of skeletal growth allometry in nonhuman primates.