Increased aggressive and affiliative display behavior in intrauterine growth restricted baboons.

Background: We hypothesized intrauterine growth restricted offspring (IUGR) demonstrate higher rates of aggression and higher dominance ranks than control (CTR) offspring with normal weight at term; if aggressive behavior is advantageous during resource scarcity, developmental programming may lead to an association between aggression and IUGR.

Methods: We studied 22 group-housed baboons (ages 3-5 years). CTR (male n = 8, female n = 5) mothers ate ad libitum.

The effects of ecology and evolutionary history on robust capuchin morphological diversity.

Recent molecular work has confirmed the long-standing morphological hypothesis that capuchins are comprised of two distinct clades, the gracile (untufted) capuchins (genus Cebus, Erxleben, 1777) and the robust (tufted) capuchins (genus Sapajus Kerr, 1792). In the past, the robust group was treated as a single, undifferentiated and cosmopolitan species, with data from all populations lumped together in morphological and ecological studies, obscuring morphological differences that might exist across this radiation. Genetic evidence suggests that the modern radiation of robust capuchins began diversifying ∼2.

Taxonomy of the Bornean slow loris, with new species Nycticebus kayan (Primates, Lorisidae).

More species of nocturnal primates are now recognized than in the past, because many are cryptic species. Subtle morphological disparities, such as pelage pattern and color variation, vocal cues, and genetics have aided in elucidating the number of diagnosable species in a genus. The slow lorises (genus Nycticebus) once included only two species, but recent taxonomic studies resulted in the description of three additional species; further incompletely explored variability characterizes each of the currently described species.

Feeding and resting postures of wild northern muriquis (Brachyteles hypoxanthus).

Increased body size in Brachyteles has been regarded as an important evolutionary adaptation that allowed a greater reliance on leaves compared to other more frugivorous Atelidae, but its association with muriqui positional behavior and substrate use is still unknown. Here, we present original data on the feeding and resting postures of the northern muriqui (Brachyteles hypoxanthus) and evaluate predictions about the relationships between body size, postural behavior, and substrate use derived from previously published data for other atelids (e.g.

Craniofacial adaptations to tree-gouging among marmosets.

Many primates rely on exudates as dietary items, but comparatively few elicit exudates via tree-gouging. Marmosets are the only haplorhines to extensively utilize this behavior during feeding. Several studies have explored craniofacial adaptations to this behavior, but its morphological correlates are a matter of debate.

The locomotor behavior of Callicebus brunneus and Callicebus torquatus.

This study presents data on the positional behavior of Callicebus torquatus and Callicebus brunneus collected from two different localities in Peru. C. brunneus primarily utilizes short-distance, bounding leaps, while C.

Dentition of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, part 1: quantitative variation.

Analyses of dental variation in geographically restricted, wild populations of primates are extremely rare; however, such data form the best source for models of likely degrees of variation within and between fossil species. Data from dental casts of a geographically restricted population of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, document high levels of dental variability, as measured by coefficients of variation, in a nonsexually dimorphic species, despite its isolation and small population size. Like other primates, moustached tamarins show lower variability in the dimensions of the first molars and increased variability in the dimensions of the final molars in the toothrow.

Evolution of sexual dimorphism in body weight in platyrrhines.

Neotropical primates show a remarkable range in body size, spanning two orders of magnitude from the tiny pygmy marmosets (100 g) to the woolly spider monkeys (11,000+ g). Even among the "smaller" platyrrhines, the range is large. In addition, these primates demonstrate a wide diversity in degrees and directions of sexual dimorphism, in both body size and canine size, from marked positive dimorphism (males larger than females), through monomorphic species, to negative dimorphism.