Skeletal and dental morphology supports diphyletic origin of baboons and mandrills.

Numerous biomolecular studies from the past 20 years have indicated that the large African monkeys Papio, Theropithecus, and Mandrillus have a diphyletic relationship with different species groups of mangabeys. According to the results of these studies, mandrills and drills (Mandrillus) are most closely related to the torquatus-galeritus group of mangabeys placed in the genus Cercocebus, whereas baboons (Papio) and geladas (Theropithecus) are most closely related to the albigena-aterrimus mangabeys, now commonly placed in the genus Lophocebus. However, there has been very little morphological evidence linking mandrills on the one hand and baboons and geladas on the other with different groups of mangabeys. In a study of mangabey locomotion and skeletal anatomy, we have identified features of the postcranial skeleton and the dentition that support the molecular phylogeny and clearly link mandrills with Cercocebus and Papio with Lophocebus. Moreover, the features linking Cercocebus and Mandrillus accord with ecological studies of these species indicating that these two genera are a cryptic clade characterized by unique adaptations for gleaning insects, hard nuts, and seeds from the forest floor.

Posture and support use of Old World monkeys (Cercopithecidae): the influence of foraging strategies, activity patterns, and the spatial distribution of preferred food items.

A common objective in field studies of positional behavior is to establish functional links between locomotion, body size, habitat use, foraging strategies, and maintenance activities. In contrast, there has been relatively little effort to examine posture in a similar, comparative context. Although various studies have shown that particular postures are employed in specific contexts, the theory which could provide the basis for understanding posture on a more general level has not been explicitly stated. This is particularly true for primates lacking specializations such as prehensile tails, claws for clinging, or adaptations for forelimb suspension. Consequently, there are few a priori reasons for predicting postural differences among generalized arboreal quadrupeds. Six sympatric cercopithecid monkeys were studied for 14 months in the Ivory Coast's Tai Forest to determine if more general relationships do exist between posture and other aspects of behavior. The results demonstrate that the postural diversity with these primates can, to varying degrees, be understood within the context of differences in the spatial distribution of preferred food items, activity patterns, support use, and foraging strategies.

Comparative locomotion and habitat use of six monkeys in the Tai Forest, Ivory Coast.

The relationships between locomotion, body size, and habitat use in six sympatric Old World monkeys are examined to test whether the associations found are consistent with those demonstrated in previous studies (Fleagle and Mittermeier [1980] Am. J. Phys. Anthropol. 52:301-314; Gebo and Chapman [1995] Am. J. Phys. Anthropol. 97:49-76). Colobus polykomos, C. badius, C. verus, Cercopithecus diana, C. campbelli, and Cercocebus atys were studied for 14 months in the Ivory Coast's Tai Forest. Analyses reveal that (1) larger monkeys tend to frequent those strata containing the greatest densities of large supports while smaller monkeys are more diverse in their canopy use; (2) high frequencies of leaping are not necessarily confined to the understory, and understory specialists are not necessarily frequent leapers; (3) body size does not consistently predict leaping or climbing frequencies; (4) in general, climbing is more frequent during foraging and leaping is more common during travel; (5) larger supports are used during travel while smaller supports are used during foraging; and (6) larger monkeys do not always use larger supports than do smaller monkeys. Some of the factors contributing to the manner that locomotion, body size, and habitat use are related in cercopithecid monkeys are discussed.

Cercopithecid locomotion, support use, and support availability in the Tai Forest, Ivory Coast.

Habitat heterogeneity is widely theorized to be important in the evolution of Old World monkeys, yet the impact of architecturally distinct forest types on the positional repertoires of African monkeys is largely unknown. As part of a wider project, this study investigates how the locomotor behavior of five sympatric cercopithecids varies in structurally distinct forest areas. Fieldwork took place in the Tai Forest, Ivory Coast, from June 1993 to August 1994. Data were collected on Colobus badius, C. polykomos, C. verus, Cercopithecus diana, and C. campbelli ranging throughout a common forest mosaic. The behavior of adult females was sampled using an instantaneous time point scheme at 3 min time intervals. Vegetative differences within each 100 x 100 m grid cell used by all species were quantified. Further, the relative numbers of different sized substrates at 10 m intervals within the canopy were recorded in each cell sampled. Data indicate that consistency of locomotor behavior across forest types is maintained because most monkeys select the same set of preferred supports in both forest types. The conservative nature of Tai monkey locomotor behavior is discussed within the context of additional proximate and ultimate influences and constraints.