1Department of Anthropology, University of California, Santa Cruz, 2Department of Anthropology, Modesto College
Saturday All day, Clinch Concourse
Gray langurs (Semnopithecus sp) thrive in a wide range of habitats throughout the Indian subcontinent and have been the focus of numerous studies on social behavior and ecology. Locomotor behavior described by Ripley (1967, 1977) and Grand (1976) was used to analyze “arboreal” and “terrestrial” abilities compared to the sympatric macaques and Presbytis senex; leaping is only one aspect of langur locomotion and includes fast and slow movement, and use of firm, flexible, continuous or discontinuous substrates in canopy or subcanopy. Few anatomical data are available on the langur locomotor system.
Based on whole body dissection this study presents data on the musculo-skeleton of 5 adult male and female langurs. As with other Old World monkeys, langur forelimbs are lighter than hindlimbs relative to total body mass: 11-12% and 20-24%, respectively. The tail is 3.8% of body mass and exceeds body length. However, langurs differ from other monkeys (patas, vervet, macaque) in the distribution of mass within limb segments, for example, the thigh segment is lighter (62% vs 66.5-67%), whereas leg (27% vs 23-25%) and foot segments (11 vs 9-10%) are heavier. Similarly, the langur forelimb has a lighter arm segment and heavier forearm segment. The heavier and longer forearm (brachial index: 108, range 105-114) contributes to effective climbing and grasping, as does the heavier leg and foot segments.
For this relatively large-bodied colobine (9-18 kg) the total configuration of body proportions, segment mass and limb lengths contribute to the locomotor versatility observed under natural conditions.