POSTCRANIAL ADAPTATIONS FOR CLIMBING IN LORIDAE (PRIMATES)

The Loridae are an arboreal family of small primates that are speciali zed for slow and quiet climbing. This paper examines the relationship between lorid locomotory behaviour and postcranial skeletal morphology . Lorid humeral and femoral diaphyseal geometric cross-sectional prope rties, articular surface areas, and lengths are compared to those prop erties in other small primates with less specialized locomotory behavi our. The comparative sample includes both closely related prosimians a nd more distantly related platyrrhines. Results indicate that lorids h ave greater humeral and femoral diaphyseal rigidity than other quadrup edal primates of similar body size, suggesting that lorid limbs are su bjected to greater forces. Lorids also have relatively larger humeral and femoral articulations, corresponding to field and laboratory obser vations which indicate that lorid joints are highly mobile. In additio n, lorids have long humeri relative to femoral length, and compared to humeral length in less specialized prosimians of similar body mass. L ong humeral length relative to femoral length is interpreted as a clim bing adaptation because similar limb proportions are also seen in many non-primate climbers. Altogether, humeral and femoral diaphyseal cros s-sectional properties, articular surface areas, and lengths comprise a suite of characters which have potential for identifying climbing sp ecialists in the fossil record.