LIMB JOINT SURFACE-AREAS AND THEIR RATIOS IN MALAGASY LEMURS AND OTHER MAMMALS

Surface areas of humeral and femoral heads scale largely as a function of body size. However, differences in the relative sizes of these art icular surfaces are correlated with differential joint mobility and fo rce transmission through fore- and hindlimbs. They can therefore assis t interpretation of the positional behavior of extinct species. In thi s paper, we document variation in ratios of humeral head surface area to femoral head surface area among extant primates and other mammals. We then examine a group of extinct primates: the subfossil lemurs of M adagascar. Many Malagasy lemurs, including some giant extinct species with very long forelimbs and short hindlimbs, have relatively small hu meral heads and large femoral heads. We explore the adaptive implicati ons of this pattern. (C) 1995 Wiley-Liss, Inc.