Meeting Abstract

8.4  Thursday, Jan. 3  Postnatal development of the appendicular skeleton in mammals KILBOURNE, Brandon M.; University of Chicago, Chicago, IL bmkilbou@uchicago.edu

Levels of perceived gracility and robustness are a conspicuous characteristic identifying some of the vast diversity within and between the major clades of mammals (�orders� of some authors). Though ontogenetic limb bone allometry has been studied in a few mammalian species, it has not been studied across wide ranges of taxonomic diversity, locomotor specializations, limb postures, or adult body masses. I collected femoral length and circumference data on 19 mammalian species spanning six orders (Cetartiodactyla, Perissodactyla, Carnivora, Proboscidea, Pilosa, and Cingulata) in order to understand ontogenetic limb bone allometry in the context of taxonomy, cursoriality, posture, and adult body size. Femur length was regressed against circumference using a RMA regression to determine ontogenetic femoral allometry. During the ontogeny of mammalian species the femora becomes increasingly gracile. An exception to this trend are large-bodied, graviportal species (e.g., Elephas), wherein the femora exhibit isometry or become more robust during ontogeny. Phylogeny and limb posture have little bearing on the changing proportions of limb bones during ontogeny, whereas adult body mass and locomotor specialization (e.g., graviportality) are more strongly correlated.