Scaling of bodily proportions in adult terrestrial mammals.

To model body shape, a data base was constructed for body, forelimb, and hindlimb length, surface area, and girth, each as a function of body weight, in a diversity of mammals. These data were submitted to linear least-squares regression analysis. In addition, data on the partitioning of weight and surface area among the body segments (head-trunk, forelimbs, and hindlimbs) were collected. These data imply a relatively constant partitioning of body weight and surface area among the body segments. The regression parameters and the body segment data were used to build and test a model of bodily proportions. The model consists of three classes of cylinders, each specified by a length and a diameter, representing the three classes of body segments. The parameters of the model were constrained to enforce geometric similarity (constant shape). The model was found to agree reasonably well with an independent subset of the data. It is concluded that adult land mammals do exhibit geometric similarity over a substantial weight range.