Scaling of body parts in relation to final adult body mass has been of interest for almost 300 years. However, it has been used quite recently to provide estimates of body mass for extinct species, for example the Woolly Mammoth (Mammuthus primigenius), based solely on isolated bones, mainly of limb origin. This manuscript addresses the discrepancies that appear when one uses different limb bones as predictors of body mass and examines the potential use of rib parameters as a means of improving the assessment of adult body mass in a range of diverse living mammals as well as the extinct Woolly Mammoth. The findings of this study have important implications for furthering our understanding of basic biology, physiology and scaling, as well as potential applications in terms of estimating body mass in the field of forensic science.