Fig. 3.

Plot of a plausible energetics model (B) and its components (A) that predicts the estimated optimal body masses and modern distributions of aquatic mammals. Components of energetics model with respect to body mass (A) and comparison of energetics model calculation with stacked modern aquatic mammal body mass distributions and estimated OUwie optima for Sirenia, Odontoceti, and Pinnipedia, respectively (B), are shown. The surplus energy curve predicts the OUwie optima and modern distributions.