Fig. 2. Allometric (scaling) slopes, or b values, from linear regressions of log-transformed variables, for FMR (open circles) and BMR (or SMR for reptiles and lizards; filled circles), compared to the theoretical slopes of 0.67 and 0.75. ^**FMR slope for that taxon differs significantly from 0.75; ^*FMR and BMR for that taxon differ significantly from each other. Numbers of species included in the FMR slope calculations are shown in parentheses. BMR slopes (or SMR slopes for reptiles) are from Kleiber (1975; for mammals, eutherians), Hayssen and Lacy (1985; mammals, eutherians, marsupials), Dawson and Hulbert (1970; marsupials), Lasiewski and Dawson (1967; birds), and Bennett and Dawson (1976; reptiles, lizards).