EVOLUTION has never fashioned a lion or wolf the size of an elephant. Nor is it likely to, because such a “super-carnivore” would not be able to run fast enough to catch prey big enough to fuel the energy demands of its enormous body.
“You can only be so big as a mammalian carnivore,” says Chris Carbone of the Institute of Zoology in London. Carbone and his colleagues trawled the literature for estimates of daily energy intakes and expenditures for different-sized species of carnivorous mammals. As they expected, this showed that larger carnivores used more energy, with every doubling of body weight bringing a roughly 1.6-fold rise in energy needs.…
