ITERATIVE EVOLUTION OF FELIFORM CARNIVORES IN THE NORTH AMERICAN NEOGENE

While iterative evolution of dirk-toothed feliform carnivores is well known from North American Neogene examples (Hoplophoneus, Barbourofelis, Smilodon) less attention has been drawn to the fact that other feliform ecomorphs show similar patterns of extinction and re-evolution concordant with the dirk-tooths. This suggests a comon response to a single driver that we think is the climactic cyclicity originally described by van der Hammen. The long-legged scimitar-toothed feliforms (Homotherium, Machairodus, Nimravus) show this pattern as do the short-legged forms with a specialized bite (Xenosmilus, Pogonodon). These are the top predators in their respective chronofaunas and their extinction and re-evolution follows closely the extinction and reestablishment of successive large herbivore radiations.