Were there mammalian pursuit predators in the tertiary? Dances with wolf avatars

Abstract

Fast-running, long-legged pursuit carnivores are familiar members of the present-day ecosystem, and it has been assumed that extinct large predators took similar ecomorphological roles (i.e., were “wolf avatars”) in past faunas. While these fossil taxa may also have been meat-specialists, we present evidence from limb morphology to show that there was no modern type of pursuit predator until the latest Tertiary. In contrast, ungulates evolved longer legs similar to those of present-day cursorial taxa by the middle Tertiary, some 20 million years earlier. These data suggest the need for the reevaluation of many classical evolutionary stories, not only about assignation of fossil taxa to a wolf-like mode of predatory behavior, but also to issues such as the coevolution of long legs and fast running speeds between predator and prey, and even the implicit assumption that cursorial morphologies are primarily an adaptation for speed. We conclude that evolutionary change in ungulate limb morphologies represents an adaptation to decrease transport costs in association with Tertiary climatic changes and that the present-day predation mode of long distance pursuit is a Plio-Pleistocene phenomenon, related to the development of colder and more arid climates.