AFTER THE SABER-TOOTHS: HOW DID COUGARS AND BOBCATS RESPOND TO THE END OF THE ICE AGES?

At the end of the Pleistocene, most of the large mammals vanished from North America, including the predators (such as saber-toothed cats, dire wolves, Ice Age lions, and short-faced bears). Previous studies have shown that the coyotes of the late Pleistocene were bigger and more robustly built to compete for larger prey and then grew smaller and more gracile in the Holocene when their predator competition and large prey both disappeared. How did the surviving large cats respond to this event? We compared cougars (Puma concolor) and bobcats (Lynx rufus) from the late Pleistocene Rancho La Brea asphalt deposits (35-9 ka) to their modern counterparts. The most common bones of these rarely fossilized cats— lower first molar in the jaw, the third metacarpal (MC3) in the front paw, and the third metatarsal (MT3) in the hind foot—were measured with digital calipers. Even though the size range of Pleistocene La Brea specimens were contained within the modern range in most variables, the Pleistocene cougars were significantly larger in the first molar and MC3, although they were significantly smaller in the MT3 (using Hotelling’s T² test of bivariate significance). The Pleistocene and recent bobcats, on the other hand, were not statistically different in their m1, but the Pleistocene bobcat paws and feet were significantly larger, possibly because they had broader lynx-like feet for coping with the snows of the peak glacial. We conclude that Pleistocene cougars were like coyotes in competing with larger competitors for larger prey during the Pleistocene, while bobcats have always specialized on smaller prey and therefore were not affected by the change in the competition or prey during the megafaunal extinction.