bears, gray wolves, pumas, and American 

 lions that were nearly twice the size of 

 their African cousins. 



Recently, with the help of graduate stu- 

 dent Fritz Hertel, of the University of Cal- 

 ifornia at Los Angeles, I conducted studies 

 that provided some unexpected findings 

 about the intensity of competition for food 

 among late Pleistocene carnivores. After 

 studying the frequency of broken teeth in 

 modem lions, wolves, and hyenas, we 

 found that, on average, one out of four 

 adults had suffered at least one broken 

 tooth during its lifetime. However, the 

 spotted hyena, a habitual bone-crusher, 

 had a higher frequency of broken teeth, 

 approaching 40 percent. In all species, the 

 most commonly broken teeth were ca- 

 nines (fangs, or eye teeth), followed by in- 

 cisors and premolars toward the front of 

 the mouth and camassials (shearing teeth) 

 and molars along the sides. The increased 

 fracture frequency in hyenas probably re- 

 flects their tendency to consume carcasses 

 more fully, sometimes breaking teeth as 

 they crunch bones. 



These data suggested that tooth break- 



age could be used as an index to reflect the 

 level of competition for food in extinct 

 predators — the hungrier the predators, the 

 more fully a carcass would be devoured, 

 down to and including the marrow-rich 

 bones. To obtain a good estimate of frac- 

 ture frequency in extinct carnivores, we 

 had to look at a lot of teeth. While most 

 fossil sites yield few carnivore teeth, the 

 tar pits of Rancho La Brea are an excep- 

 tion. Here, approximately ten carnivores 

 were lured to their death by each herbivore 

 that was trapped. We were able to examine 

 more than 4,(X)0 teeth of Rancho La Brea 

 carnivores and 550 teeth of dire wolves 

 from two other late Pleistocene sites. AU 

 of the teeth were attached to skuUs or jaws, 

 and we considered teeth to have been bro- 

 ken only if they showed distinct signs of 

 wear after the break occurred. To our sur- 

 prise, the frequency of broken teeth in dire 

 wolves, sabertooths (Smilodon), American 

 lions, and coyotes was three to five times 

 that observed for modem carnivores, in- 

 cluding hyenas. This held true for dire 

 wolves at all three sites and, since we ac- 

 counted for age, was not the result of age 



differences in individuals in the ancient 

 and modern samples. (Bobcats and pumas 

 left few fossil teeth, having been only oc- 

 casional visitors to the tar pits, but none of 

 their teeth were broken.) 



The fossil record of carnivores (teeth 

 included) before 40,000 years ago is mea- 

 ger compared with that of the late Pleis- 

 tocene. Our studies do suggest, however, 

 that for predators such as sabertooths, 

 tooth breakage increased over time; that is, 

 sabertooths that hunted 40,000 years ago 

 had relatively fewer broken teeth than 

 sabertooths that lived 10,000 years ago. 



What could account for tough times in 

 the late Pleistocene that made broken teeth 

 more frequent than seems to have been the 

 case before and since? One possibility is 

 that the tar pits attracted injured or old — 

 and weak-toothed — predators because 

 prey were so vulnerable when mired. 

 Based on their relatively slight tooth wear, 

 however, most of the Uons, dire wolves, 

 sabertooths, and coyotes that died at Ran- 

 cho La Brea were young adults seemingly 

 in the prime of life. A single broken canine 

 or premolar is unlikely to have severely af- 

 fected their ability to hunt. 



I believe the increased tooth breakage 

 in late Pleistocene large predators suggests 

 that at that time, competition for food was 

 more intense than it had been previously 

 and much fiercer than it is today. Having 

 secured a carcass, a carnivore needed to 

 extract as much nourishment from it as 

 possible, a process that led to broken teeth. 

 The extinction of the huge and once abun- 

 dant prey species — American camels, 

 giant sloths, mammoths, and others — 

 could have been the late Pleistocene film- 

 ing point, subjecting the predators to a 

 fight for life that most of them lost. 



Of the four La Brea species we studied 

 that had broken teeth, only the most om- 

 nivorous survived and is today one of the 

 most adaptable of carnivores. The coyote 

 continues to thrive today in habitats as dif- 

 ferent as the wilds of Yellowstone and the 

 backyards of Beverly Hills. 



In a detail of a scene at La Brea 

 some 20,000 years ago, saber- 

 toothed cats drive dire wolves away 

 from the carcass of a horse. Tlie 



asphalt in which so many 



Pleistocene animals became mired 



rarely formed lakes; it usually 



collected in shallow seeps, 



sometimes camouflaged by debris. 



Painting by Mark Halietl 



85 



