Dental caries in the fossil record: a window to the evolution of dietary plasticity in an extinct bear

Borja Figueirido,Blaine W Schubert,Francisco J Pastor,Aline A Neves,Francisco Serrano,Aisling B Farrell,Alejandro Romero,Alejandro Pérez-Ramos

doi:10.1038/s41598-017-18116-0

Abstract

During the late Pleistocene of North America (≈36,000 to 10,000 years ago), saber-toothed cats, American lions, dire wolves, and coyotes competed for prey resources at Rancho La Brea (RLB). Despite the fact that the giant short-faced bear (Arctodus simus) was the largest land carnivoran present in the fauna, there is no evidence that it competed with these other carnivores for prey at the site. Here, for the first time, we report carious lesions preserved in specimens of A. simus, recovered from RLB. Our results suggest that the population of A. simus from RLB was more omnivorous than the highly carnivorous populations from the Northwest. This dietary variation may be a consequence of different competitive pressures.

Highlights

Unbalanced predator-prey densities during the Late Pleistocene of North America (≈36,000 to 10,000 years ago) resulted in more carcass encounters among large predatory mammals triggering kleptoparasitism and severe competition over kills[1,2,3]
There is not any evidence of bias favoring the preservation of pathological specimens at Rancho La Brea (RLB), because the ‘carnivore trap’ idea entails that carnivores were attracted by prey-dying herbivores, and the remains of Arctodus at RLB are substantially sparse compared to other hypercarnivores such as Smilodon fatalis or Canis latrans
The pathologies found in A. simus teeth from RLB have similar locations and morphology to those observed in living bear species –i.e., in specific areas across teeth at regular intervals (Supplementary Figs S1 and S3), which differentiates post-mortem breakage from taphonomic processes

Summary

Introduction

Unbalanced predator-prey densities during the Late Pleistocene of North America (≈36,000 to 10,000 years ago) resulted in more carcass encounters among large predatory mammals triggering kleptoparasitism and severe competition over kills[1,2,3]. Other large carnivorans less represented, include the ‘short-faced’ bear (Arctodus simus), the American lion (Panthera atrox) and the ‘scimitar-toothed’ sabertooth (Homotherium serum)[10]. We report the first pathological evidence in A. simus teeth preserved at RLB and we present a large dataset of living bear species from different North American populations affected with similar dental defects. We hypothesize that different competitive pressures may explain this dietary variation between both populations of this emblematic species of the North American megafauna. This may represent evidence that the increase of the extension in the Laurentide and Cordilleran ice-sheets during the middle and late Wisconsinan isolated both populations of Arctodus that were adapted to feed on extremely www.nature.com/scientificreports/. Our findings suggest that both climatic change and local competition among ecologically interacting species are important mechanisms driving biodiversity changes at a global scale

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