Implications of diet for the extinction of saber-toothed cats and American lions.

Larisa R G Desantis,Peter S Ungar,Jessica R Scott,Blaine W Schubert,Anjali Goswami

doi:10.1371/journal.pone.0052453

Abstract

The saber-toothed cat, Smilodon fatalis, and American lion, Panthera atrox, were among the largest terrestrial carnivores that lived during the Pleistocene, going extinct along with other megafauna ∼12,000 years ago. Previous work suggests that times were difficult at La Brea (California) during the late Pleistocene, as nearly all carnivores have greater incidences of tooth breakage (used to infer greater carcass utilization) compared to today. As Dental Microwear Texture Analysis (DMTA) can differentiate between levels of bone consumption in extant carnivores, we use DMTA to clarify the dietary niches of extinct carnivorans from La Brea. Specifically, we test the hypothesis that times were tough at La Brea with carnivorous taxa utilizing more of the carcasses. Our results show no evidence of bone crushing by P. atrox, with DMTA attributes most similar to the extant cheetah, Acinonyx jubatus, which actively avoids bone. In contrast, S. fatalis has DMTA attributes most similar to the African lion Panthera leo, implying that S. fatalis did not avoid bone to the extent previously suggested by SEM microwear data. DMTA characters most indicative of bone consumption (i.e., complexity and textural fill volume) suggest that carcass utilization by the extinct carnivorans was not necessarily more complete during the Pleistocene at La Brea; thus, times may not have been “tougher” than the present. Additionally, minor to no significant differences in DMTA attributes from older (∼30–35 Ka) to younger (∼11.5 Ka) deposits offer little evidence that declining prey resources were a primary cause of extinction for these large cats.

Highlights

The saber-toothed cat, Smilodon fatalis and American lion, Panthera atrox were among the largest of the Pleistocene terrestrial carnivores; these, along with other megfauna were extinct by,12,000 years ago [1]
This idea is inconsistent with interpretations of high incidences of tooth breakage in extinct Pleistocene carnivorans from La Brea compared with extant taxa
We suggest that tooth breakage data may be recording damage from both carcass utilization and preycapture, with greater tooth breakage occurring due to increased prey size

Summary

Introduction

The saber-toothed cat, Smilodon fatalis and American lion, Panthera atrox were among the largest of the Pleistocene terrestrial carnivores; these, along with other megfauna were extinct by ,12,000 years ago [1]. We hypothesize that if prey became scarcer (either due to humans entering the carnivore guild or climate change, or both), competition might have forced large-bodied cats to consume both soft/tough tissues and less-preferred, harder bone. P. atrox has the greatest incidence of tooth breakage of canines (36%) while S. fatalis has the lowest incidence for extinct Pleistocene taxa (11.2%) [11] These data contrast with those for extant large carnivorans, which have average canine breakage of ,7%, including felid values averaging between 3.2% to 9.8% (in the jaguar, Panthera onca and leopard, Panthera pardus, respectively) and hyaenid values averaging between 8.3 to 9.6% (in the striped hyena, Hyaena hyaena and spotted hyena, Crocuta crocuta, respectively) [11]. While Van Valkenburgh and Hertel [10] exclude this explanation because both prey and predator sizes are larger during the Pleistocene, it is important to note that larger predators have relatively weaker teeth for a given tooth shape (e.g., canines can support a smaller percentage of an animal’s body weight with increased body size) [13,14,15]

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Conclusion