Implications of Diet for the Extinction of Saber-Toothed Cats and American Lions

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.

Cougars’ key to survival through the Late Pleistocene extinction: insights from dental microwear texture analysis

“…We used Dunn's procedure to conduct multiple comparisons (either between taxa or between like taxa across time) absent of the Bonferroni correction (see [12] for a discussion regarding the exclusion of the Bonferroni correction), and Mann-Whitney tests to compare between two taxa or the same species through time. Levene's test (medians), also known as the Brown-Forsythe test, was used to compare variance been extinct and extant taxa.…”

“…the sabre-toothed cat, Smilodon fatalis [9,10], and the dire wolf, Canis dirus [9]). While less information is available on the dietary ecology of Pleistocene cougars, dental microwear texture analysis (DMTA) can elucidate the textural properties of consumed food, including durophagy in extinct and extant carnivorans [11,12].…”

The phylogenetic signal in tooth wear: What does it mean?

“…In many cases, the diets of extinct taxa are also vastly different from those of extant taxa, despite being members of the same family (e.g. Kaiser, 2011, Mihlbachler, Rivals, Solounias, & Semprebon, 2011; DeSantis, Schubert, Scott, & Ungar, 2012). …”

Dental microwear texture as a proxy for diet in xenarthrans

“…Modern faunal specimens were examined in publicly accessible collections housed in the Australian Museum, Museum Victoria, and the Western Australian Museum (see Supplementary Table 13 for all specimen numbers and associated data). DMTA using white-light confocal profilometry and scale-sensitive fractal analysis (SSFA), was performed on all replicas of bilophodont teeth that preserved antemortem microwear, similar to prior work (Ungar et al 2003(Ungar et al , 2007Scott et al 2005;Prideaux et al 2009;Scott 2012;DeSantis et al 2012DeSantis et al , 2013Haupt et al 2013;Donohue et al 2013;DeSantis and Haupt 2014). Vombatids were not included in DMTA, because their tooth morphology is not analogous to the extant and extinct marsupials here examined.…”

“…All scans were analyzed using SSFA software (ToothFrax and SFrax, Surfract Corporation, www.surfrait.com) to characterize tooth surfaces according to the variables of complexity (Asfc) and anisotropy (epLsar). Complexity is the change in surface roughness with scale and is used to distinguish taxa that consume hard, brittle foods from those that eat softer/tougher ones (Ungar et al 2003(Ungar et al , 2007Scott et al 2005;Prideaux et al 2009;Scott 2012;DeSantis et al 2012DeSantis et al , 2013Haupt et al 2013;Donohue et al 2013;DeSantis and Haupt 2014;DeSantis 2016). Anisotropy is the degree to which surfaces show a preferred orientation, such as the dominance of parallel striations having more anisotropic surfaces-as is typical in grazers and consumers of tougher food items (Ungar et al 2003(Ungar et al , 2007Prideaux et al 2009;Scott 2012;DeSantis et al 2013;DeSantis 2016).…”