Freak Felids - A Discussion of History's Largest Felines

[Ngala]

Evolutionary History of Saber-Toothed Cats Based on Ancient Mitogenomics Paijmans et al., 2017

*This image is copyright of its original author

Figure 1: Calibrated Phylogeny for Smilodon and Homotherium
Time-calibrated mitochondrial phylogeny of the Felidae, including the saber-toothed cat Smilodon and scimitar-toothed Homotherium. Node support is indicated by Bayesian posterior probabilities (see Figure S2 for RAxML phylogeny and bootstrap values). Calibrated nodes are indicated with a star (see also Table 2). Blue node bars indicate the 95% credibility interval of divergence times. The lower axis shows millions of years. Homotherium artwork was provided by Binia De Cahsan. The image of the mandible is adapted from [4]. See also Figures S1 and S2.

Highlights

• We present the first near-complete mitochondrial genomes from saber-toothed cats
• Smilodon and Homotherium are estimated to have diverged ca. 18 million years ago
• We find limited genetic divergence between American and European Homotherium
• Late Pleistocene Homotherium should be considered a single species: H. latidens
  

Summary
"Saber-toothed cats (Machairodontinae) are among the most widely recognized representatives of the now largely extinct Pleistocene megafauna. However, many aspects of their ecology, evolution, and extinction remain uncertain. Although ancient-DNA studies have led to huge advances in our knowledge of these aspects of many other megafauna species (e.g., mammoths and cave bears), relatively few ancient-DNA studies have focused on saber-toothed cats [1, 2, 3], and they have been restricted to short fragments of mitochondrial DNA. Here we investigate the evolutionary history of two lineages of saber-toothed cats (Smilodon and Homotherium) in relation to living carnivores and find that the Machairodontinae form a well-supported clade that is distinct from all living felids. We present partial mitochondrial genomes from one S. populator sample and three Homotherium sp. samples, including the only Late Pleistocene Homotherium sample from Eurasia [4]. We confirm the identification of the unique Late Pleistocene European fossil through ancient-DNA analyses, thus strengthening the evidence that Homotherium occurred in Europe over 200,000 years later than previously believed. This in turn forces a re-evaluation of its demography and extinction dynamics. Within the Machairodontinae, we find a deep divergence between Smilodon and Homotherium (∼18 million years) but limited diversity between the American and European Homotherium specimens. The genetic data support the hypothesis that all Late Pleistocene (or post-Villafrancian) Homotherium should be considered a single species, H. latidens, which was previously proposed based on morphological data [5, 6]." Reply