Variation in prey availability over time shaped the extinction dynamics of sabre-toothed cats.

Abstract

The role of ecological interactions and abiotic factors in shaping macroevolutionary patterns has been extensively debated. Yet, the effect of predator-prey interactions on diversification dynamics is unclear. Here, we test the influence of predator-prey interactions in the diversification of sabre-toothed cats, a subfamily of felids (Felidae: Machairodontinae) that developed a highly specialized morphology, the notoriously long upper canines. This morphology has been associated with a high degree of trophic dependence on large prey, which is assumed as one of the main reasons for the group's demise. To test the hypothesis that prey availability affected the diversification of sabretooths we examined whether shifts in speciation and extinction rates were linked with changes in the species richness of their potential prey clades. The only association we detected was between the increase in extinction rates of North American sabretooths and the decline in Equidae richness. However, when accounting for the prey richness per species, regardless of taxonomic affiliation of the prey, we found that the endpoint of most sabretooth taxa occurred when prey richness for that taxon was at its lowest. Our analyses then suggested that reduced prey richness was associated with increased extinction risk. These results support the hypothesis that the extinction of sabretooths was associated with the decline in megafauna, but extend it to more remote times, millions of years before their final demise, suggesting that prey availability contributed to drive the diversification dynamics of the group. More broadly, our findings highlight the importance of ecological interactions in shaping macroevolutionary patterns.