Morphological convergence obscures functional diversity in sabre-toothed carnivores

Abstract

The acquisition of elongated, sabre-like canines in multiple vertebrate cladesduring the last 265 Myr represents a remarkable example for convergentevolution. Due to striking superficial similarities in the cranial skeleton,the same or similar skull and jaw functions have been inferred for sabre-toothed species and interpreted as an adaptation to subdue large-bodiedprey. However, although some sabre-tooth lineages have been classifiedinto different ecomorphs (dirk-tooths and scimitar-tooths) the functionaldiversity within and between groups and the evolutionary paths leadingto these specializations are unknown. Here, we use a suite of biomechanicalsimulations to analyse key functional parameters (mandibular gape angle,bending strength, bite force) to compare the functional performance ofdifferent groups and to quantify evolutionary rates across sabre-tooth ver-tebrates. Our results demonstrate a remarkably high functional diversitybetween sabre-tooth lineages and that different cranial function and preykilling strategies evolved within clades. Moreover, different biomechanicaladaptations in coexisting sabre-tooth species further suggest that thisfunctional diversity was at least partially driven by niche partitioning