Sharpening our understanding of saber-tooth biomechanics

Saber-teeth are a striking example of convergent evolution in vertebrate predators, having evolved multiple times in mammals and their early ancestors. While there is broad consensus that saber-toothed taxa employed a distinct biting strategy compared to conical-toothed carnivores, like the lion, the precise mechanics and variability of this bite remain debated. In this review, we integrate current knowledge of pointed tooth mechanics and puncture mechanics to explore predatory function, focusing on the canine shear-bite hypothesis. We quantify the key morphological characteristics of saber-teeth-elongation, slenderness, curvature, sharpness, and cross-sectional shape in a sample of saber-and conical-toothed taxa. Using the morphological diversity observed and insights from experimental studies, we examine the capacity of saber-teeth to perform the canine shear-bite, contrasting them with the clamp-and-hold bite of extant carnivores with conical canines. Our findings indicate that the morphological characteristics associated with extreme saber-tooth forms, as seen in Smilodon, suggest the prioritization of deeper puncture and slicing actions and limiting of lateral loads, favorable for a canine shear-bite. However, we also demonstrate that these morphological characteristics exist on a continuum accross saber-toothed taxa suggesting greater functional diversity beyond the shear-bite versus clamp-and-hold bite dichotomy. While this study refines our understanding of saber-tooth function, key gaps remain, particularly regarding the role of cross-sectional shape, curvature, and serrations in puncture mechanics.