Incisor size and shape: Implications for feeding behaviors in saber-toothed ''cats''

Although the great size and procumbency of the incisor teeth of many saber-toothed carnivorans have long been recognized, the potential functional significance of carnivoran incisor size and shape remains largely unexplored. Here, we explore upper incisor design and incisor arcade shape in living felids, canids, and hyaenids. In addition, we compare upper incisors of saber-toothed carnivorans with those of modern carnivorans and use these data to infer aspects of saber-tooth killing and feeding behaviors. Results demonstrate that the shape of individual upper incisors of extant carnivorans is intricately related to the dental arcade in which the teeth are rooted. Canids and hyaenids have robust incisors in parabolic arcades, whereas felid incisors are weaker, particularly in mediolateral bending, and are located in transversely linear arcades. It is proposed that the strength of the medial incisors is in part a consequence of arcade shape. Incisors in linear arcades can be weaker because they are better buttressed by adjacent incisors than is the case for incisors in curved arcades. Incisor strength in anteroposterior bending is better explained by differences in killing and feeding behavior. Arcade procumbency and incisor robusticity also appear to be common features of the upper incisors of saber-toothed carnivorans, although these features are variably developed. The upper incisors of saber-toothed felids tend to equal or exceed those of living (conical-toothed) felids in strength and are located in moderately parabolic arcades. By contrast, nimravids have massively constructed incisors in arcades that are markedly curved comparable to those of canids. We hypothesize that saber-tooths may have relied on their incisors more intensively than do living felids for prey stabilization during killing bites and for the ingestion of flesh during feeding.