Armed to the teeth: the underestimated diversity in tooth shape in snakes and its relationship to feeding constraints

Teeth are one of the most studied hard tissues in vertebrates. Their structure, composition and shape are related to dietary specialization in many species. At first glance, snake teeth all look similar; conical, sharp, curved. Yet, snakes, like other vertebrates, have very diverse diets that may have affected their shape. We compared the morphology of the teeth of 63 species that cover both the phylogenetic and dietary diversity of snakes. We predicted that prey properties play a role in shaping snakes teeth along with their feeding behavior. Limblessness combined to the peculiar feeding behavior of snakes impose strong functional constraints on their teeth, especially during arboreal or aquatic feeding. Our results show that prey hardness, foraging substrate and the main feeding constraint are drivers of tooth shape, size, and curvature. We highlight two main morphotypes: long, slender, curved with a thin layer of hard tissue for snakes that need a good grip on their prey and short, stout, less curved teeth in snakes that eat hard or long prey. Our study demonstrates the diversity of tooth morphology in snakes and the need to investigate the underlying functional implications to better understand the evolution of teeth in vertebrates.