Clustering crocodylian dental morphology: Insights into functional adaptations, diet, and ontogeny

Crocodylians have often been grouped into ecomorphological categories based on snout characters and diet, but quantitative dental morphology has rarely been used for this purpose. We collected Euclidean measurements from the teeth of 18 extant crocodylian species spanning a range of sizes and snout ecomorphotypes, normalized the data for size heterodonty using regression analyses, grouped the crowns into eight dental sections along the arcade, and ran a K-means cluster analysis to cluster individuals based on shape heterodonty. Five clusters emerged, each reflecting different degrees of gracility or robustness of crowns and their variation along the jaw arcade. These morphological clusters showed a connection to snout shape, prey preference, and feeding ecology, particularly prey size and the degree of processing necessary. Cluster assignments were, for the most part, not taxon specific; multiple families and subfamilies were found in most clusters, and members of the same species were often found in more than one cluster. For species with members in multiple clusters, the larger individuals typically were in the cluster with more robust crowns. This supports prior suggestions that dental morphotype coincides with ontogenetic niche shifts. This approach demonstrates the potential for using dental morphology to infer ecological roles in both extant and fossil crocodylians, paving the way for future comparative analyses of archosaur dentition.