Heterodonty, having multiple different types of teeth in the jaws, is well documented in chondrichthyan and sarcopterygian lineages, but is poorly documented within the Actinopterygii (ray-finned fishes). To further our understanding of actinopterygian dentition, a broad-scale literature review of tooth types across all families of actinopterygian fishes was conducted to (1) summarize the diversity of oral jaw teeth that exists within the group and (2) assess the distribution of heterodonty. Based on a thorough survey of the published literature on actinopterygian fishes, 15 distinct types of oral jaw teeth are recognized and named based on attributes of tooth shape. Heterodonty is widespread within the Actinopterygii and is documented in 20 of the 45 orders ray-finned fishes. The oral jaws of actinopterygiian fishes have 39 distinct forms of heterodonty, which comprise two, three or four different tooth types. The results of ancestral character state reconstruction analyses, conducted in conjunction with a recently published molecular phylogenetic hypothesis for actinopterygian fishes, confirm that heterodonty has evolved multiple times throughout the evolutionary history of the group and suggest that a homodont dentition comprised only of coniform teeth is a plesiomorphic condition for the Actinopterygii. Summaries of oral jaw teeth are provided for 3,000 species of ray-finned fishes, representing 442 families and 45 orders.
