The earliest Actinoptergyii (ray-finned fishes) and Sarcopterygii (lobe-finned fishes) have been studied intensely, and a consistent picture of interrelationships has begun to emerge for the latter. In contrast, there has been minimal documentation of the pattern of character acquisition leading to the osteichthyan crown. We review the synapomorphies proposed for various levels within osteichthyan phylogeny (total group; Acanthodes crown group; crown group; Sarcoptergyii; Actinopterygii), confirming some, rejecting others, and making new additions. This distribution of characters is used to interpret the placement of problematic Siluro-Devonian genera traditionally assigned to Actinopterygii, and suggests these taxa are stem osteichthyans. Earlier placements of these forms within the crown are symptomatic of taxonomies based on unpolarized similarities rather than synapomorphies.