Columnaodus is an extinct genus of hybodontiform (shark-like cartilaginous fish) that lived during the Mississippian subperiod of the Carboniferous period. It was described in 2024 based on numerous isolated teeth recovered from a bonebed occurring in the contact zone of the Burlington and Keokuk Limestones on the border between Illinois and Iowa, USA.
The genus contains a single species, Columnaodus witzkei (Cicimurri et al., 2024). The teeth are characterized by a distinctive high, narrow crown morphology, suggesting a durophagous (shell-crushing) diet. It is hypothesized that Columnaodus may have fed on crinoids, brachiopods, and/or other shelled invertebrates.
The genus is classified within the order Hybodontiformes, a group of extinct shark-like cartilaginous fishes that were common from the late Devonian through the Cretaceous. Its familial placement within Hybodontiformes is currently considered uncertain (incertae familiae).
