We describe an isolated lower jaw of a fossil bony fish collected from the Niobrara Chalk of western Kansas. The specimen exhibits some characters common to a relatively rare Late Cretaceous aulopiform fish genus Apateodus Woodward. However, because it also exhibits some features not found in Apateodus, along with its fragmentary condition and preservation mode, we conservatively refer it to as ‘cf. Apateodus sp.’ where it may belong to a previously undescribed aulopiform species phylogenetically allied to Apateodus. The recognition of this potential new taxon from the well-studied Niobrara Chalk demonstrates that there is yet to learn much about the biodiversity and paleoecology of the Western Interior Seaway that existed during the Late Cretaceous in North America.