The genomes of most gnathostomes contain two paralogs of the gene, and , both of which are implicated in the development of two key morphological innovations: the jaw apparatus derived from the branchial arches and the paired appendages, whose evolutionary origins remain debated. Here, we investigate the expression patterns of and paralogs in the gray bamboo shark (), a representative of Chondrichthyes, a basally divergent gnathostome lineage. The paired fins of cartilaginous fishes are considered a basal model for gnathostome appendages. Our findings suggest spatial subfunctionalization of the and genes. Specifically, is expressed in the mandibular and branchial arches, as well as in paired and unpaired fins, indicating shared developmental mechanisms among these structures. In contrast, expression is predominantly restricted to paired fins, highlighting distinct developmental features that differentiate them from the evolutionarily older median fins.