The evolutionary history of feeding biology within fishes involves the diversification of skull mechanisms for suction feeding, biting mechanics, and food processing. Within reef-associated wrasses (family Labridae), the spectrum of feeding behaviors includes the extremes of suction and biting specialists. This diversity alongside a well-resolved phylogeny allows for rigorous phylogenetic comparative methods to be used to understand the evolutionary drivers of structural and functional changes in feeding. Using 3D geometric morphometrics, we investigated the planarity and shape of the three four-bar linkage systems within wrasses (oral jaws, opercular, and hyoid) across 155 species. We predicted that these three major 4-bar linkages would show different levels of variation and three-dimensionality, with the anterior jaws linkage hypothesized to be more planar, yet exhibit more variation, than the other linkages due to its pivotal role in prey capture. We found the oral jaws and the hyoid linkage to be more aligned in a 2D plane compared to the opercular linkage which extends more laterally. For the oral jaws linkage system, PC1 and PC2 mainly captured variation in the location of the coronoid process. PC1 and PC2 of the phylomorphospace for the opercular linkage system mainly captured the lateral position of the interopercle-opercle joint. The phylomorphospace for the hyoid linkage mainly captured the variation in location of the interhyal in relation to the post-temporal-neurocranial joint. We show that the three linkage systems vary in important geometric proportions effecting the transmission of force and motion during feeding. This study helps to understand the influence of these four-bar linkage systems on the overall cranial morphology of the skull within wrasses. NSF DEB-1541547