Many fishes rapidly expand the oral cavity to draw prey into the mouth via suction feeding. Teleosts achieve suction using substantial cranial kinesis, including neurocranial elevation, suspensorial and opercular flaring, jaw and hyoid depression, and premaxillary protrusion. Polypterids share some of this mobility but lack protrusible jaws and a dual mechanism for mandibular depression, potentially reducing degrees of freedom in the feeding system. Despite this restricted mobility, Polypterus remain effective suction feeders, making them a useful system for understanding the basic components of suction feeding in actinopterygians. The goal of this study was to identify specific bone motions linked with suction feeding performance in Polypterus bichir. We predicted that ventral translation of the jaw and hyoid bar and lateral translation of the suspensorium would be highly correlated with prey velocity and acceleration. We quantified motions using XROMM and tested cross-correlations between prey velocity and dorso-ventral, medio-lateral, and antero-posterior translations of 5 skeletal elements (neurocranium, suspensorium, mandible, ceratohyal, and operculum) in 14 trials. Retraction and depression of the anterior ceratohyal and lateral flaring of the posterior ceratohyal are correlated with prey velocity (r > 0.69; p < 0.05, respectively); suspensorial flaring is not correlated with prey velocity. In these strikes P. bichir generated suction primarily through extreme motions of the ceratohyal, rather than through protrusion of the jaws or mobility of the palate. This suggests that while other kinesis mechanisms may enhance suction performance, ceratohyal mobility drives actinopterygian suction feeding. NSF DEB 1541547, MRI 1338036, SR01DE023831-04S1, MRI1626552.