The fossil record offers unique insights into evolutionary patterns that cannot be inferred from living species alone. Fossils provide a critical temporal element to macroevolutionary studies, allowing us to strengthen phylogenetic inferences, document morphological change through time, and directly calibrate divergence events. My past research lies at the intersection of phylogeny, phenotype, and time, relying extensively on fossil specimens to detect patterns of morphological change over deep time. In one study, using tetraodontiform fishes (pufferfishes and relatives) as a model system, I combined phylogenomic data, paleoclimatic records, and body size measurements from living and fossil species to test long-standing macroevolutionary hypotheses of body size evolution. These analyses revealed that increasing body size correlates with cooling ocean temperatures through time, providing strong support for both Bergmann’s and Cope’s rules in marine fishes. In another study, I used 3D morphological data from exceptionally preserved fossil jaws of early bony fishes (423–359 Ma) to uncover an adaptive radiation that was driven primarily by lungfishes and coelacanths, standing in contrast to their “living fossil” descendants of today. Together, these studies highlight how fossils capture often unseen evolutionary dynamics and underscore the importance of paleontological data for understanding evolutionary diversification.