Paleontology provides information about the history of morphological transformations, whereas developmental biology provides information about how such transformations happen at a mechanistic level. As such, developmental evidence enriches paleontology in formulating and assessing hypotheses of homology, character definition, and character independence, as well as providing insights into patterns of heterochrony, evolvability of features, and explanations for differential rates of evolution. The focus of this article is to review a series of case studies that illustrate how our understanding of paleontology is enriched by data generated by developmental biologists. The integration of paleontological and developmental data leads to a greater understanding of evolution than either of these sciences could have reached alone. Our case studies range from fish to mammals and involve somite and vertebral formation, limb loss, hand and foot patterning, and tooth formation.