Jurassic-Cretaceous (J-K) ammonoids experienced remarkably rapid rates of evolution and extinction. The processes that fueled this evolutionary volatility are not well understood. Evolutionary relationships among and within the six J-K ammonoid suborders are incompletely reconstructed, in part because the homeomorphy and intraspecific variability complicates phylogenetic analysis. J-K ammonoids appear to have been developmentally flexible; heterochronic shifts in their evolution are common and taxa are often distinguishable by variations in the timing of developmental events. Changes in environmental variables are consistently correlated with both diversification and extinction in J-K ammonoids. The tectonic separation of Pangea, greenhouse warming, and sea level change drove ammonoid dispersal and the development of biogeographic provinces. A synthetic view of J-K ammonoid evolution provides the foundation for a model of ammonoid speciation in which sea level change provides new epeiric sea microhabitats into which ammonoids disperse while developmental flexibility provides the morphological and ecological variation to fuel divergence and speciation. New quantitative and geospatial approaches will allow us to integrate phylogenetic and paleobiogeographic data to better understand the macroevolution of these cephalopods.