Tectonic processes are often invoked to explain ecosystem changes, but their precise effects remain elusive. This study focuses on Jurassic-Cretaceous Northeastern Asia, linking the flourishing of the globally exceptional Yanliao and Jehol Biotas, which are temporally successive biotas with distinct species composition, to a prominent tectonic transition from crustal shortening to extension. We estimated paleo-elevation and paleo-temperature variations using whole-rock chemical parameters from Jurassic-Early Cretaceous continental arcs. Combined with published paleoclimate and paleontological records, our findings suggest that Mid-Late Jurassic plate convergence in Northeastern Asia created high elevations and complex topography with vertically zoned micro-environments, promoting the emergence of Yanliao Biota. In the Early Cretaceous, following recovery from a warm and arid climate interval across the Jurassic-Cretaceous transition, enhanced topographic ruggedness due to tectonic extension and local topographic/climate heterogeneity, diversified the Jehol Biota. This highly sculpted Northeastern Asia upland (2.0-4.5 km) hosted a wide spectrum of ecological niches under a relatively cool but heterogeneous climate, creating a key cradle for biodiversification.