<p>The Ross Sea basins, shaped by Late Cretaceous and Cenozoic extension within the crust of the Ross Sea, represent key regions for understanding continental rifting processes. However, the dynamic mechanisms driving the transition from diffuse extension to focused extension in these basins remain poorly understood. Here, we provide a comprehensive model of crustal extension in the Ross Sea basins, detailing the kinematic and dynamic evolution from 100 Ma to the present on the basis of published finite rotation poles. Our model illuminates the complex relative motions between the West Antarctic and East Antarctic Plates and quantifies the crustal strain rates associated with their relative movements. We show that West Antarctica began to move away slowly from the East Antarctic and rotated clockwise at approximately 53 Ma, and the motion progressively decreased until it ceased at approximately 11 Ma. This kinematic shift temporally coincided with the onset of focused rifting, indicating a transition from broadly distributed extension in the eastern Ross Sea to localized deformation in the western basin. Time-resolved strain rate fields further reveal several hundred kilometers of total crustal extension, suggesting a primary influence of evolving plate motions over passive lithospheric weakening. These findings refine the tectonic history of the Ross Sea and provide a reproducible framework linking rift basin evolution to global plate motion.</p>