Variable Radius
One problem mass increase solves when applied to planets is the edges of the continents - they fit perfectly in a smaller earth. In the past, earth had less mass and a smaller radius.
This might have accounted for the enormous body plans of dinosaurs at the time - lower mass equals lower gravity.
Pangaea
Pangaea the ancient supercontinent assumes a fixed planetary radius in time and maps several continental edges well. But the remaining edges are lock-down fitted too, if we reduce the radius.
