If the earth was experiencing an extremely high gravitational field -- extremely high by today's standard -- then it is possible the continents did not simply "drift apart." The Ball-of-Light Particle Model predicts they "spread out" as the size of the earth swelled.
Graphic of two globes different size, where continents spread
As the orbit of the earth has changed through history, it has created greater and lessor forces on the crust of the earth. I believe this has created a very long-term pulsating in the size of the earth's crust. Below is an animation I created to demonstrate concepts for a pulsating star. This animation could also be used to visualize the pulsating of the earth's crust over a very long time period.
Personally, I believe that the solar activity has been dominate in changing the ocean level over medium level time periods of hundreds and thousands of years, but the changing orbit and gravitational field has had the dominate role on ocean levels over hundreds of thousands and millions of years.
(See also, Lowering of Gravity Swells Earth's Volume)
(See also, Planet Formation)
(See also, Cone Nebula)
(See also, Changing Planetary Orbits)
(See also, external link to Ocean Level Changes on the Heliometeorolgy page.)