The incredable shrinking planet?

In 400 BC the philosopher Plato estimated the circumference of the Earth to be 40,000 miles. In 250 BC Archimedes estimated it to be 30,000 miles. Today it is said to be 24,901 miles around. Has the Earth been getting smaller? If the mass has stayed about the same, but shrinking size has brought us closer to the center of mass, that would explain an increase in the pull of gravity over the eons. That is how dinosaurs 70 million years ago could have grown so large! The cooling of the Earth might have made it inclined to shrink. It makes a lot of sense.

Double-A