Seas are usually smaller and less deep than oceans. An ocean is a vast and a continuous frame of salty water that shelters almost 70 percent of the total earth's surface while a sea is a large body of saline water that occupies a greater part of the world's surface but is smaller than an ocean.
Since neither reptile could have swum great distances across salt water he inferred that they once lived on a single landmass that has since split apart.
