Approximately ________ mya, all landmasses on Earth formed a single supercontinent called ______. As this supercontinent began t
o break up _____ mya, the modern continents we know today began to drift apart. Whales began to evolve_______ mya when these continents were well separated. Fossils of early whale relatives that only swam in freshwater are found near ______. Fossils of fully _____whale relatives are found _____.
