When the Earth first formed and molten rock cooled to form masses of land within the oceans, the land mass was originally one piece. It was not separated into the individual continents that we have today.
This massive land mass, that still existed 220 million years ago when the first mammals evolved, was called Pangaea. No oceans divided the land and animals that lived on Pangaea could walk to one end to the other, if they had the time and ability.
After about 50 million years of mammalian evolution, the vast continent of Pangaea began to break up. Initially it split into two and then about 130 million years ago these two pieces both began to fragment. As the slabs of continental crust started to drift apart, floating on the molten rock beneath them, separate continents were formed. This movement was achingly slow ~ the movement of continents is still going on but the rate is slower than the rate of growth of a human fingernail.
This massive land mass, that still existed 220 million years ago when the first mammals evolved, was called Pangaea. No oceans divided the land and animals that lived on Pangaea could walk to one end to the other, if they had the time and ability.
After about 50 million years of mammalian evolution, the vast continent of Pangaea began to break up. Initially it split into two and then about 130 million years ago these two pieces both began to fragment. As the slabs of continental crust started to drift apart, floating on the molten rock beneath them, separate continents were formed. This movement was achingly slow ~ the movement of continents is still going on but the rate is slower than the rate of growth of a human fingernail.