Two hundred million years ago, all of the continents on Earth were joined in one large supercontinent scientists call Pangaea. The formation of Pangaea dried up many shallow seas, which led to the evolution of new species on land. This is the time during which mammals first began to appear. During the Mesozoic Era, around 190 million years ago, Pangaea began to break up. The breakup resulted in two landmasses: Laurasia, the northern group of continents, and Gondwanaland, the southern group of continents. Gondwanaland included South America, Antarctica, Australia, Africa, and India. By the end of the Cretaceous Period 65 million years ago, Africa and South America had moved apart. By 43 million years ago, Australia and Antarctica had separated and moved to their present locations.
How do we know that these events actually happened? You have probably noticed that South America and Africa seem to fit together like puzzle pieces. Because of this fit, many people wondered if the continents once were joined. A German scientist named Alfred Wegener proposed that all of the continents once had been joined in a supercontinent that he called Pangaea. He suggested that Pangaea began to break apart millions of years ago, and that the continents continued to move until they reached their present locations. He called his hypothesis <span>continental drift. </span>Today, Wegener’s hypothesis is known as the theory of plate tectonics. Wegener was the first scientist to base his hypothesis on more than the fit of the continents. He collected data on rock formations, fossils, and climates to support his hypothesis. Wegener found the same rock formations and fossils in Africa, South America, and Antarctica. Some of the fossils were of species that grew in only one type of climate, yet the fossils were found on continents with differing climates. How could there be fossils of tropical and temperate climate species in Antarctica, a continent that is permanently covered with ice and snow? Have any fossils been found in Antarctica that can support Wegener’s hypothesis, and thus, the theory of plate tectonics?
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