Origin of the wildlife of Brazil
The cause of Brazil’s unique wildlife is found in prehistoric times. The rock plates of the continents slowly move over the earth’s surface, a process that is known as ‘Continental Drift’. A look on the world map reveals that South America and Africa seem to fit together. About 200 million years ago, South America and Africa were indeed joined together forming one gigantic supercontinent called Pangaea. During the Cretaceous period, the rock plates that the continents sit on began to move apart. South America became separated from Africa and was connected with Antarctica and Australia.
After a few million years, evolution took its course and the animal species from South America, Antarctica and Australia began to differ from those in Europe, Africa, North America and Asia. The most striking example of this difference is the occurrence of marsupials in both South America and Australia while there are no marsupials in Europe or Africa. Antarctica continued to move southwards and was covered under a thick layer of ice, killing most life on Antarctica.
Around 3 million years ago, a land bridge was formed between North America and South America. During the resulting Great American Interchange, many land and freshwater species migrated from North America via Central America to South America and vice versa. Many marsupials and other South American mammals became extinct as they could not compete with the mammals from North America. Other species managed to survive and some species like the opossum and the armadillo even managed to settle in North America.
South America still has many families of plants and animals that are typically South American. Typical South American species are the sloths, the armadillos and the humming birds. The monkeys of the New World belong to other families as the monkeys of Africa and Asia. While rodents occur all over the world, the Cavy family occurs only in South America and includes the guinea pig and the Capybara.
Ice Ages
Scientists believe that the last ice age also played an important role in the development of South-America's tremendous biodiversity. An ice age is a period of long-term reduction in the temperature of Earth's climate. The last ice age took place between 18,000 and 14,000 years ago. While Europe and Northern America where covered with ice, large parts of South-America was covered with Cerrado and Caatinga vegetation.
The rainforest and its gigantic trees could only survive in small, humid areas. These areas are known as sanctuaries or refugias. As these areas were separated, the evolution of plant and animal species was separated as well. When the Earth warmed up again, the rainforests expanded and the species of the different sanctuaries ended up finding each other. It is believed that the richness of the Amazon rainforest is a consequences of that mixture.
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