Earth has a lengthy and intricate history. The changes that occur are two slow for people to be conscious about. Awareness of the theory of evolution is quite fresh, yet we have made a lot of progress. We will start our journey through the Earth's evolutionary timeline from nearly 5 billion years ago. Earth and nine additional planets revolve around the sun. Our researchers have reasons to believe that all the planets in our solar system …showed first 75 words of 613 total…

…showed last 75 words of 613 total…called the Cenozoic era. Mammals become more dominant than reptiles. Marine life takes on a modern look. Large mammal extinction takes place. The mastodon and mammoth, which are close relatives of the elephant, become extinct. Scientists can't come up with a reasonable explanation for these massive extinctions. One hypothesis is that early humans started hunting large forms of a certain type of mammal and exterminated them all. This theory though, is not accepted by everybody.