The Earth we live on now is drastically different from how it was millions of years ago. The Earth has gone through many changes and events though time. There are five major events in history that have changed the world. Without these five mass extinctions who knows what Earth would have looked like, and if humans would even be alive.
In the ordovician period 439 million years ago there was a mass extinction that wiped out 89% of life on Earth. There was two major events that occured; glaciation and falling sea levels. In the ordovician period scientists believe that the whole planet was so over populated with plants that they removed too much carbon dioxide from the air, which drastically reduced the air temperature. The earth was mostly covered with water making the majority of animal life in the ocean. The mass extinction caused trilobites, agnostida, and ptychopariida to completely die out, but it harmed many other animal and plant life. …show more content…
It is unclear if this happened in one single major event or spread over hundreds of thousands of years. The cause of all the animal extinction is thought to be from the huge land plant life. Giant land plants released nutrients into the oceans. The nutrients in the water lead to mass algal blooms which decreased the seas oxygen and animal life. The cold temperature, due to the volcanic as, killed off the spider and scorpion type animals. Elpistostegalians also died off, many sea animals went extinct during this time