The Paleozoic era was a time of many extinction events, culminating in the granddaddy of extinction events at the end of the Permian. Why were there were so many extinction events during this period?

Extinction events during the Paleozoic era were often caused by climate change (the advent of an ice age, for instance). The chemical composition of the environment also played a role in the survival of species. The mass extinction event at the end of the Permian Period may have been caused by volcanic eruptions, meteor strikes, sudden climate changes, or a combination of factors.

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The Paleozoic ("ancient life") era stretches out between about 541–252 million years ago. It was a time of great changes for the earth, and these changes often contributed to major extinction events, as species could not cope with the changes and died out.

For instance, in the Ordovician Period (485–444...

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The Paleozoic ("ancient life") era stretches out between about 541–252 million years ago. It was a time of great changes for the earth, and these changes often contributed to major extinction events, as species could not cope with the changes and died out.

For instance, in the Ordovician Period (485–444 million years ago), nearly eighty percent of sea species became extinct, for the climate shifted and an ice age started. The species in the shallow seas could not handle the cold, and sea levels dropped even further as glaciers formed, making it even more difficult for species to find water temperatures and depths necessary for survival.

The climate continued to shift as the eras passed. The earth became warmer, and glaciers melted, raising the sea level. The chemical composition of the environment, especially varying levels of carbon dioxide, also affected species. As always, species that failed to adapt failed to survive.

At the end of the Permian Period (299–252 million years ago), the world saw one of the most extensive extinction events ever as ninety-six percent of earth's species died out. No one knows exactly what happened, but evidence points to volcanic eruptions that drastically changed the earth's atmosphere, introducing gasses and dust that literally choked out living creatures. Such atmospheric disturbance would have limited the amount of sunlight, interfering with the process of photosynthesis and cooling temperatures. Other possibilities include meteor strikes, sudden climate shifts, methane discharge in the oceans, or all of the above in some combination. In any case, most species could not adapt to the changes, and they became extinct.

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