The Paleozoic Era has 6 different periods. The Permian, Carboniferous, Devonian, Silurian, Ordovician, and Cambrian.

The Cambrian Period was the first of 6 periods during the Paleozoic era. This period lasted for nearly 53 million years. The climate was cold at first but over time it warmed up. There were only animals without backbone called invertebrates. As far as plants are concerned there were mostly single-celled algae. At the end of the Cambrian period there was a mass extinction.

Second period in the Paleozoic era. During the first part of the period the climate was warm but as the continents stopped moving glaciers formed falling in the ocean, cooling down the temp. quite a bit. Life was still primarily found underwater, but there were more different species than ever before. Moss evolved along the shore line.

Third period of the Paleozoic era. Much warmer climate. The warmer climate caused the glaciers to melt and the seas to rise. Marine life continued to grow. Coral reefs began to evolve during this time. Also mosses and other plants began to grow. There are signs that there were insects living in the moss and other plants.

Fourth period of the Paleozoic era. During this period the land mass changed. During this period the climate was warm. During this time marine animals developed with jaws, gills, and paired fins. The coral reefs are still developing and more types of plants formed on land.

Lasted about 64 million years. The shifting continents of this time created the mountains. These mountains had no plant life. As the land grew many diverse land animals evolved such as reptiles. More insects were created in this period and the climate was warm but with the glaciers falling into the oceans the climate temp. went down along with the number of sea animals.

Final period of the Paleozoic. Climate was very dry. Animals and plants had to adapt to this new climate. The reptiles really liked the dry climate. Coral reefs start to build again. The Permian period ended with a mass extinction. No one is really sure how the extinction occurred.