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The Four Major Eras

In total the Earth was divided into 4 important Eras each bringing evolution to their own. Today they are known as the Precambrian Era, Paleozoic Era, Mesozoic Era & Cenozoic Era. Each occurring billions of years ago along with the age of our Earth (4.6 billion years old.) scientist have discovered billions of years old radioactive uranium.

Precambrian Era

In this era there were 3 main periods well known as the Hadean, Archean & Proterozoic Periods. The Hadean period took place about 4,600 million years ago which at that time was the formation of the solar system.The earth's crust at last cool down enough for the continental plates to shape in the Archean period which was about 4,000 million years ago. Finally 2,500 million years ago the Proterozoic period took place whre Earth's shape was beginning to look as it is now.

Precambrian Era Major Events

During this era and periods within, organisms developed the ability to photosynthesize. In other words grow and evolve. But also oxygen is produced and causes life to be able to be supported. Simple unicellular prokaryotes, sponges, and jellyfish are some organisms that lived at the time, but are still here today. The world was complex like a puzzle.

Paleozoic Era

In this era there are numerous period within such as the Cambrian , Ordovician , Silurian, Devonian, Carboniferous, & Permian periods. But 541 million years ago the Cambrian period took place;known as the stage of Ancient life, 485 million years ago the Ordovician period occurred which was part of the Cambrian extinction, The Silurian period transpired 444 million years ago; at the same time time sea levels were ascending. In addition the Devonian period took place 419 million years ago. Also known as the Missisipian & Pennsylvanian period; the Carboniferous prevailed 358 million years ago. Finally 298 million years ago the permian period transpired.

Paleozoic Era- Major Events

Within this era what defined this was the diversification of fossil records which showed many different types of animals and plants. Also developation of invertebrates and vertebrates during this era defined it as well. Some organisms include worms, sea stars, arthropods, and amphibians. But most importantly the Cambrian explosion occurred during this era. Which was also the worlds largest mass extinction of known to record. Therefore 90% of marine life and 70% of land life went extinct. Concluding the Paleozoic Era with the Permian Extiction.

Mesozoic Era

Throughout this era there were three focal periods. About 251 million years ago the Triassic period took place. Also at this time Birds made their first appearances. Which was the first period out of the three during this era. In continuation the Jurassic period ensued 200 million years ago which was the middle of the Mosozoic Era. In addition was he time to the largest animals, Dinosaurs. But ending this era was the Cretaceous period dating back to 145 million years ago. This was the period with the loss of all dinosaurs except birds

Mesozoic Era- Major Events

This much larger and complex era brought intricate mammals, birds, and Dinosaurs. This "Middle Life" Era was diversified by huge reptiles, atrocious beast, and dinosaurs for only 186 million years ago where they roamed the Earth, but soon after the age of the dinosaurs soon came to an end by the collision of an asteroid. At this point dinosaurs have gone extinct 65 million years ago. As the separation of the continents altered an important part in shaping our world today. Bringing an end to the Mesozoic Era.