Characteristics: ​New complex lifeforms developed in huge numbers in the oceans and evolved eyes, jaws, and the ability to crawl onto land from shallow water. Plants begin to appear on land millions of years before any animals would make the journey. This Eon would showcase some of the earliest and simplest animal lifeforms, and ultimately include the ancestors to all living things today. The dinosaurs would evolve more than halfway through this Eon, and die out 66 million years ago. This was followed by an ecological explosion of small mammals and after more than 60 million years more, humans would finally appear. Multiple mass extinctions took place, ex. Permian, and Cretaceous.

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Three major eras occurred during the Phanerozoic: 1. Paleozoic. 2. Mesozoic. 3. Cenozoic.

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The Phanerozoic is characterized by a huge increase of diverse lifeforms both in the oceans and on land. Fossilized evidence points to a major radiation of species and complexity of those organisms during the Cambrian Period, the first period of the Paleozoic. This proliferation of lifeforms is known as the Cambrian Radiation, or Cambrian Explosion.

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Increasing oxygen levels is viewed by some as being a major contributor to the boom of life both in water and on land. "An oxygen-rich atmosphere can release phosphorus and iron from rock, by weathering, and these elements then become available for sustenance of new species whose metabolisms require these elements as oxides." Oxidization had been occurring for billions of years (possibly as far back as the Archean) through the process of photosynthesis, but had never reached levels above 1 or 2 percent of atmospheric composition. What changed was

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​Biology -

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All modern forms of life grew out of this time period. Mammals, reptiles, crustaceans, arthropods, insects, fish, everything evolved from animals that first appeared in the early Cambrian. Millipedes were some of if not the first animals to walk on the planet, and would be followed by creatures similar to lung fish, learning to breath above water and find newer safer dwellings from the increasing dangerous and predation of the water. Early formations of plant life would begin during this age as well, and over the course of millions of years, the first forests would appear on land, forever changing it's surface and the atmosphere with huge contributions to Earth's oxygen levels. Die offs would occur in mass throughout this Eon, but each one brought the evolution of greater, more complex and diverse species of life all the way to the present day.

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A series of mass extinctions would occur throughout this Eon, non more famous than the KT Extinction event that brought an end to most dinosaurs 66 million years ago. This was mass die off was triggered by a meteorite the size of Mount Everest, colliding with the earth at more than 40,000 miles per hour off the Yucatan Peninsula in present day Mexico. The meteorite was unlike anything the world has likely seen since and was long enough that it were placed on the ground, the top of it would be above most high altitude airplanes today. Such a colossal collision was responsible for a complete power shift, ending the age of Reptiles and creating all new ecological niches for mammals, the likes of which would enable a specialized arboreal (tree dwelling) group, known as primates, to evolve. These early primates over tens of millions of years would become apes, some of which took to the ground, and eventually evolved into modern humans roughly 250,000 years ago. Linguistic ability in humans did not come along until perhaps 50,000 years ago. Our earliest ape ancestors likely appeared close to 5 or 7 million years ago.

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Geology -

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The earth would undergo it's most transformative geological period in the Phanerozoic as great continents split apart, and with agonizingly slow speeds crashed into one another. Supercontinents like Pangea formed where every continent was merged into one, and over hundreds of millions of years, they would separate until today's arrangement was reached. These changes would have huge contributing factors to the present climate of these ages, as in the Permian and Triassic when Pangea kept ocean air from penetrating the inland, creating a scorching desert for hundreds of miles, or the gradual breakup through the Cretaceous enabling lush landscapes and tropical habitats to form in the cooler, humid spread of separate continents.

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