The Precambrian times were not only the oldest …show more content…
It spans from 571 million years ago to the present day. The Phanerozoic eon is made up of 3 major eras, being the Paleozoic era, the Mesozoic era and the Cenozoic era. Another term used to describe this eon is "The creation of visible life." Although the first actual signs of life took place in the late Archeon eon of the Precambrian times, the major evolution, development and expansion of the living kingdom didn't kick start until the early to mid-Phanerozoic eon. This included the dinosaurs. The main reason for this sudden explosion of growth were the amounts of oxygen the simple plants were producing. The reason they were able to produce such high amounts of oxygen was due to the photosynthesis process the plants had learned as microscopic bacteria hundreds of millions of years before. While many new species of plants and animals were popping up everywhere, the Earth started creating new and different environments and biomes for these specimens to thrive and expand in. Some ways this happened was the Continental drift. The Continental drift occurred around 94 million years ago during the late Cretaceous period, and it was the global separating of the super continent Pangea. Other ways Earth was terraformed by were the formation of mountains and continental glaciation. (Young, 2016) The changes of the Earth's surface didn't affect the dinosaurs and their extinction. The dinosaurs went extinct due to an enormous …show more content…
In fact, it is one of the two other eras from the Phanerozoic eon, along with the Paleozoic and Mesozoic eras. The 3 ages that make up the Cenozoic era are the Paleogene, Neogene and Quaternary periods. During the Paleogene period, life was still and boring after suffering extreme damage from the recent asteroid collision. For around 10 million years, Earth was going through a cool, dry time. (Zimmermann, 2016) Once the planet was green and healthy again, small animals thrived without any predators. Non-dinosaur birds, for the first time, were at the top of the food chain. This didn't last for long though. Jungles were more abundant and were allowing the tiny animals to grow a little bit bigger with each generation. None of the mammals got to above 22 pounds, though. The middle of the Paleogene period was when the disruption of the Antarctic Circumpolar Current happened. This disruption spread another wave of coolness across the globe, receding jungles and allowing animals to grow larger and stronger. Some of them were even able to reach enormous sizes, such as whales. The late Paleogene period brought the return of grass. Grass allowed new species to evolve like elephants and dogs. The Neogene period was quiet and boring. Aside from early primates and the thriving of seed plants, there was the branching of animal species into new and undiscovered specimens. The