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Cambrian Period 570-500 MYA
During the Cambrian period, the earth was mostly covered in water, which had a lot of complex marine life while there was no life on land. -
Ordovician Period 488-443 MYA
The marine life was still flourishing underwater, but by this time the first plants began to live on land. The climate on land was mostly warm and wet, so there were tropics. The land massess came together making Gondwana and moved towards the south pole. -
Silurian Period 443-416 MYA
Reef systems began to flourish, fish were diversifying, animals began to evolve to walk on land. Bugs were beginning to live on land, being only a few cm long. Plants were actually rooting themselves on land. -
Devonian Period 316--358 MYA
Climate was warm and dry. Lycophytes, horsetails and ferns grew to large sizes and formed Earth’s first forests. The proliferation of plants increased the oxygen in the air, and CO2 depleted. Animals evolved to being breathing air and take advantage of the food-rich environment of the land. 3 extinction events killed great coral reefs, the jawless fishes and the trilobites, then Placoderms and most of the early ammonites. -
Carboniferous 359-299 MYA
Divided up into the Mississippian and thre Pennsylvanian periods. Climate was uniform, tropical, and humid. The continents were often flooded. They moved closer to form Pangea. The environmental conditions of the forests led to the formation of coal. -
Permian 299-251 MYA
Pangea was formed. The south was cold and barren, most of the land under ice. The north was wet and dry. Reptiles were the dominant land animals. At the end, it was the worst mass extinction in the planet's history. It wiped out 90% of marine life and 70% of land life by high carbon dioxide levels. -
Triassic 251-199 MYA
Pangea was still in place. It was very dry with very hot summers and cold winters. Ichthyosaurs dominated the oceans. Therapsids and archosaurs dominated. The earliest dinosaurs evolved during this time. The first mammals started to evolve at the end of the period. -
Jurassic 199-145 MYA
Pangea split apart. Global temperatures were getting warmer and diverse dinosaurs dominated the Earth. Ferns and gingkoes were the dominant plants on land. Gymnosperms were widespread. It was the age of the dinosaurs. Brachiosaurus were the plant eating dinos and the carnosaurs were the meat eating dinos. Early mammals were mostly herbivores and insectivores. -
Cretaceous 145-65 MYA
Pangea was definitely drifting more apart and started to form the present shapes of the continents today. Birds replaced the Pterosaurs in the air. Sauropods were being replaced by herbivorous Ornithischians and the T-Rex dominated. Large vertabrates and tropical invertebrates became extinct because of a meteor that hit Earth and alos volcanic eruptions. -
Tertiary 66-2.6 MYA
The beginning was warm and moist but later on in the period, temperatures started to cool and the first ice age began. The forests turned into grasses for the large grazing animals. Mammals became dominant. Hominids evolved as the human ancestors. Birds and fishes evolved into many diverse species. The insect population increased because of the plants that evolved nectar for them. The period ended with massive glaciers that covered the earth. -
Quaternary 2.6-present MYA
From the ice age, temperatures began to cool down. Grasslands supported the enormous herbivores that were preyed upon by large carnivores. As the temperatures cooled, forests grew and the larg herbivores and carnivores became extinct. The first humans evolved and fed off of the abundance of animal protein. They migrated from their origins to around the world and became known as the human race that it is today.
