The history of life on earth is divided into four major eras.
During the Precambrian era, which actually lasted for almost 90% of the whole time that life has existed on earth, the only forms of life were microscopic single-celled bacteria and eukaryotes, and some early multi-cellular life forms.
The Paleozoic era was life before the dinosaurs - invertebrates, early forms of fishes, amphibians, and early reptiles and mammal-like forms.
The Mesozoic era was the age of dinosaurs.
The Cenozoic era is the age of mammals that has emerged after the dinosaurs became extinct, and continues to the present time.
In the chart below, you see the geological time periods, how long ago they existed, the animals and plants that emerged during that time period, and on the right, major continents during that period of time.
During the Precambrian era, which actually lasted for almost 90% of the whole time that life has existed on earth, the only forms of life were microscopic single-celled bacteria and eukaryotes, and some early multi-cellular life forms.
The Paleozoic era was life before the dinosaurs - invertebrates, early forms of fishes, amphibians, and early reptiles and mammal-like forms.
The Mesozoic era was the age of dinosaurs.
The Cenozoic era is the age of mammals that has emerged after the dinosaurs became extinct, and continues to the present time.
In the chart below, you see the geological time periods, how long ago they existed, the animals and plants that emerged during that time period, and on the right, major continents during that period of time.
The stuff before the chart could use a lot more detail, but the chart was very helpful! Thanks!
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