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Precambrian Era
4600 mil. - 570 mil.		 Archaean Eon
4600 mil. - 2500 mil.		     From the formation of the Earth until the appearance of first abundant fossils.
Proterozoic Eon
2500 mil. - 570 mil.		    
Paleozoic Era
570 mil. - 245 mil.		 Lower Paleozoic Era Cambrian Period
570 mil. - 505 mil.		   Cambrian rocks contain the oldest fossils that can be used for dating. The whole animal kingdom developed. except for vertebrates.Plants included seeweads in the oceans and lichens on land. North America and Europe separated by water.
Ordovician Period
505 mil. - 438 mil.		   It was named for an ancient Welsh tribe, rocks of this age having first been studied systematically in Wales. The first vertebrates emerged. North America and Europe collided.
Silurian Period
438 mil. - 410 mil.		   Scorpion - the first air-breathing animal - developed.
Upper Paleozonic Era Devonian Period
410 mil. - 360 mil.		   Oceans covered much of what is now dry land, and fish were the dominant life form, including sharks and lungfish. The earliest known insect was found in Devonian rock.
Carboniferous Period
360 mil. - 286 mil.		 Mississippian (Lower) Period The predominant group of land animals was the Stegocephalia, lizardlike amphibians that developed from the lungfish.
Pennsylvanian (PeriodUpper) Evolution of the first reptiles. Other land animals included spiders, snails, scorpions, cockroaches, and the largest insect ever evolved, a species resembling the dragonfly, with a wingspread of about 74cm (29 in.).
Permian Period
286 mil. - 245 mil.		   Dissappearance of many forms of marine animals, rapid evolution of the reptiles.
Mesozoic Era
245 mil. - 66.4 mil.		 Triassic Period
245 mil. - 220 mil.		     The whole Mesozoic Era is also called the Age of Reptiles. The Triassic Period was the time of the evolution of the dinosaur (running on their hind feet). Other reptiles were ichtyosaurus and pterosaurus (flying reptiles). The first mammals appeared!
Jurassic Period
220 mil. - 144 mil.		     Wide range of dinosaurs continued to evolve - Brontosaurus (Apatosaurus), Tyrannosaurus, Stegosaurus. Primitive crocodyles appeared.
Cretaceous Period
144 mil. - 66.4 mil.		     First snakes, lizards,and crabs.
Cenozoic (Cainozoic) Era
66.4 mil. - present		 Tertiary Period
66.4 mil. - 1.6 mil.		 Paleogene Period
66.4 mil. - 57.8 mil.		 Paleocene Epoch Seven known mammal groups developed in northern Asia and migrated to other parts of the world.
Eocene Epoch Horse, camel, monkey, ... appeared. Also, ancestors of modern whales appeared.
Oligocene Epoch Most of the archaic mammals disappeared, new mammals appeared.
Neogene Period
57.8 mil. - 1.6 mil.		 Miocene Epoch The first appearance of grasses=> evolution of grazing animals (horses, camels).
Pliocene Epoch Climax of the Age of Mammals.

5 million years ago, our family tree sprouts in Africa. The earliest humans branch off from African apes. Humans, gorillas, and chimpanzees all share a common ape ancestor.
Quaternary Period
1.6 mil. - present		 Pleistocene Period
1.6 mil. - 10 thousand		   Buffalo, elephants, mammoths, etc. were abundant. First antelopes and lions appeared in Europe. First bears migrated to North America from Asia.

Homo sapiens, homo heidelbergensis, and homo neanderthalensis evolve, only homo sapiens survives.
Holocene (Recent) Period
10 thousand - present		   Animals and plants have not evolved much during this period. Fast ice melting caused the formation of substantial glacial lakes, including the Great Lakes.

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