Biochronology of the Planet Earth

4,600,000,000 years ago

Origin of the Earth and the solar system.

? 4,000,000,000 years ago

Origin of life, leading to production of oxygen.

? 1,500,000,000 years ago

First primitive soft-bodied animals; only a few fossils known; much evolution occurred, and the main types if invertebrates and some aquatic plants existed.

600,000,000 years ago

Many aquatic plants; some invaded the land; trilobytes; bracholopods, and many other invertebrates; shelly fossils begin to appear commonly.

500,000,000 years ago

Earliest known chordates; graptolites and corals widespread.

435,000,000 years ago

Club mosses and other primitive land plants abundant; some arthropods may have invaded land.

395,000,000 years ago

Fishes abundant; first amphibians; many land anthropods; horestails, ferns, and liverworts appear.

CARBONIFEROUS PERIOD - Huge forests of primitive plants

345,000,000 years ago - Mississippian Epoch - The Age of Amphibians

310,000,000 years ago - Pennsylvanian Epoch - Reptiles appear.

280,000,000 years ago

Extinction of many Paleozoic organisms such as trilobytes; amphibians decrease in importance.

230,000,000 years ago

Forests of conifers and cycads; first mammals; reptiles abundant and varied.

180,000,000 years ago

The Age of Ammonites; first birds.

135,000,000 years ago

Extinction of dinosaurs and many other mesozoic organisms; flowering plants appear.

TERTIARY PERIOD - Mammals abundant; firsty primates; flowering plants abundant.

67,000,000 years ago - Paleocene Epoch

58,000,000 years ago - Eocene Epoch

36,000,000 years ago - Oligocene Epoch

25,000,000 years ago - Miocene Epoch

7,000,000 years ago - Pliocene Epoch

2,000,000 years ago - Pleisocene Epoch

11,000 years ago - Holocene Epoch

reprinted from The Columbia History of the World, 1972, published by Harper & Row, edited by John A. Garraty & Peter Gay

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