| | | | | |
| Era | Period | Epoch | Million Years Ago | | Characteristic Life |
|
| |
| Paleozoic | Permian | | 286 | | Rise of primitive reptiles. Extinction of the trilobites. Climate was cold at the beginning but warmed progressively. Widespread extinctions at the end of this period. |
| | | | | | |
| | Pennsylvanian | | 330 | | Earliest know insects, large arthropods. Climate generally warm and humid. Extensive coal producing swamps. Many specialized amphibians and the first appearance of reptiles |
| | | | | | |
| | Mississippian | | 360 | | Extinction of some fish lineages and expansion of others. Beginning of large coal production swamps. Extensive radiation of amphibians. |
| | | | | | |
| | Devonian | | 408 | | Explosion of fish and disappearance of many jawless varieties. First winged insects and tetrapods. Land was higher climate cooler. |
| | | | | | |
| | Silurian | | 438 | | Earliest know land animals . Primitive plants. Rise of fishes. Abundant trilobites. |
| | | | | | |
| | Ordovician | | 505 | | Earliest know vertebrates. Primitive plants. Trilobites and cephalopods abundant. |
| | | | | | |
| | Cambrian | | 550 - 590 | | Extensive shallow seas. Brachiopods and trilobites common. |
| | | | | | |
| Precambrian | Proterozoic | | 2,500 | | Primitive water dwelling plants and animals. Changes in the lithosphere produced major land masses and shallow seas. |
| | | | | | |
| | Archean | | 4,600 | | Oldest know life (mostly indirect evidence). Formation of the earth and slow development of the lithosphere, hydrosphere and atmosphere. Development of life in the hydrosphere. |