| EON |
ERA |
PERIOD |
EPOCH |
TIME SPAN
(million years) |
AGE of |
| Phanerozoic |
Cenozoic |
Quaternary |
Holocene |
0-2 |
Mammals |
Humans |
| Pleistocene |
Mammals develop and become dominant
Extinction of dinosaurs (beginning of Paleocene) |
| Tertiary |
Neogene |
Pliocene |
2-5 |
| Miocene |
5-24 |
| Paleogene |
Oligocene |
24-37 |
| Eocene |
37-58 |
| Paleocene |
58-66 |
| Mesozoic |
Cretaceous |
66-144 |
Reptiles |
Flowering plants, height of dinosaurs |
| Jurassic |
144-208 |
1st birds/mammals, abundant dinosaurs |
| Triassic |
208-245 |
First Dinosaurs |
| Paleozoic |
Permian |
245-286 |
Amphibians |
End of trilobites & other marine animals
|
Carbon-
iferous |
Pennsylvanian |
286-320 |
Abundant insects, first reptiles |
| Mississippian |
320-360 |
Large primitive trees |
| Devonian |
360-408 |
Fishes |
First amphibians |
| Silurian |
408-438 |
First land plant fossils |
| Ordovician |
438-505 |
Marine Invertebrates |
First Fish |
| Cambrian |
505-570 |
1st shelled organisms,
trilobites dominant |
| Proterzoic |
Also known as Precambrian |
570-2,500 |
First Multicelled organisms |
| Archean |
2,500-3,800 |
First one-celled organisms |
| Hadean |
3,800-4,600 |
Approx age of oldest rocks (3800) |