ERA
|
PERIOD
|
CHARACTERISTICS
|
BEGAN ___ MILLION YEARS AGO
|
| 0 |
Cenozoic
|
Quaternary
|
Ice Age, modern humans appear
|
2 |
Tertiary
|
Abundant Mammals
|
66 |
Mesozoic
|
Cretaceous
|
First flowering plants; Mass extinction of Dinosaurs, ammonites, and
others
|
144 |
Jurassic
|
First primitive birds; abundant dinosaurs
|
208 |
Triassic
|
First dinosaurs & small mammals, first conifer forests
|
257 |
Paleozoic
|
Permian
|
Mass extinction of trilobites & other marine animals
|
297 |
Carboniferous
|
Pennsylvanian: Fern forests, first reptiles
Mississippian: Large primitive trees
|
323 |
Devonian
|
First amphibians; fish diversity
|
360 |
Silurian
|
Early land plants; marine reefs
|
415 |
Ordovician
|
Jawless armored fish
|
438 |
Cambrian
|
First abundant complex marine life forms eg trilobites, Burgess Shale
animals
|
490 |
Precambrian
|
Proterozoic
|
One celled organisms, bacteria, protistas
|
543 |
|
Archean
|
Oldest primitive fossils, bacteria
|
2500 |
Origin of the Earth: Coalescence of planetary debris
|
4600 |