EON
|
ERA
|
PERIOD
|
EPOCH
|
TIME SPAN
(million years)
|
AGE of
|
Events
|
Phanerozoic
|
Cenozoic
|
Quaternary
|
Holocene
|
0-2
|
Mammals
|
Humans appear - Ice Ages - Mammals become
abundant - Alps and Himalayas form
|
Pleistocene
|
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 become abundant, diverse
and abundant dinosaurs - major extinctions mark end of Cretaceous
|
Jurassic
|
144-208
|
First birds, abundant dinosaurs
|
Triassic
|
208-245
|
First dinosaurs and mammals
|
Paleozoic
|
Permian
|
245-286
|
Amphibians
|
Abundant small reptiles appear - major
extinctions mark end of Permian
|
Carbon-
iferous
|
Pennsylvanian
|
286-320
|
Abundant insects, first reptiles -
Widespread coastal swamps
|
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
|
505-542
|
1st shelled organisms,
Abundant and diverse marine life appears
|
Proterozoic
|
Grouped as Precambrian
|
542-2,500
|
Primitive Life
|
First multicelled
organisms
|
Archean
|
2,500-3,800
|
First one-celled organisms - oldest
fossils
|
Pre-Geologic Time
|
3,800-4,600
|
No geologic record on Earth
|