Relative Geologic Time |
GEOLOGIC TIME millions of years ago |
TIME OF APPEARANCE OF
DIFFERENT FORMS OF LIFE |
ERA |
PERIOD |
EPOCH |
C E N O Z O I C
|
Quaternary |
Holocene |
1.6 |
____ |
Pleistocene |
Ice age, human evolution |
Tertiary |
Pliocene |
5 |
Age of Mammals |
Miocene |
24 |
Spread of anthropoid apes |
Oligocene |
38 |
Origin of more modern families of mammals, grazing animals |
Eocene |
55 |
Origin of many modern families of mammals, giant mammals |
Paleocene |
66 |
Origin of most orders of mammals, early horses |
M E S O Z O I C |
Cretaceous |
Late Early |
138 |
Appearance of flowering plants; extinction of dinosaurs at end; appearance of a few modern orders and families of mammals |
Jurassic |
Late Middle Early |
205 |
Appearance of some modern genera of conifers; origin of mammals and birds; height of dinosaur evolution |
Triassic |
Late Middle Early |
240 |
Dominance of mammal-like reptiles |
P A L E O Z O I C |
Permian |
Late Early |
290 |
Appearance of modern insect orders |
Carboniferous |
Pennsylvanian |
Late Middle Early |
320 |
Dominance of amphibians and of primitive tropical forests which formed coal; earliest reptiles |
Mississippian |
Late Early |
360 |
Earliest amphibians |
Devonian |
Late Middle Early |
410 |
Earliest seed plants; rise of bony fishes |
Silurian |
Late Middle Early |
435 |
Earliest land plants |
Ordovician |
Late Middle Early |
500 |
Earliest known vertebrates |
Cambrian |
Late Middle Early |
570 |
Appearance of most invertebrate phyla |
P R E C A M B R I A N |
Proterozoic |
Late Neoproterozoic |
3,800 |
Origin of life; algae; worm burrows |
Middle Mesoproterozoic |
Early Paleoproterozoic |
Archean |