Era
Mesozoic
18
Precambrian
17
Paleozoic
16
Tertiary
14
Cenozoic
9
Cretaceous
8
Pliocene
6
Triassic
6
Devonian
4
Jurassic
4
Permian
4
Mississippian
3
Pennsylvanian
3
Proterozoic
3
Quaternary
3
Cambrian
2
Carboniferous
2
Miocene
2
Pre-Quaternary
2
1834-1902
1
1946-
1
Archaean
1
Holocene
1
Oligocene
1
Ordovician
1
Pleistocene
1