Era
Tertiary
26
Cenozoic
25
Miocene
24
Pliocene
10
Mesozoic
7
Pleistocene
7
Cretaceous
6
Quaternary
6
Neogene
5
Paleozoic
5
Permian
5
Eocene
4
Oligocene
3
1838-1914
2
Holocene
2
Jurassic
2
Mississippian
2
Ordovician
2
Pennsylvanian
2
Precambrian
2
Triassic
2
1898-1974
1
1938-
1
Cambrian
1
Carboniferous
1
Devonian
1
Paleocene
1
Paleogene
1