Era
Precambrian
10
Mesozoic
8
Tertiary
5
Permian
4
Proterozoic
4
Quaternary
4
Carboniferous
3
Cretaceous
3
Paleozoic
3
Cambrian
2
Cenozoic
2
Devonian
2
Miocene
2
Pleistocene
2
1848-1929
1
1860-1939
1
1864-1953
1
1890-1980
1
1938-
1
1947-
1
1960-1988
1
1965-1980
1
1975-1994
1
21st century
1
Archaean
1
Holocene
1
Oligocene
1
Ordovician
1
Triassic
1