Era
Tertiary
11
Precambrian
9
Cretaceous
8
Mesozoic
7
Miocene
6
Paleozoic
6
Permian
5
Cenozoic
4
Jurassic
4
Triassic
4
Archaean
2
Pennsylvanian
2
Quaternary
2
Silurian
2
1857-1920
1
1864-1945
1
1887-1956
1
1890-1980
1
1918-1964
1
19th century
1
Cambrian
1
Carboniferous
1
Devonian
1
Eocene
1
Mississippian
1
Oligocene
1
Ordovician
1
Paleocene
1
Pleistocene
1
Pliocene
1