Era
Cretaceous
57
Eocene
27
Tertiary
25
Precambrian
10
Paleocene
8
Paleozoic
6
Triassic
6
Carboniferous
5
Jurassic
5
Permian
5
Proterozoic
5
Devonian
4
Pennsylvanian
4
Pleistocene
4
Pliocene
4
Archaean
3
Cenozoic
3
Miocene
3
Quaternary
3
Cambrian
2
Mesozoic
2
Mississippian
2
Paleogene
2
1829-1887
1
1860-1890
1
19th century
1
Dovanian
1
Holocene
1