Era
Cretaceous
24
Eocene
13
Precambrian
9
Permian
8
Tertiary
8
Carboniferous
4
Paleocene
4
Jurassic
3
Mesozoic
3
Paleozoic
3
Pennsylvanian
3
Proterozoic
3
Triassic
3
Archaean
2
Devonian
2
Pleistocene
2
1829-1887
1
1859-1952
1
1860-1890
1
19th century
1
Cenozoic
1
Holocene
1
Miocene
1
Paleogene
1
Quaternary
1