Era
Cretaceous
64
Precambrian
35
Tertiary
24
Jurassic
23
Triassic
22
Eocene
20
Paleozoic
16
Pennsylvanian
13
Quaternary
13
Cenozoic
12
Permian
11
Holocene
5
Pleistocene
5
Mesozoic
4
Miocene
3
Mississippian
3
1834-1902
2
Carboniferous
2
Devonian
2
Oligocene
2
Paleocene
2
Paleogene
2
1829-1887
1
Pliocene
1