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