Era
20th century
106
19th century
52
21st century
22
Cretaceous
21
Tertiary
16
1847-1931
15
Paleozoic
11
Precambrian
11
Pennsylvanian
10
1902-1974
9
1867-1912
8
1871-1948
8
18th century
8
Mississippian
8
1949-
7
Permian
7
Quaternary
7
1843-1942
6
1856-1943
6
1895-1983
6
1903-1975
6
1452-1519
4
16th century
4
1873-1961
4
1879-1973
4
1892-1926
4
1945-
4
Cenozoic
4
Devonian
4
Ordovician
4
Paleocene
4
17th century
3
1814-1862
3
1815-1879
3
1856-1915
3
1864-1946
3
1874-1940
3
1886-1958
3
1890-1954
3
1890-1976
3
1891-1968
3
1891-1971
3
1900-1993
3
1921-2016
3
1935-
3
1953-
3
1970-
3
Jurassic
3
To 1500
3
Triassic
3
more ...