Era
Civil War, 1861-1865
7
20th century
5
1876-1950
4
1839-1916
2
21st century
2
Cretaceous
2
Devonian
2
Mesozoic
2
1803-1885
1
1830-1914
1
1831-1874
1
1839-1911
1
1850-1910
1
1852-1943
1
1854-1922
1
1871-1948
1
1875-1965
1
1877-
1
1880
1
1893-1992
1
1895-1983
1
1908-1991
1
1913-1921
1
1921-1930
1
1925-1968
1
1929-1968
1
1939-
1
1951-
1
1952-
1
1971-
1
19th century
1
2001-2009
1
Carboniferous
1
Jurassic
1
Paleozoic
1
Pleistocene
1
Pliocene
1
Quaternary
1
Tertiary
1