Historical Period
20th century
4
1861-1944
2
1927-2010
2
1989-1993
2
2001-2009
2
2003-
2
21st century
2
Cretaceous
2
1819-1880
1
1874-1947
1
1888-1953
1
1890-1932
1
1910-1936
1
1921-1923
1
1924
1
1940-
1
1981-
1
19th century
1
2001-
1
Cenozoic
1
Eocene
1
Mississippian
1
Neogene
1
Paleocene
1
Paleozoic
1
Permian
1
S XX
1