Period Subperiod Stage Age (Ma)
(date for upper
boundary)
Cretaceous Late Cretaceous Maastrichtian 65.0
Campanian 74.0
Santonian 83.0
Coniacian 86.6
Turonian 88.5
Cenomanian 90.4
Early Cretaceous Albian 97.0
Aptian 112.0
Barremian 124.5
Hauterivian 131.8
Valanginian 135.0
Berriasian 140.7
Jurassic Late Jurassic Tithonian 145.6
Kimmeridgian 152.1
Oxfordian 154.7
Middle Jurassic Callovian 157.1
Bathonian 161.3
Bajocian 166.1
Aalenian 173.5
Early Jurassic Toarcian 178.0
Pliensbachian 187.0
Sinemurian 194.5
Hettangian 203.5
Triassic Late Triassic Rhaetian 208.0
Norian 209.5
Carnian 223.4
Middle Triassic Ladinian 235.0
Anisian 239.5
Early Triassic Spathian 241.1
Nammalian 241.9
Griesbachian 243.4
and the Permo-Triassic (=Changxingian-Griesbachian) boundary is at 245.0
Source: A Geologic Time Scale 1989 (Harland et al., 1990, Cambridge Univ.
Press)
Thomas R. Holtz, Jr. tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile Phone: 703-648-5280
U.S. Geological Survey FAX: 703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA 22092
U.S.A.