The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by the Cenomanian Stage and underlies the Coniacian Stage.
|Regional usage||Global (ICS)|
|Time scale(s) used||ICS Time Scale|
|Time span formality||Formal|
|Lower boundary definition||FAD of the Ammonite Watinoceras devonense|
|Lower boundary GSSP||Rock Canyon, Colorado, USA|
|GSSP ratified||September 2003|
|Upper boundary definition||Not formally defined|
|Upper boundary definition candidates||FAD of the Inoceramid Bivalve Cremnoceramus rotundatus|
|Upper boundary GSSP candidate section(s)|
The Turonian (French: Turonien) was defined by the French paleontologist Alcide d'Orbigny (1802–1857) in 1842. Orbigny named it after the French city of Tours in the region of Touraine (department Indre-et-Loire), which is the original type locality.
The base of the Turonian Stage is defined as the place where the ammonite species Watinoceras devonense first appears in the stratigraphic column. The official reference profile (the GSSP) for the base of the Turonian is located in the Rock Canyon anticline near Pueblo, Colorado (United States, coordinates: 38° 16' 56" N, 104° 43' 39" W).
- zone of Subprionocyclus neptuni (in the Upper Turonian)
- zone of Collignoniceras woollgari (in the Middle Turonian)
- zone of Mammites nodosoides
- zone of Watinoceras coloradoense or Watinoceras devonense (last two both in the Lower Turonian)
- International Commission on Stratigraphy. "ICS - Chart/Time Scale". www.stratigraphy.org.
- Kennedy, W. J.; I. Walaszczyk; W. A. Cobban (2005). "The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A." (PDF). Episodes. 28 (2): 93–104. doi:10.18814/epiiugs/2005/v28i2/003.
- See Gradstein et al. (2004) for a detailed description of the ICS' timescale
- The GSSP was established by Kennedy et al. (2005)
- Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
- Kennedy, W.J.; Walaszczyk, I. & Cobban, W.A.; 2005: The Global Boundary Stratotype Section and Point for the base of the Turonian Stage of the Cretaceous: Pueblo, Colorado, U.S.A., Episodes 28(2): pp 93–104.
- GeoWhen Database - Turonian
- Late Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
- Stratigraphic charts of the Cretaceous:  and , at the website of Norges Network of offshore records of geology and stratigraphy
- Turonian Microfossils: 48 images of Foraminifera