Turonian
second stage and age of the Upper Cretaceous series/Late Cretaceous epoch
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 ± 0.2 Ma and 89.8 ± 0.3 Ma (million years ago). The Turonian is preceded by the Cenomanian Stage and underlies the Coniacian Stage.
At the beginning of the Turonian an oceanic anoxic event (OAE 2) took place, also referred to as the Cenomanian-Turonian boundary event or the "Bonarelli Event". Sea level fall took place in the latter part of the Turonian from the highstand at the beginning of the Turonian.
Stratigraphic definition
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).
The top of the Turonian Stage (the base of the Coniacian) is defined as the place in the stratigraphic column where the inoceramid bivalve species Cremnoceramus rotundatus first appears.
This brief starts where responsible research should: with the source description of “Turonian” as second stage and age of the Upper Cretaceous series/Late Cretaceous epoch. Everything that follows is an evidence route, not borrowed authority.
Why this record matters
The subject matters to the general reference register because the source frames it as second stage and age of the Upper Cretaceous series/Late Cretaceous epoch. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Jan 2, 2026. The linked authority identifier is Q691429. Authority coordinates are 38.282, -104.728. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank. The first chronological checks are 1802, 1857 and 1842.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Turonian”, its source revision and the description used here.
- Expand the search: follow Turonian primary sources, Turonian archive and Turonian research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Turonian”?
- Which institution is responsible for the underlying evidence?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Turonian” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.