The Santonian is an
age in the
geologic timescale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...
or a
chronostratigraphic stage. It is a subdivision of the
Late Cretaceous Epoch or
Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (
million years ago) and 83.6 ± 0.7 mya. The Santonian is preceded by the
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...
and is followed by the
Campanian.
[Gradstein ''et al.'' (2004)]
Stratigraphic definition
The Santonian Stage was established by
French
French (french: français(e), link=no) may refer to:
* Something of, from, or related to France
** French language, which originated in France, and its various dialects and accents
** French people, a nation and ethnic group identified with Franc ...
geologist
Henri Coquand in 1857. It is named after the city of
Saintes in the region of
Saintonge
Saintonge may refer to:
*County of Saintonge, a historical province of France on the Atlantic coast
*Saintonge (region), a region of France corresponding to the historical province
Places
*Saint-Genis-de-Saintonge, a commune in the Charente-Mari ...
, where the original
type locality
Type locality may refer to:
* Type locality (biology)
* Type locality (geology)
See also
* Local (disambiguation)
* Locality (disambiguation)
{{disambiguation ...
is located.
The base of the Santonian Stage is defined by the appearance of the
inoceramid bivalve
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
''
Cladoceramus undulatoplicatus
''Cladoceramus'' is an extinct genus of fossil Marine (ocean), marine pteriomorphian bivalves that superficially resembled the related winged pearly oysters of the Extant taxon, extant genus ''Pteria (bivalve), Pteria''. They lived in the Santoni ...
''. The
GSSP (official reference profile) for the base of the Santonian Stage is located near
Olazagutia, Spain; it was ratified by the Subcommission on Cretaceous Stratigraphy in 2012.
The Santonian's top (the base of the Campanian Stage) is informally marked by the
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
ion of the
crinoid ''
Marsupites testudinarius''.
, a GSSP for the top of the Santonian has not been ratified.
Subdivision
The Santonian is sometimes subdivided into Lower, Middle and Upper Substages. In the
Tethys domain the Santonian is coeval with a single
ammonite
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
biozone: that of ''
Placenticeras polyopsis''.
Biostratigraphy based on inoceramids,
nanoplankton or
forams is more detailed.
References
Notes
Literature
*; 2004: ''A Geologic Time Scale 2004'',
Cambridge University Press.
External links
GeoWhen Database - SantonianLate Cretaceous timescale
at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Late Cretaceous
at the website of Norges Network of offshore records of geology and stratigraphy
{{Geological history, p, m
*04
Geological ages
Cretaceous geochronology