Santonian

The Santonian is an age in the geologic timescale 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 and is followed by the Campanian.

Stratigraphic definition
The Santonian stage was established by French geologist Henri Coquand in 1857. It is named after the city of Saintes in the region of Saintonge, where the original type locality is located.

The base of the Santonian stage is defined by the appearance of the inoceramid bivalve Cladoceramus undulatoplicatus. Its top (the base of the Campanian stage) is marked by the extinction of the crinoid Marsupites testudinarius. In 2009, a GSSP (official reference profile) for both base and top had not yet been appointed.

Subdivision
The Santonian is sometimes subdivided into Lower, Middle and Upper substages. In the Tethys domain the Santonian is coeval with a single ammonite biozone: that of Placenticeras polyopsis. Biostratigraphy based on inoceramids, nanoplankton or forams is more detailed.

Paleontology

†Ankylosaurs

Birds (avian theropods)

Cartilaginous Fish

†Ceratopsians

Crocodylomorphs

Mammals

†Ornithopods

†Plesiosaurs

†Pterosaurs

†Sauropods

Squamates

†Theropods (non-avian)

Flora
Magnoliopsida
Advanced dicotyledons
Droseraceae: †Palaeoaldrovanda

References

Notes

Literature
; 2004: A Geologic Time Scale 2004, Cambridge University Press.

External links
GeoWhen Database - Santonian
Late 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

 
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Category:Geological ages
Category:Cretaceous geochronology