Santonian

System/
Period		 Series/
Epoch		 Stage/
Age		 Age (Ma)
Paleogene Paleocene Danian younger
Cretaceous Upper/
Late		 Maastrichtian 66.0–72.1
Campanian 72.1–83.6
Santonian 83.6–86.3
Coniacian 86.3–89.8
Turonian 89.8–93.9
Cenomanian 93.9–100.5
Lower/
Early		 Albian 100.5–~113.0
Aptian ~113.0–~125.0
Barremian ~125.0–~129.4
Hauterivian ~129.4–~132.9
Valanginian ~132.9–~139.8
Berriasian ~139.8–~145.0
Jurassic Upper/
Late		 Tithonian older
Subdivision of the Cretaceous system
according to the IUGS, as of July 2012.

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.[1]

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.[2] 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, nannoplankton or forams is more detailed.

Paleontology

†Ankylosaurs

Ankylosaurs of the Santonian
Taxa Presence Location Description Images

Birds (avian theropods)

Birds of the Santonian
Taxa Presence Location Description Images

†Apatornis[4]

†Neuquenornis[3]

†Parahesperornis[4]

†Patagopteryx[3]

Cartilaginous Fish

Cartilaginous Fish of the Santonian
Taxa Presence Location Description Images
  • †Hexanchus microdon
  • †Notidanodon
  • †Notidanoides[4]

†Ceratopsians

Ceratopsians of the Santonian
Taxa Presence Location Description Images
Graciliceratops
Reconstruction of Udanoceratops

Crocodylomorphs

Crocodylomorphs of the Santonian
Taxa Presence Location Description Images
Reconstruction of Notosuchus, a relative of the crocodiles

Mammals

Mammals of the Santonian
Taxa Presence Location Description Images
  • Paracimexomys
  1. †Paracimexomys magister[3]

†Ornithopods

Ornithopods of the Santonian
Taxa Presence Location Description Images
Claosaurus
Gryposaurus
Reconstruction of Nipponosaurus, a duck-billed dinosaur

†Plesiosaurs

Plesiosauria of the Santonian
Taxa Presence Location Description Images
Dolichorhynchops osborni from Coniacian to Campanian Fort Hays Limestone, Kansas, USA
Reconstruction of Dolichorhynchops

†Pterosaurs

Pterosaurs of the Santonian
Taxa Presence Location Description Images
Reconstruction of Bakonydraco

†Sauropods

Sauropods of the Santonian
Taxa Presence Location Description Images

Squamates

Squamates of the Santonian
Taxa Presence Location Description Images

†Eonatator
Reconstruction of Tylosaurus, a mosasaur
  1. †Madtsoia madagascariensis[4]

†Pannoniasaurus

†Tylosaurus

†Theropods (non-avian)

†Non-avian theropods of the Santonian
Taxa Presence Location Description Images

†Achillesaurus[3]

†Achillobator

†Alectrosaurus

†Aucasaurus[3]

Flora

Advanced dicotyledons

References

Notes

  1. ↑ Gradstein et al. (2004)
  2. ↑ "GeoWhen Database - Barremian". Archived from the original on 2007-10-22. Retrieved 2007-12-02. Version 1.1.0.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Only known from this stage
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Dating uncertain

Literature

External links

Cretaceous Period
Lower/Early Cretaceous Upper/Late Cretaceous
Berriasian | Valanginian | Hauterivian
Barremian| Aptian | Albian		 Cenomanian | Turonian | Coniacian
Santonian |Campanian | Maastrichtian