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.[2]

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 ICS, as of 2017.[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.[3] 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
Ankylosaurs of the Santonian
Taxa Presence Location Description Images

Birds (avian theropods)
Birds of the Santonian
Taxa Presence Location Description Images

†Apatornis[5]

†Neuquenornis[4]

†Parahesperornis[5]

†Patagopteryx[4]

Cartilaginous Fish
Cartilaginous Fish of the Santonian
Taxa Presence Location Description Images
  • †Hexanchus microdon
  • †Notidanodon
  • †Notidanoides[5]

†Ceratopsians
Ceratopsians of the Santonian
Taxa Presence Location Description Images
Graciliceratops

Crocodylomorphs
Crocodylomorphs of the Santonian
Taxa Presence Location Description Images
Mid-Late Santonian Bajo de la Carpa Formation, Patagonia, Argentina
Reconstruction of Comahuesuchus
Reconstruction of Notosuchus
Csehbánya Formation, Bakony Mountains, Hungary
Mid-Late Santonian Bajo de la Carpa Formation, Patagonia, Argentina
Santonian-Campanian Gobi desert, Mongolia

Mammals
Mammals of the Santonian
Taxa Presence Location Description Images
  • Paracimexomys
  1. †Paracimexomys magister[4]

†Ornithopods
Ornithopods of the Santonian
Taxa Presence Location Description Images
Claosaurus
Gryposaurus

†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
Santonian-Campanian Bajo de la Carpa Formation, Argentina

Squamates
Squamates of the Santonian
Taxa Presence Location Description Images

†Eonatator
Eonatator
Reconstruction of Tylosaurus, a mosasaur
  1. †Madtsoia madagascariensis[5]

†Pannoniasaurus

†Tylosaurus

†Theropods (non-avian)
†Non-avian theropods of the Santonian
Taxa Presence Location Description Images

†Achillesaurus[4]
Achillesaurus
Achillobator
Aucasaurus
Erlikosaurus
Xixiasaurus

†Achillobator

†Alectrosaurus

†Aucasaurus[4]

†Erlikosaurus

†Gigantoraptor

†Thanos

†Xixiasaurus

Flora
gollark: I may need an "incdec-rs".
gollark: Yes, it seems like under heavy load people get dropped somehow?
gollark: Incdec is a cool fixpoint.
gollark: I have deployed apiobots to rectify its value.
gollark: No.

References

Notes
  1. Super User. "ICS - Chart/Time Scale". www.stratigraphy.org.
  2. Gradstein et al. (2004)
  3. "GeoWhen Database - Barremian". Archived from the original on 2007-10-22. Retrieved 2007-12-02. Version 1.1.0.
  4. Only known from this stage
  5. Dating uncertain

Literature
  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
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