Santonian

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System Series Stage Age (Ma)
Paleogene Paleocene Danian younger
Cretaceous 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
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 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 85.8 ± 0.7 mya (million years ago) and 83.5 ± 0.7 mya. The Santonian is preceded by the Coniacian and is followed by the Campanian.[1]

Stratigraphic definition[edit]

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[edit]

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[edit]

†Ankylosaurs[edit]

Ankylosaurs of the Santonian
Taxa Presence Location Description Images

Birds (avian theropods)[edit]

Birds of the Santonian
Taxa Presence Location Description Images

Apatornis[4]

Neuquenornis[3]

Parahesperornis[4]

Patagopteryx[3]

Cartilaginous Fish[edit]

Cartilaginous Fish of the Santonian
Taxa Presence Location Description Images

†Ceratopsians[edit]

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

Crocodylomorphs[edit]

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

Mammals[edit]

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

†Ornithopods[edit]

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

†Plesiosaurs[edit]

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

†Pterosaurs[edit]

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

†Sauropods[edit]

Sauropods of the Santonian
Taxa Presence Location Description Images

Squamates[edit]

Squamates of the Santonian
Taxa Presence Location Description Images

Eonatator

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

Pannoniasaurus

Tylosaurus

†Theropods (non-avian)[edit]

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

Achillesaurus[3]

Achillobator

Alectrosaurus

Aucasaurus[3]

Flora[edit]

Advanced dicotyledons

References[edit]

Notes[edit]

  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. ^ a b c d e f g Only known from this stage
  4. ^ a b c d e Dating uncertain

Literature[edit]

External links[edit]

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