Santonian

Santonian
	86.3 ± 0.5 – 83.6 ± 0.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
	Key events in the Cretaceous -140 — – -130 — – -120 — – -110 — – -100 — – -90 — – -80 — – -70 — – M; e; s; o; z; o; i; c C; Z J C; r; e; t; a; c; e; o; u; s P; g L; J E; a; r; l; y L; a; t; e P; C Tithonian Berriasian Valanginian Hauterivian Barremian Aptian Albian Cenoman. Turonian Coniacian Santonian Campanian Maastricht. Danian ← K-Pg mass; extinction An approximate timescale of key Cretaceous events.; Axis scale: millions of years ago.;
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	FAD of the Inoceramid Bivalve Cladoceramus undulatoplicatus
Lower boundary GSSP	Olazagutia, Spain; 42.8668°N 2.1968°W
GSSP ratified	January 2013[1]
Upper boundary definition	Not formally defined
Upper boundary definition candidates	LAD of the Crinoid Marsupites testudinarius
Upper boundary GSSP candidate section(s)	Seaford Head, Sussex, England, UK; Waxahachie dam spillway, Texas, USA;

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]

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.

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.

Ankylosaurs of the Santonian
Taxa	Presence	Location	Description	Images
Hungarosaurus[4]
Niobrarasaurus
Pinacosaurus
Tsagantegia

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

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

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

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

Ornithopods of the Santonian
Taxa	Presence	Location	Description	Images
†Arstanosaurus				Claosaurus Gryposaurus
†Claosaurus[4]
†Eotrachodon
†Gryposaurus
†Lophorhothon
†Nipponosaurus

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

Pterosaurs of the Santonian
Taxa	Presence	Location	Description	Images
†Aralazhdarcho				Reconstruction of Bakonydraco
†Bakonydraco
†Caiuajara
†Samrukia

Sauropods of the Santonian
Taxa	Presence	Location	Description	Images
Microcoelus	Santonian-Campanian	Bajo de la Carpa Formation, Argentina
Quaesitosaurus
Sonidosaurus

Squamates of the Santonian
Taxa	Presence	Location	Description	Images
†Eonatator				Eonatator Reconstruction of Tylosaurus, a mosasaur
†Madtsoia †Madtsoia madagascariensis[5]
†Pannoniasaurus
†Tylosaurus

†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

Lamolda, M.; Paul, C.; Peryt, D.; Pons, J. (March 2014). "The Global Boundary Stratotype and Section Point (GSSP) for the base of the Santonian Stage, "Cantera de Margas", Olazagutia, northern Spain". Episodes. 37 (1): 2–13. doi:10.18814/epiiugs/2014/v37i1/001. Retrieved 24 December 2020.
Gradstein et al. (2004)
"GeoWhen Database - Barremian". Archived from the original on 2007-10-22. Retrieved 2007-12-02. Version 1.1.0.
Only known from this stage
Dating uncertain

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

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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