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]

Age (Ma)
Paleogene Paleocene Danian younger
Cretaceous Upper/
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
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/
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.


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

Birds (avian theropods)

Birds of the Santonian
Taxa Presence Location Description Images





Cartilaginous Fish

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



Notosuchus BW
Reconstruction of Notosuchus


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


Nipponosaurus dinosaur
Reconstruction of Nipponosaurus, a duck-billed dinosaur


Dolichorhynchops BW
Reconstruction of Dolichorhynchops


Reconstruction of Bakonydraco


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


Tylosaurus pembinensis 1DB
Reconstruction of Tylosaurus, a mosasaur

†Theropods (non-avian)




  1. ^ Super User. "ICS - Chart/Time Scale".
  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. ^ a b c d e f g Only known from this stage
  5. ^ a b c d Dating uncertain


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

External links


Aucasaurus was a genus of medium-sized theropod dinosaur from Argentina that lived during the Late Cretaceous (Santonian to Campanian stage) of the Anacleto Formation. It was smaller than the related Carnotaurus, although more derived in some ways, such as its extremely reduced arms and almost total lack of fingers.

The type skeleton is complete to the thirteenth caudal vertebra, and so is relatively well understood, and is the most complete abelisaurid yet described. However, the skull is damaged, causing some paleontologists to speculate that it was involved in a fight prior to death.


Bonitasaura is a titanosaurian dinosaur hailing from uppermost layers of the Late Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén Group of the eastern Neuquén Basin, located in Río Negro Province, Northwestern Patagonia, Argentina. The remains, consisting of a partial sub-adult skeleton jumbled in a small area of fluvial sandstone, including lower jaw with teeth, partial vertebrae series and limb bones, were described by Sebastian Apesteguía in 2004.

The genus name Bonitasaura refers to the fossil quarry’s name, "La Bonita", while the name of the type species, B. salgadoi, pays homage to Leonardo Salgado, a renowned Argentine palaeontologist.


Comahuesuchus is an extinct genus of notosuchian crocodylomorphs from the Santonian Bajo de la Carpa Formation of Argentina. It was described by palaeontologist José Bonaparte in 1991. The type species is C. brachybuccalis.


The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by the Turonian and followed by the Santonian.


Cynodontosuchus is an extinct genus of baurusuchid mesoeucrocodylian. Fossils have been found from Argentina of Late Cretaceous age from the Bajo de la Carpa Formation (dating back to the Santonian) as well as the Pichi Picun Leufu Formation (dating back to the Coniacian and Santonian). Fossils also have been found in the Tiupampan Santa Lucía Formation of Bolivia.


Dermochelyidae is a family of turtles which has seven extinct genera and one extant genus, including the largest living sea turtles.


Elaeaocarpaceae is a family of flowering plants. The family contains approximately 615 species of trees and shrubs in 12 genera. The largest genera are Elaeocarpus, with about 350 species, and Sloanea, with about 150.

The species of Elaeocarpaceae are mostly tropical and subtropical, with a few temperate-zone species. Most species are evergreen. They are found in Madagascar, Southeast Asia, Australia, New Zealand, West Indies, and South America.

The plants are hermaphrodite or dioecious and bear flowers clustered in inflorescences.

A phylogeny of the family, based on DNA sequences was published in 2006.Alkaloids Katavic 2005


Hadrosaurids (Greek: ἁδρός, hadrós, "stout, thick"), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The family, which includes ornithopods such as Edmontosaurus and Parasaurolophus, was a common group of herbivores during the Late Cretaceous Period in what is now Asia, Europe, Antarctica, South America, and North America. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout.

Like other ornithischians, hadrosaurids had a predentary bone and a pubic bone which was positioned backwards in the pelvis. Hadrosauridae is divided into two principal subfamilies: the lambeosaurines (Lambeosaurinae), which had hollow cranial crests or tubes; and the saurolophines (Saurolophinae), identified as hadrosaurines (Hadrosaurinae) in most pre-2010 works, which lacked hollow cranial crests (solid crests were present in some forms). Saurolophines tended to be bulkier than lambeosaurines. Lambeosaurines included the aralosaurins, tsintaosaurins, lambeosaurins and parasaurolophins, while saurolophines included the brachylophosaurins, kritosaurins, saurolophins and edmontosaurins.

Hadrosaurids were facultative bipeds, with the young of some species walking mostly on two legs and the adults walking mostly on four. Their jaws were evolved for grinding plants, with multiple rows of teeth replacing each other as the teeth wore down.


The Iguanidae are a family of lizards composed of iguanas and related species.


Mahuidacursor (meaning "mountain runner", mahuida meaning "mountain" in Mapudungun) is a genus of basal ornithopod dinosaur from the Santonian Bajo de la Carpa Formation of the Neuquén Basin in northern Patagonia, Argentina. The type and only species is M. lipanglef.


Microsuchus is an extinct genus of mesoeucrocodylians, belonging to Notosuchia. Fossils have been found in the Bajo de la Carpa Formation, dating to the Santonian stage of the Late Cretaceous.


Muyelensaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of Argentina. It was more slender than other titanosaurs. Fossils have been recovered from the Portezuelo Formation in the Neuquén province of Patagonia. The type species is M. pecheni. The name Muyelensaurus first appeared in a 2007 paper by Argentine paleontologists Jorge Calvo of the Universidad Nacional del Comahue and Bernardo González Riga of the Laboratorio de Paleovertebrados, and Brazilian paleontologist Juan Porfiri of the Universidade Federal do Rio de Janeiro.


Neuquensuchus (meaning "Neuquén crocodile", referring to the city) is an extinct genus of crocodyliform from the Santonian-age Upper Cretaceous Bajo de la Carpa Formation of Neuquén Province, Argentina. The known remains were discovered on the campus of Universidad Nacional del Comahue in the city of Neuquén. Neuquensuchus was named by Lucas E. Fiorelli and Jorge O. Calvo in a publication dated to 2007, but which became available in 2008. The type species is N. universitas, in recognition of its discovery locality. Unlike the great majority of crocodyliforms, its shin was longer than its thigh, suggesting it had some running ability.


Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebecosuchia is included within Notosuchia its existence is pushed into the Middle Miocene, about 11 million years ago. Fossils have been found from South America, Africa, Asia, and Europe. Notosuchia was a clade of terrestrial crocodilians that evolved a range of feeding behaviours, including herbivory (Chimaerasuchus), omnivory (Simosuchus), and terrestrial hypercarnivory (Baurusuchus). It included many members with highly derived traits unusual for crocodylomorphs, including mammal-like teeth, flexible bands of shield-like body armor similar to those of armadillos (Armadillosuchus), and possibly fleshy cheeks and pig-like snouts (Notosuchus). The suborder was first named in 1971 by Zulma Gasparini and has since undergone many phylogenetic revisions.


Notosuchidae is a Gondwanan family of notosuchians. They were small-bodied terrestrial crocodyliforms that lived during the Late Cretaceous.


Peirosauridae is a Gondwanan family of mesoeucrocodylians that lived during the Cretaceous period. It was a clade of terrestrial crocodyliforms that evolved a rather dog-like form, and were terrestrial carnivores. It was phylogenetically defined in 2004 as the most recent common ancestor of Peirosaurus and Lomasuchinae and all of its descendants. Lomasuchinae is a subfamily of peirosaurids that includes the genus Lomasuchus.Lomasuchinae was defined in the same 2004 study as the most recent common ancestor of Lomasuchus and Mahajangasuchini and all of its descendants. Mahajangasuchini, also constructed in the study, was defined as the most recent common ancestor of Mahajangasuchus and Uberabasuchus and all of its descendants. However, all more recent phylogenetic analyses placed Mahajangasuchus within its own family, Mahajangasuchidae, along with the newly named Kaprosuchus.


Petrobrasaurus is a genus of herbivorous sauropod dinosaur. It is a titanosaur which lived during the upper Cretaceous period (Santonian age) in what is now Rincón de los Sauces, Patagonia, Argentina. It is known from the holotype MAU-Pv-PH-449 — a partial disarticulated skeleton recovered from the Plottier Formation (Neuquén Basin), Argentina. This genus was named by Leonardo S. Filippi, José Ignacio Canudo, Leonardo J. Salgado, Alberto C. Garrido, Rodolfo A. Garcia, Ignacio A. Cerda and Alejandro Otero in 2011, and the type species is Petrobrasaurus puestohernandezi. The generic name is derived from "Petrobras" (oil company) and saurus, "lizard". The specific name refers to the Puesto Hernández oil field, where the fossil remains were found.


Yacarerani (meaning "first Yacare" in Guaraní) is an extinct genus of Late Cretaceous notosuchian crocodylomorph. Fossils have been found in 2002 in the Cajones Formation in Amboró National Park of central Bolivia and are Turonian-Santonian in age. The genus was recently described in 2009 in the Journal of Vertebrate Paleontology. The material represents two individuals and was found in association with eggs that are thought to have been part of a nest. Yacarerani was a small crocodylomorph at around 80 centimetres (31 in) in length. It may have lived in small groups, creating burrows to lay eggs in.


Yaminuechelys is an extinct genus of chelid turtle from Argentina. The genus first appeared during the Late Cretaceous, and then becomes extinct during the Late Paleocene.

Cenozoic era
(present–66.0 Mya)
Mesozoic era
(66.0–251.902 Mya)
Paleozoic era
(251.902–541.0 Mya)
Proterozoic eon
(541.0 Mya–2.5 Gya)
Archean eon (2.5–4 Gya)
Hadean eon (4–4.6 Gya)


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