Valanginian

In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma (million years ago). The Valanginian stage succeeds the Berriasian stage of the Lower Cretaceous and precedes the Hauterivian stage of the Lower Cretaceous.^[1]

Stratigraphic definitions

The Valanginian was first described and named by Édouard Desor in 1853. It is named after Valangin, a small town north of Neuchâtel in the Jura Mountains of Switzerland.

The base of the Valanginian is at the first appearance of calpionellid species Calpionellites darderi in the stratigraphic column. A global reference section (a GSSP) had in 2009 not yet been appointed.

The top of the Valanginian (the base of the Hauterivian) is at the first appearance of the ammonite genus Acanthodiscus.

Subdivision

The Valanginian is often subdivided in Lower and Upper substages. The Upper substage begins at the first appearance of ammonite species Saynoceras verrucosum and the major transgression Va3.

In the Tethys domain, the Valanginian stage contians five ammonite biozones:

• zone of Criosarasinella furcillata
• zone of Neocomites peregrinus
• zone of Saynoceras verrucosum
• zone of Busnardoites campylotoxus
• zone of Tirnovella pertransiens

Palaeontology

Ankylosaurs

Birds

Crocodylomorphs

Crocodylomorphs of the Valanginian
Taxa	Presence	Location	Description	Images
Dakosaurus lapparenti[3]				Dakosaurus Enaliosuchus
Enaliosuchus[3]
Machimosaurus

Ornithopods

Ornithopoda of the Valanginian
Taxa	Presence	Location	Description	Images
Fulgurotherium		Australia	May be a chimera based on multiple species of ornithopods.	Iguanodon Lanzhousaurus
Iguanodon		Europe, North America
Kangnasaurus		Cape Province, South Africa	Generally considered nomen dubium, it classified as a genus similar to Dryosaurus, i.e. an iguanodont.
Lanzhousaurus		Lanzhou, Gansu, China	Notable for its "astonishingly huge teeth", among the largest for any herbivorous creature ever, which indicate it is an iguanodont. The mandible, longer than one meter, suggests very large size for the animal.
Valdosaurus		Isle of Wight, England; Niger, Africa	A dryosaurid

Pterosaurs

Pterosaurs of the Valanginian
Taxa	Presence	Location	Description	Images
Lonchodectes				Pterodaustro
Pterodaustro		Lagarcito Formation, San Luis Province, Argentina; Chile

Sauropods

Stegosaurs

Theropods

References

Notes

Literature

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

External links

• GeoWhen Database - Valanginian
• Mid-Cretaceous timescale and ühttp://stratigraphy.science.purdue.edu/charts/Timeslices/5_JurCret.pdf Jurassic-Cretaceous timescale], at the website of the subcommission for stratigraphic information of the ICS
• Stratigraphic chart of the Lower Cretaceous, at the website of Norges Network of offshore records of geology and stratigraphy

This geochronology article is a stub. You can help Wikipedia by expanding it. v • d • e