| System (period) | Series (epoch) | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Paleogene | Paleocene | Danian | 66,0 | |
| Cretaceous | Upper (Late) | Maastrichtian |  72.1±0.2
| |
| Campanian | 83.6±0.2
| |||
| Santonian | 86.3±0.5
| |||
| Coniacian | 89.8±0.3
| |||
| Turonian | 93.9
| |||
| Cenomanian | 100.5
| |||
| Lower (Early) | Albian | ~113.0
| ||
| Aptian | ~121.4 | |||
| Barremian | 125.77* | |||
| Hauterivian | ~132.6
| |||
| Valanginian | ~139.8 | |||
| Berriasian | ~145.0 | |||
| Jurassic | Upper | Tithonian | older | |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] *A golden spike is seen in chart but not ratified yet. | ||||
The Valanginian is a second stage of the Lower Cretaceous series, corresponding to the Valanginian age of the Early Cretaceous epoch. It lasted from approximately 139.8 Ma to around 132.6 Ma (million years ago). It is preceded by the Berriasian and is followed by the Hauterivian.
Definition[]
As of 2024, there is no GSSP defining the base of the Valanginian stage. A candidate is a section near Caravaca in Spain, with the first appearance of calpionellid Calpionellites darderi as the marker of the lower boundary.[2]
Valanginian life[]
The diversity of cephalopods was preserved. Ammonites are well known for their fossilized shells, which are found throughout the world. Valanginian genera include Dobrodgeiceras, Olcostephanus, Bochianites, Neocomites and Thurmanniceras. Along with them lived related Nautilids , which also had rounded external shells. One of the Valanginian nautilids is Cymatoceras. Another group of cephalopods are belemnites, which had cone-shaped internal rostra. Belemtines of the genera Hibolithes, Pseudobelus and Duvalia have been found in the Valanginian of Rhône-Alpes, France. Ichthyosaurs hunted cephalopods. Many of ichthyosaurian groups become extint by this time, but ophthalmosaurids like Aegirosaurus remained quite numerous.
Sauropterygians were still widespread. Rising sea levels have led some of them to switch to living in fresh waters. Hastanectes was found in the lacustrine sediments of the Valanginian Wadhurst Clay Formation in the United Kingdom. A turtle Hylaeochelys and ornithopod dinosaurs Barilium and Hypselospinus were also found here as well as well as a tooth of a theropod known as "Megalosaurus" dunkeri.
Valanginian sauropods include Haestasaurus from the UK and Cedarosaurus and Moabosaurus from Utah, USA. Ankylosaurs like North American Gastonia fed on low vegetation. A small theropod Nedcolbertia is a possible ornithomimosaur, although its current classification is unclear. Utahraptor, a large dromaeosaurid, existed during this age in North America.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Mesozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=35.