| 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 Early Cretaceous epoch (geochronological name) or the Lower Cretaceous series (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is considered to stretch from 145 Ma to 100.5 Ma (IUGS 2023), between the Tithonian age of the Late Jurassic and the Cenomanian age of the Late Cretaceous. It is characterized by the spreading of the ornithopods, ankylosaurs, coelurosaurs and titanosaurian sauropods.
Definition[]
As of 2024, there is still no GSSP defining the base of the Lower Cretaceous, the Berriasian stage and the whole Cretaceous system. As it said by Alekseev A. S. (Lomonosov Moscow State University) in 2013, "the search process and confirmation of the Jurassic-Cretaceous boundary has long become a joke".[2] The possible candidate is a section at Tré Maroua, Hautes–Alpes, France, with the base of Calpionella alpina Subzone for the lower boundary.[3]
Subdivisions[]
The Lower Cretaceous series is divided into six stages: Berriasian, Valanginian, Hauterivian, Barremian, Aptian and Albian. In geochronology, all correspond to the ages of the same names within the Early Cretaceous epoch. The Albian is the longest age of the Cretaceous with the duration of 12.5 million years (from ~113 to 100.5 Ma).
Early Cretaceous life[]
Several groups, common in the Jurassic, were extinct at the beginning or during this epoch. Temnospondyls, thalattosuchians, non-pterodactyloid pterosaurs, non-abelisauroid ceratosaurs, stegosaurs and probably the last non-mammalian therapsids dissapeared in the Early Cretaceous.
In general, pterosaurs became even more numerous, some of them adapted to feeding on plants, such as the tapejarids.
Dinosaurs became more diverse with many specialized forms emerged after Jurassic. The most successful dinosaurian group since the Early Cretaceous is Coelurosauria, a taxon including ornithomimosaurians, tyrannosauroids, therizinosaurians, dromaeosaurids and avialans with the bird branch being more numerous than mammals today.
List of life forms[]
Early Cretaceous dinosaurian genera include:
- Acrocanthosaurus
- Astrodon
- Baryonyx
- Caudipteryx
- Deinonychus
- Hylaeosaurus
- Hypsilophodon
- Iberomesornis
- Iguanodon
- Liaoningornis
- Microraptor
- Neovenator
- Ouranosaurus
- Psittacosaurus
- Sauroposeidon
- Sinosauropteryx
- Tenontosaurus
- Utahraptor
- Wuerhosaurus
- Zephyrosaurus
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ Alekseev A. S. (2013) "Current state of International Stratigraphic Chart: Positive and negative consequences for the general stratigraphic scale of Russia". (in Russian) General stratigraphic scale of Russia: current state and ways of perfection. All-Russian meeting. Page 11. ISBN 978-5-98709-394-8 Archived copy
- ↑ "GSSP Table - Mesozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=35.