| 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. | ||||
Barremian sedimentary rock layers in France
The Barremian is a fourth stage of the Lower Cretaceous series, corresponding to the Barremian age of the Early Cretaceous epoch. It lasted from approximately 125.77 Ma to around 121.4 Ma (million years ago). It is preceded by the Hauterivian age and is followed by the Aptian age.
The diverse Las Hoyas biota existed during this age.
Definition[]
Although the September 2023 version of International Chronostratigraphic Chart shows a golden spike near this stage,[2] there is actually no GSSP for the Barremian as of 2024.[3] There is a candidate, a section in Murcia Province, Spain, and the first appearance of the ammonites of Taveraidiscus hugii - Spitidiscus vandeckii group define the base of this stage.[3]
Barremian life[]
The seas were inhabited by lost of cephalopods. Ammonites like Hamulinites, Acrioceras, Psilotissotia and Barremites were hunting small fish in the water column. Ichthyosaurs like Simbirskiasaurus, Platypterygius and Sveltonectes lived exclusively in the seas and also fed mainly on small animals. Pliosaurids were still common. Barremian genera include Brachauchenius, Acostasaurus and Stenorhynchosaurus.
Amargasaurus sketeton
Large number of continental animals are known from the Barremian sediments. Amargasaurus, a sauropod with spiked neck, lived in what is now Neuquen, Argentina, alongside with Amargasuchus, a possible terrestrial crocodylomorph. In Europe, a large theropod Baryonyx hunted fish like Lepidotes and ornithopods such as Iguanodon and Mantellisaurus.
Liaoning biota[]
Numerous mammals and dinosaurs lived on the territory of modern Liaoning, China. Large, feathered Yutyrannus hunted Ruixinia, a mid-sized sauropod. Small theropods like Sinusonasus, Graciliraptor, Sinovenator and Mei preferred smaller prey like Jeholosaurus and Psittacosaurus.
Repenomamus and caprured Psittacosaurus
Many theropods of this location are known to have feathers. This feature is present in both avian (Hongshanornis, Confuciusornis, Longicrusavis etc.) and non-avian (Sinosauropteryx, Protarchaeopteryx etc.) theropods. One of the possible reasons for the appearance and development of plumage is adaptation to a cold climate, although Liaoning area was not located in polar region during Barremian. Feathered Caudipteryx, Protarchaeopteryx and Incisivosaurus were possibly herbivores or omnivores, and lizards (such as Dalinghosaurus) and mammals could have been the part of their diet. However, some mammals like Repenomamus and Gobiconodon were large enough to hunt the dinosaurs themselves. Pterosaurs including Pterofiltrus, Yixianopterus and Moganopterus also lived there.
Las Hoyas biota[]
One of the most diverse prehistoric biotas in the world is represented at the site of Las Hoyas in Spain. Over 20 000 plant and animal fossils[4] were found in lacustrine (lake) sediments formed in subtropical conditions in the Barremian age. Invertebrate fauna includes numerous crustaceans, arachnids and insects of the orders Hemiptera, Coleoptera, Diptera, Hymenoptera and Odonata.
Concavenator chasing Pelecanimimus
Vertebrates of Las Hoyas are also diverse. The lakes were inhabited by fish of the orders Semionotiformes (Notagogus), Lepisosteiformes (Lepidotes), Amiiformes (Amiopsis, Caturus, Vidalamia), Pycnodontiformes (Macromesodon, Coelodus, Eomesodon), Leptolepidiformes (Leptolepis) and others. Amphibians of Las Hoyas include Celtedens and more derived caudatans (Hylaeobatrachus, Valdotriton) and frog relatives (Gracilibatrachus, Iberobatrachus).
The sediments contain a large number of sauropsids from turtles (Hoyasemys) to squamates (Scandensia, Meyasaurus etc.) and archosaurs. crocodylomorphs like Montsecosuchus were hunted near water. Pelecanimimus, an ornithomimosaurian dinosaur, lived near the shallows, where it caught small fish and amphibians. The apex predator of the ecosystem was a carcharodontosaurid Concavenator. Important finds were small enantiornithine birds Concornis, Iberomesornis and Eoalulavis that probably lived in the forests on the lake shore. Pterosaurs including Europejara have also been found here.
Finally, Spinolestes, a gobiconodontid mammal, lived in this area. With a skull length about 3 cm, it was small in comparison with such relatives as Repenomamus from the same age.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "International Chronostratigraphic Chart (September 2023)". International Commission on Stratigraphy. https://stratigraphy.org/ICSchart/ChronostratChart2023-09.pdf. (archived copy)
- ↑ 3.0 3.1 "GSSP Table - Mesozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=35.
- ↑ Jesús Marugán-Lobón, Hugo Martín-Abad, Ángela D. Buscalioni (2023) "The Las Hoyas Lagerstätte: a palaeontological view of an Early Cretaceous wetland". Journal of the Geological Society, vol. 183. DOI:10.1144/jgs2022-07