| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Triassic | Lower | Induan | 251.902±0.024 | |
| Permian | Lopingian | Changhsingian |  254.14±0.07
| |
| Wuchiapingian | 259.51±0.21
| |||
| Guadalupian | Capitanian | 264.28±0.16
| ||
| Wordian | 266.9±0.4
| |||
| Roadian | 273.01±0.14
| |||
| Cisuralian | Kungurian | 283.5±0.6 | ||
| Artinskian | 290.1±0.26
| |||
| Sakmarian | 293.52±0.17
| |||
| Asselian | 298.9±0.15
| |||
| Carb. | Pen. | Upper | Gzhelian | older |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Artinskian is a third stage of the Cisuralian series, corresponding to the Artinskian age of the Cisuralian epoch. It lasted from approximately 290.1 Ma to around 283.5 Ma (million years ago). It is preceded by the Sakmarian and is followed by the Kungurian.
Definition[]
The GSSP of the Artinskian stage was ratified in 2022. The lower boundary is fixed in the Dal’ny Tulkas section in the southern Urals, Russia, and related to the first appearance of the conodont species Sweetognathus asymmetricus.[2]
Artinskian life[]
The coastal shallows were inhabited by a variety of bivalves (Pseudomonotis, Acanthopecten, Parallelodon) and gastropods (Goniasma, Trachydomia, Apachella). Nautilid (Metacoceras) and pseudorthocerid (Pseudorthoceras) cephalopods hunted in the water column. Eurypterid fossils of the Artinskian are rare. Campylocephalus and Adelophthalmus lived in fresh waters. Trilobites are also rare. Anisopyge from the order Proetida in known from the Artinskian strata of Nevada and Utah, USA. Cartilagenous fish were the dominant marine animals. Kungurodus, a symmoriiform, and Helicoprion, an eugeneodontiform, lived in the sea that covered the territory of modern Kazakhstan. Some cartilagenous fish like Xenacanthus and Orthacanthus also inhabited rivers and lakes. Several reptiles like Mesosaurus and Brazilosaurus adapted to life in seas and hunted small animals.
Numerous insects including griffinflies (Typus, Meganeuropsis), megasecopterans (Protohymen) and cockroaches lived near freshwater bodies, alongsite with numerous amphibians. Diplocaulus, which had an unusual head, probably adapted to camouflage itself at the bottom of reservoirs, while small Pantylus and larger Trimerorhachis was probably an ambush predator that swallowed large fish. Several amphibians such as Eryops and Seymouria had thick skin, which allowed them to spend more time away from water, which was important in a climate that was becoming drier. However, amniotes were the dominant land vertebrates. Among synapsids, large predators like Ophiacodon and Dimetrodon existed. Sauropsids evolved into different groups. Numerous eureptiles (Opisthodontosaurus, Captorhinus, Labidosauriscus) and parareptiles (Microleter, Delorhynchus, Abyssomedon) are known from this age.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.