| System (period) | Series (epoch) | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Jurassic | Lower | Hettangian | 201.4±0.2 | |
| Triassic | Upper (Late) | Rhaetian | ~208.5 | |
| Norian | ~227 | |||
| Carnian |  ~237
| |||
| Middle | Ladinian | ~242
| ||
| Anisian | 247.2 | |||
| Lower (Early) | Olenekian | 251.2 | ||
| Induan | 251.902±0.024
| |||
| Permian | Lopingian | Changhsingian | older | |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
Cast of a tridactyl footprint of a theropod dinosaur from the Norian of the Czech Republic.
The Norian is a stage of the Upper Triassic series, corresponding to the Norian age of the Late Triassic epoch. It lasted from ~227 to 208.5 million years ago (IUGS 2023). It was preceded by the Carnian and succeeded by the Rhaetian. With a duration of around 18.5 million years, Norian is the longest age of the entire Phanerozoic eon, and it is only slightly shorter than the Neogene period of the Cenozoic.
Definition[]
As of 2024, there is still no GSSP for this stage. The candidates are Black Bear Ridge in Canada and Pizzo Mondello on Sicily, Italy. The First Appearing Datum (FAD) of ammonite, conodont or bivalve species are suggested as the markers of the lower boundary of this stage.[2]
Norian life[]
The seas were inhabited by various cephalopods, of which ammonites (Mesodistichites, Stenarcestes, Noridiscites) and nautilids (Nautilus, Pleuronautilus, Syringoceras) predominated. Shonisaurus, a huge ichthyosaur, lived in the open ocean.
Fish of the orders Semionotiformes (Semionotus) and Palaeonisciformes (Turseodus, Cionichthys, Lasalichthys, Synorichthys) were numerous in Norian rivers and lakes. They were hunted by temnospondyl metoposaurid amphibians like Apachesaurus and phytosaurs such as Rutiodon. Among some groups of reptiles, specialized species appeared. Hypuronector had a wide, flat tail, with which it probably swam well, although there is a version that it lived in trees, like chameleons. Tanytrachelos, a tanystropheid, had an elongated neck with the help of which it apparently caught small animals swimming by. Icarosaurus could hover using leathery membranes attached to its elongated ribs, like modern flying dragons (Draco). The early turtles Proterochersis, Chinlechelys and Proganochelys are known from the fluvial and lacustrine Norian strata.
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.