| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Permian | Cisuralian | Asselian | 298.9±0.15 | |
| Carboniferous | Pennsylvanian | Upper | Gzhelian | 303.7±0.1 |
| Kasimovian | 307.0±0.1 | |||
| Middle | Moscovian | 315.2±0.2 | ||
| Lower | Bashkirian |  323.2±0.4
| ||
| Mississippian | Upper | Serpukhovian | 330.9±0.2 | |
| Middle | Visean | 346.7±0.4
| ||
| Lower | Tournaisian | 358.9±0.4
| ||
| Devonian | Upper | Famennian | older | |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Mississippian is a geologic subperiod and subsystem that extends from the end of the Famennian age of the Late Devonian, at 358.9 ± 0.4 million years ago, to the beginning of the Bashkirian age of the Pennsylvanian 323.2 ± 0.4 million years ago. Originally used in North American stratigraphy, it was included in the International chronostratigraphic chart in 1990's. The name Mississippian was given after the Mississippi River, US, in 1869 by Winchell N. G.
In East Europe, the Lower Carboniferous series is used instead of Mississippian, and it corresponds to the Early Carboniferous epoch.
Definition[]
The Global Stratotype Section and Point (GSSP) of the Mississippian subsystem, the Tournaisian stage and the whole Carboniferous system was accepted in 1990. The first appearance of the conodont Siphonodella sulcata was chosen as the marker of the lower boundary of the Mississippian subsystem. The type section is located in La Serre commune in southern France. In 2006 it was discovered that the correlation of the type section is problematic.[2]
Subdivisions[]
Mississippian includes Tournaisian, Visean and Serpukhovian stages. In geochronology, all of them correspond to the same ages.
Climate[]
Ice masses grew at the south pole, causing the climate south of the equator to become colder. Cooling sea temperatures were likely one of the reasons why reef formation at this time did not reach pre-extinction levels. Despite this, low latitudes maintained high temperatures, which made possible the appearance of vast swampy forests.
Flora[]
During this period, the terrestrial flora became increasingly lush. Giant horsetails, tree ferns and conifers (Cordaites) appeared.
Fauna[]
After the Devonian extinctions, coral diversity declined. The formation of massive reefs, comparable to previous epochs, resumed only in the Mesozoic. The number of trilobites also decreased. The trilobite Phillipsia tuberculata is known from the Mississippian deposits of Arizona.
Echinoderms have reached great diversity, including long-stemmed crinoids and starfish. Ramulocrinus is an echinoderm from the Mississippian of North America. From the Mississippian until the end of the Paleozoic, cartilaginous fish became the dominant marine predators. The shark Sphenacanthus is known from the Mississippian strata of the UK.
Kirchnerala treintamil, an early winged insect
On land, active evolution of arthropods took place. The wet, swampy forests were inhabited by a variety of centipedes and arachnids. Pulmonoscorpius, one of the largest scorpions of all time, existed during this time. At the end of the Mississippian, winged insects appeared, which became the first animals capable to fly. Oldest winged insects include Kirchnerala, Argentinala and Delitzschala from the Serpukhovian age.
Romer's gap[]
For a long time, Mississippian sediments exhibited a lack of fossils of semi-aquatic and terrestrial vertebrates, known as the Romer's gap. After the extinction of Devonian tetrapodomorphs like Ichthyostega and Tulerpeton, their descendants existed for about 15 million years but were not represented in the geological record and formed several ghost lineages until the 21st century, when some of these taxa were discovered. Crassigyrinus is known from the Mississippian of the United Kingdom and USA. Pederpes was described in 2002 from the Ballagan Formation in Scotland.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era" (in en). https://timescalefoundation.org/gssp/index.php?parentid=77.