Viséan

The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from 346.7 to 330.9 Ma.[2] It follows the Tournaisian age/stage and is followed by the Serpukhovian age/stage.

System	Subsystem/ Series	Stage	Age (Ma)
Permian	Cisuralian	Asselian	younger
Carboniferous	Pennsylvanian	Gzhelian	298.9	303.7
		Kasimovian	303.7	307.0
		Moscovian	307.0	315.2
		Bashkirian	315.2	323.2
	Mississippian	Serpukhovian	323.2	330.9
		Visean	330.9	346.7
		Tournaisian	346.7	358.9
Devonian	Late	Famennian	older
Subdivision of the Carboniferous system according to the ICS, as of 2017.[1]

Name and definitions

The Viséan stage was introduced by Belgian geologist André Dumont in 1832. Dumont named this stage after the city of Visé in the Belgian province of Liège. Before being used as an international stage, the Visean stage was part of the (West) European regional geologic time scale, in which it followed the Tournaisian stage and is followed by the Namurian stage. In the North American regional scale, the Visean stage correlates with the upper Osagean, the Meramecian and lower Chesterian stages. In the Chinese regional time scale, it correlates with the lower and middle Tatangian series.[3]

The base of the Viséan stage is at the first appearance of the fusulinid species Eoparastaffella simplex (morphotype 1/morphotype 2). The type locality for the stage base used to be in a road section below the castle of Dinant in Belgium, but this type locality proved to be insufficient for the purpose of stratigraphic correlation.[3] A GSSP has been proposed in the Luzhai Formation near Penchong in the Chinese province of Guanxi.[4] The top (the base of the Serpukhovian and Namurian) is laid at the first appearance of the conodont Lochriea ziegleri,[5] or at the base of the biozone of goniatite Cravenoceras leion.

Tetrapods

One of the tetrapods that lived during the Visean age was Westlothiana, a reptile-like amphibian.

Biostratigraphy

The Visean contains four conodont biozones:

• Lochriea nodosa Zone
• Lochriea mononodosa Zone
• Gnathodus bilineatus Zone
• Gnathodus texanus Zone

In British stratigraphy, the Visean is subdivided into five substages. These are from bottom to top: Chadian (the lower part of this substage falls in the Tournaisian), Arundian, Holkerian, Asbian and Brigantian.[6]

Viséan life

Vertebrates

Cartilaginous fish

Cartilaginous fish of the Viséan
Taxa	Presence	Location	Description	Images
Stethacanthus

Tetrapodomorphs

Tetrapodomorphs of the Viséan
Taxa	Presence	Location	Description	Images
Crassigyrinus	Viséan - Serpukhovian	Scotland	Crassigyrinus had a streamlined body, up to 2 meters in length, with tiny and virtually useless limbs, implying that the animal was almost completely aquatic.
Deltaherpeton	Asbian	Iowa	A colosteid
Eucritta		Scotland	A baphetoid
Greererpeton	late Viséan	North America	A colosteid
Ossinodus	Middle Visean	Queensland, Australia	Possibly a basal whatcheeriid, Ossinodus is one of the first large tetrapods discovered to have existed during Romer's gap and the oldest tetrapod fossil with a preserved injury.
Pholidogaster	Brigantian	Scotland	A colosteid
Sigournea	Asbian	Iowa	A stem-tetrapod known from a single lower jaw, a close relative of Occidens portlocki and possibly a baphetoid.
Spathicephalus S. marsdeni	Asbian	Scotland	A species of baphetoid stem-tetrapod
Whatcheeria	Asbian	Iowa	A whatcheeriid

Temnospondyli

Temnospondyls of the Viséan
Taxa	Presence	Location	Description	Images
Balanerpeton		Scotland	A genus of temnospondyl amphibian

Reptiliomorphs

Reptiliomorphs of the Viséan
Taxa	Presence	Location	Description	Images
Casineria	Asbian	Cheese Bay, Scotland	The earliest known amniote, also likely to be among the first amniotes in the biological sense
Eldeceeon	Brigantian	East Kirkton Quarry, West Lothian, Scotland,	Eldeceeon is thought to be closely related to embolomeres, but it has several distinguishing features
Silvanerpeton	Brigantian	East Kirkton Quarry, West Lothian, Scotland,	It's believed to have been an advanced reptile-like amphibian, close to the origin of amniotes.
Westlothiana	Brigantian	East Kirkton Quarry, West Lothian, Scotland,	Its phylogenetic placement has varied from basal amniote, to a basal lepospondyl, therefore, Westlothiana may actually be closer to modern amphibians than to amniotes, although still close to both.

Arthropods

Arthropods of the Viséan
Taxa	Presence	Location	Description	Images
Arthropleura		Scotland	Tracks
Pulmonoscorpius		East Kirkton Limestone Formation, Scotland

References

1. http://www.stratigraphy.org/index.php/ics-chart-timescale
2. "International Chronostratigraphic Chart". International Commission on Stratigraphy. Retrieved 9 December 2012.
3. Menning, M.; Alekseev, A.S.; Chuvashov, B.I.; Davydov, V.I.; Devuyst, F.-X.; Forke, H.C.; Grunt, T.A.; Hance, L.; Heckel, P.H.; Izokh, N.G.; Jin, Y.-G.; Jones, P.J.; Kotlyar, G.V.; Kozur, H.W.; Nemyrovska, T.I.; Schneider, J.W.; Wang, X.-D.; Weddige, K.; Weyer, D. & Work, D.M.; 2006: Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian–Carboniferous–Permian Correlation Chart 2003 (DCP 2003), Palaeogeography, Palaeoclimatology, Palaeoecology 240(1-2): pp 318–372.
4. Devuyst, F.X.; Hance, L.; Hou, H.-F.; Wu, X.; Tian, S.; Coen, M. & Sevastopulo, G.; 2003: A proposed Global Stratotype Section and Point for the base of the Visean Stage (Carboniferous): the Pengchong section, Guangxi, South China, Episodes 26(2), pp 105–115.
5. Nemyrovska, T.I.; 2005: Late Visean/early Serpukhovian conodont succession from the Triollo section, Palencia (Cantabrian Mountains, Spain), Scr. Geol. 129, pp 13–89.
6. Heckel, P.H. & Clayton, G.; 2006: The Carboniferous system, use of the new official names for the subsystems, series and stages, Geologica Acta 4(3), pp 403–407.

Further reading

• Dumont, A.H.; 1832: Mémoire sur la constitution géologique de la province de Liège, Mémoires couronnés par l'Académie Royale des Sciences et Belles-Lettres de Bruxelles 8(3), VII. (in French)

External links

• Upper and lower time scales for the Carboniferous at the website of the Norwegian network of offshore records of geology and stratigraphy.
• Visean, Geowhen Database
• The Viséan age, www.palaeos.com