Gzhelian

Gzhelian
	303.7 ± 0.1 – 298.9 ± 0.15 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
	Key events in the Carboniferous -360 — – -355 — – -350 — – -345 — – -340 — – -335 — – -330 — – -325 — – -320 — – -315 — – -310 — – -305 — – -300 — – P; a; l; e; o; z; o; i; c D C; a; r; b; o; n; i; f; e; r; o; u; s P M; i; s; s; i; s; s; i; p; p; i; a; n P; e; n; n; s; y; l; v; a; n; i; a; n L; D E; a; r; l; y M; i; d; d; l; e L; a; t; e E; a; r; l; y M; i; d L; a; t; e C; S Famennian Tournaisian Viséan Serpuk. Bashkirian Moscovian Kasimovian Gzhelian Asselian ← Carboniferous Rainforest Collapse ← Mazon Creek Fossils ← End of Romer's Gap ← Start of Romer's Gap Key events of the Carboniferous Period; Axis scale: millions of years ago
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Type section	Gzhel horizon, Ghzel, Moscow Oblast, Russia
Lower boundary definition	Not formally defined
Lower boundary definition candidates	FAD of the Conodont Idiognathodus simulator[1]
Lower boundary GSSP candidate section(s)	Southern Ural mountains[1]; Nashui, Luodian County, Guizhou, China;
Upper boundary definition	FAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline
Upper boundary GSSP	Aidaralash, Ural Mountains, Kazakhstan; 50.2458°N 57.8914°E
GSSP ratified	1996[2]

The Gzhelian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from 303.7 to 298.9 Ma.[3] It follows the Kasimovian age/stage and is followed by the Asselian age/stage, the oldest subdivision of the Permian system.

The Gzhelian is more or less coeval with the Stephanian stage of the regional stratigraphy of Europe.

Name and definition

Type locality for the Gzhelian in Gzhel, Russia

The Gzhelian is named after the Russian village of Gzhel (Russian: Гжель), nearby Ramenskoye, not far from Moscow. The name and type locality were defined by Sergei Nikitin (1850–1909) in 1890.

The base of the Gzhelian is at the first appearance of the Fusulinida genera Daixina, Jigulites and Rugosofusulina, or at the first appearance of the conodont Streptognathodus zethus. The top of the stage (the base of the Permian system) is at the first appearance of the conodont Streptognathodus isolatus within the Streptognathus "wabaunsensis" chronocline.[4] Six meters higher in the reference profile, the Fusulinida species Sphaeroschwagerina vulgaris aktjubensis appears.

At the moment (2008), a golden spike for the Gzhelian stage is yet lacking. A candidate is a section along the Ussolka river (a tributary of the Belaya river) at the edge of the hamlet of Krasnoussolsky, about 120 kilometres south-east of Ufa and 60 kilometres north-east of Sterlitamak (in Bashkortostan).[5]

Biozones

The Gzhelian stage is subdivided into five biozones, based on the conodont genus Streptognathodus:

Streptognathodus wabaunsensis and Streptognathodus bellus Zone
Streptognathodus simplex Zone
Streptognathodus virgilicus Zone
Streptognathodus vitali Zone
Streptognathodus simulator Zone

Gzhelian life

Arthropods

Arthropoda of the Gzhelian
Taxa	Presence	Location	Description	Images
Archimylacris		Flénu Formation, Belgium Middle Coal Formation, Pictou Group, Nova Scotia, Canada France Bochum Formation and Saarbrücker Schichten, Germany the Netherlands Middle and Lower Coal Measures, United Kingdom Arkansas, Carbondale Formation, Illinois, Allegheny Formation, Maryland, Pottsville Formation, Pennsylvania, United States		Arthropleura Meganeura Megarachne
Arthropleura		Flénu Formation, Belgium France Saarbrücker Schichten, Germany Foel and Farrington Formations, United Kingdom and northeastern North America	A 2 m (79 in) long millipede
Meganeura	Pennsylvanian	France, England	A dragonfly with wingspans ranging from 65 cm (25.6 in) to over 70 cm (28 in)
Megarachne		Pallero member, Bajo de Véliz Formation, Argentina	A eurypterid

Cartilaginous fishes

Chondrichthyes of the Gzhelian
Taxa	Presence	Location	Description	Images
Sphenacanthus	Carboniferous	Czech Republic	A xenacanthidan elasmobranch	Sphenacanthus Triodus Xenacanthus
Triodus	Carboniferous to Cisuralian	Germany	A xenacanthidan elasmobranch
Xenacanthus	Carboniferous to Cisuralian	Germany; Nebraska, United States	A xenacanthidan elasmobranch

†Temnospondyls

Temnospondyli of the Gzhelian
Taxa	Presence	Location	Description	Images
Astreptorhachis	Late Carboniferous	Jefferson County, Ohio	An early basal dissorophid, similar to Platyhystrix.	Chenoprosopus Dendrerpeton Iberospondylus Onchiodon
Chenoprosopus	Late Carboniferous-Early Permian	Texas, New Mexico; United States	An edopoid amphibian in the family Cochleosauridae. It was likely a terrestrial vermivore with relatively weak bite.
Dendrerpeton		Joggins and Parrsboro Formations, Nova Scotia, Canada
Iberospondylus		Spain	A genus of basal temnospondyl amphibian which lived in a marine environment.
Lafonius		New Mexico	A dvinosaurian temnospondyl within the family Trimerorhachidae
Onchiodon O. langenhani O. manebachensis O. thuringiensis		Thuringia, Germany	A genus of temnospondyl in the family Eryopidae.

†Lepospondyls

Lepospondyli of the Gzhelian
Taxa	Presence	Location	Description	Images
Diplocaulus Diplocaulus salamandroides		Bond Formation, Danville, Illinois		Diplocaulus

Reptiliomorphs

Reptiliomorphs of the Gzhelian
Taxa	Presence	Location	Description	Images
Diasparactus		New Mexico	A diadectomorph	Diasparactus Limnoscelis
Limnoscelis		Colorado, New Mexico, United States	A diadectomorph

Eureptiles

Eureptilia of the Gzhelian
Taxa	Presence	Location	Description	Images
Euconcordia	Virgilian (late Kasimovian to early Gzhelian stage)	Greenwood County, Kansas, USA	The earliest and most basal known captorhinid reptile.	Petrolacosaurus Spinoaequalis
Petrolacosaurus	Pennsylvanian	United States	An araeoscelidian diapsid, the earliest known reptile with two temporal fenestrae.
Spinoaequalis	Stephanian	United States	A basal araeoscelidian diapsid, one of the earliest known reptiles with two temporal fenestrae and the first known reptile to return to the water,.

Synapsids

Synapsids of the Gzhelian
Taxa	Presence	Location	Description	Images
Archaeovenator	Kasimovian-Gzhelian	Calhouns Shale Formation, Kansas, United States	A varanopid	Archaeovenator Bohemiclavulus Datheosaurus Eocasea Edaphosaurus Ianthasaurus Sphenacodon
Bohemiclavulus	Pennsylvanian	Czech Republic	An edaphosaurid
Cryptovenator		Remigiusberg Formation, Saar-Nahe Basin, Germany	A sphenacodontid
Datheosaurus	Kasimovian-Asselian	Ludwikowice Formation, Nowa Ruda, Poland	A caseasaur
Edaphosaurus	Pennsylvanian to Cisuralian	New Mexico, United States	An edaphosaurid
Eocasea	Kasimovian-Gzhelian	Kansas, United States	Eocasea is the oldest and most basal definite caseid.
Ianthasaurus	Pennsylvanian	Kansas, United States	An edaphosaurid
Milosaurus	Pennsylvanian	Mattoon Formation, Illinois	A haptodontiform
Ophiacodon	Kasimovian-Kungurian	Ada Formation, Oklahoma	An ophiacodont
Sphenacodon	Gzhelian-Artinskian	New Mexico; Utah-Arizona border region, both in USA; possibly England	The English specimen known as S?. brittanicus is now generally classified as Sphenacodontidae incertae sedis separate from the other Sphenacodon species so may need reassigning.

References

"Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.
Davydov et al. 1998.
Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. & Snyder, W.S.; 1998: Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes 21(1): pp 11-18, "Archived copy" (PDF). Archived from the original (PDF) on 2007-09-28. Retrieved 2007-09-28.CS1 maint: archived copy as title (link)
Chernykh, V.V.; Chuvashov, B.I.; Davydov, V.I.; Schmitz, M. & Snyder, W.S.; 2006: Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale Geologija 49(2): pp 205–217, "Archived copy" (PDF). Archived from the original (PDF) on 2007-12-14. Retrieved 2007-12-14.CS1 maint: archived copy as title (link)

External links

Carboniferous timescale at the website of the Norwegian network of offshore records of geology and stratigraphy
Gzhelian, GeoWhen Database

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[GSSP_Web-1] "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 23 December 2020.

[FOOTNOTEDavydovGlenisterSpinosaRitter1998-2] Davydov et al. 1998.

[3] Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press

[4] Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. & Snyder, W.S.; 1998: Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System, Episodes 21(1): pp 11-18, "Archived copy" (PDF). Archived from the original (PDF) on 2007-09-28. Retrieved 2007-09-28.CS1 maint: archived copy as title (link)

[5] Chernykh, V.V.; Chuvashov, B.I.; Davydov, V.I.; Schmitz, M. & Snyder, W.S.; 2006: Usolka section (southern Urals, Russia): a potential candidate for GSSP to define the base of the Gzhelian Stage in the global chronostratigraphic scale Geologija 49(2): pp 205–217, "Archived copy" (PDF). Archived from the original (PDF) on 2007-12-14. Retrieved 2007-12-14.CS1 maint: archived copy as title (link)