Asselian

Template:Permian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian epoch or series. The Asselian lasted between 298.9 and 293.52 million years ago (Ma). It was preceded by the Gzhelian (the latest or uppermost subdivision in the Carboniferous) and followed by the Sakmarian.^[1]

Stratigraphy

The Asselian stage was introduced into scientific literature in 1954, when the Russian stratigrapher V.E. Ruzhenchev split it from the Artinskian. At that moment the Artinskian still encompassed most of the lower Permian - its current definitions are more restricted. The Asselian is named after the Assel River in the southern Ural Mountains of Kazakhstan and Bashkortostan.^[2]

The base of the Asselian stage is at the same time the base of the Cisuralian series and the Permian system. It is defined as the place in the stratigraphic record where fossils of the conodont Streptognathodus isolatus first appear. The global reference profile for the base (the GSSP or golden spike) is located in the valley of the Aidaralash River, near Aqtöbe in the Ural Mountains of Kazakhstan.^[3] The top of the Asselian stage (the base of the Sakmarian stage) is at the first appearance of conodont species Streptognathodus postfusus.

The Asselian contains five conodont biozones:

zone of Streptognathodus barskovi
zone of Streptognathodus postfusus
zone of Streptognathodus fusus
zone of Streptognathodus constrictus
zone of Streptognathodus isolatus

Asselian life

Cartilaginous fishes

Chondrichthyes of the Asselian
Taxa	Presence	Location	Description	Images
Acanthodes	Carboniferous to Cisuralian	Germany	An acanthodian	Acanthodes Orthacanthus Triodus Xenacanthus
Orthacanthus	Carboniferous to Cisuralian	Germany	A xenacanthidan elasmobranch
Petalodus	Carboniferous to Cisuralian	Russia, United States	A petalodontiform holocephalian
Plicatodus	Carboniferous to Cisuralian	Germany	A xenacanthidan elasmobranch
Triodus	Carboniferous to Cisuralian	Germany	A xenacanthidan elasmobranch
Xenacanthus	Carboniferous to Cisuralian	Germany	A xenacanthidan elasmobranch

Ray-finned fishes

Actinopterygii of the Asselian
Taxa	Presence	Location	Description	Images
Aeduella	Carboniferous to Cisuralian	Czech Republic Germany France	An aeduellid non-neopterygian	Amblypterus Aeduella
Amblypterus	Cisuralian	Czech Republic	An amblypterid non-neopterygian
Igornella	Cisuralian	Czech Republic France
Paramblypterus	Cisuralian	Czech Republic France	An amblypterid non-neopterygian
Westollia	Cisuralian	Germany

Lungfishes

Dipnoi of the Asselian
Taxa	Presence	Location	Description	Images
Conchopoma	Carboniferous to Cisuralian	North America
Ctenodus	Carboniferous to Cisuralian	Czechia
Megapleuron	Carboniferous to Cisuralian	France

†Osteolepiforms

Osteolepiformes of the Asselian
Taxa	Presence	Location	Description	Images
Ectosteorhachis	Cisuralian	North America	A megalichthyid tetrapodomorph	Ectosteorhachis
Palatinichthys	Cisuralian	Germany	A megalichthyid tetrapodomorph

†Temnospondyls

Temnospondyli of the Asselian
Taxa	Presence	Location	Description	Images
Acanthostomatops	Cisuralian	Germany	A zatracheidid	Acanthostomatops Archegosaurus Cheliderpeton Dasyceps Edops Eryops Platyhystrix Sclerocephalus haeuseri Trimerorhachis Zatrachys
Acroplous		Nebraska	A genus of dvinosaurian temnospondyl within the family Eobrachyopidae.
Apateon	Cisuralian	Germany	A branchiosaurid temnospondyl
Archegosaurus	Carboniferous to Cisuralian	Germany	A temnospondyl
Cheliderpeton		Germany; Czech Republic	A basal temnospondyl, possibly an archegosauroid.
Dasyceps	Cisuralian	England	A zatracheidid
Edops	Carboniferous to Viséan	Southern United States	A temnospondyl
Eryops	Carboniferous to Cisuralian	Texas, United States	A temnospondyl
Glanochthon		Germany	A basal temnospondyl, possibly an archegosauroid.
Micromelerpeton	Cisuralian	Germany	A basal dissorophoidean euskelian temnospondyl.
Onchiodon O. credneri		Czech Republic	A species of temnospondyl in the family Eryopidae.
Palatinerpeton		Lauterecken-Odernheim Formation, Germany	Palatinerpeton is one of several Late Carboniferous and Early Permian European temnospondyls with uncertain affinities.
Platyhystrix	Carboniferous to Cisuralian	United States	A temnospondyl
Sclerocephalus S. haeuseri S. bavaricus S. nobilis ?S. jogischneideri		Germany	Originally thought as a close relative of the eryopid Onchiodon. It is now often viewed as a basal stereospondylomorph, possibly an archegosauroid.
Trimerorhachis		Abo Formation, New Mexico and Seymour, Baylor County, Texas	A temnospondyl
Zatrachys	Cisuralian	Texas, New Mexico, Oklahoma, United States	A zatracheidid

†Lepospondyls

Lepospondyli of the Asselian
Taxa	Presence	Location	Description	Images
Batropetes	Cisuralian	Germany	A brachystelechid amphibian	Batropetes Oestocephalus
Oestocephalus	Carboniferous to Cisuralian	Germany	An aïstopod amphibian

†Seymouriamorphs

Seymouriamorpha of the Asselian
Taxa	Presence	Location	Description	Images
Discosauriscus		Boskovice Furrow, Czech Republic	A reptiliomorph	Discosauriscus

†Procolophonomorphs

Procolophonomorpha of the Asselian
Taxa	Presence	Location	Description	Images
Belebey	Cisuralian	Europe	A genus of lizard-shaped parareptile	Belebey

Eureptilians

Eureptilia of the Asselian
Taxa	Presence	Location	Description	Images
Protorothyris	Cisuralian	Texas, West Virginia, USA	A romeriid reptile	Protorothyris
Rhiodenticulatus	Cisuralian	New Mexico, USA	A captorhinid reptile
Romeria	Cisuralian	Texas, USA	A captorhinid reptile

Synapsids

Synapsids of the Asselian
Taxa	Presence	Location	Description	Images
Cabarzia	Cisuralian	Germany	A varanopid	Callibrachion Cutleria Edaphosaurus Gordodon Sphenacodon Stereophallodon
Callibrachion		Les Télots, Margennem, Autun, France
Cutleria		locality 3, Cutler Formation, San Miguel County, Colorado, USA
Datheosaurus	Kasimovian-Asselian	Ludwikowice Formation, Nowa Ruda, Poland
Edaphosaurus	Pennsylvanian to Cisuralian	United States	An edaphosaurid, one of the oldest herbivorous amniotes
Gordodon	Cisuralian	New Mexico, United States	An edaphosaurid
Haptodus Haptodus baylei Haptodus grandis		H. baylei: Les Télots, Autun, France H. grandis: Kenilworth, Kenilworth Sandstone Formation, Warwickshire Group, Warwickshire, England	Haptodus grandis may require its own genus.
Ophiacodon	Kasimovian-Kungurian	Kenilworth, Kenilworth Sandstone Formation, Warwickshire Group, Warwickshire, England Autun, France Cutler Formation, Arizona, Colorado, New Mexico and Utah; Fort riley, Chase Group, Kansas, Green Formation, Dunkard Group, Ohio; Wellington Formation, Oklahoma; Clyde Formation, Texas and Oklahoma; Admiral Formation; Belle-Plains Formation; Wichita Group, all three in Texas
Pantelosaurus		Königin-Carola-Schacht locality, Dresden , Döhlen Formation, lower Rotliegend Group, Döhlen Basin, Saxony, Germany
Sphenacodon	Gzhelian-Artinskian	New Mexico; Utah-Arizona border region; 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.
Stereophallodon	Cisuralian		An ophiacodontid

References

^ Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
^ The Nonmarine Permian: Volume 30 of Bulletin of the New Mexico Museum of Natural History and Science, page 48. Editors Spencer G. Lucas, Kate E. Zeigler, 2005
^ Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. and 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.

External links

GeoWhen Database - Asselian
Upper Paleozoic stratigraphic chart at the website of the subcommission for stratigraphic information of the ICS

50°14′45″N 57°53′29″E / 50.2458°N 57.8914°E / 50.2458; 57.8914

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

[2] The Nonmarine Permian: Volume 30 of Bulletin of the New Mexico Museum of Natural History and Science, page 48. Editors Spencer G. Lucas, Kate E. Zeigler, 2005

[3] Davydov, V.I.; Glenister, B.F.; Spinosa, C.; Ritter, S.M.; Chernykh, V.V.; Wardlaw, B.R. and 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.

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