Asselian

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 295 million years ago (Ma). It was preceded by the Gzhelian (the latest or uppermost subdivision in the Carboniferous) and followed by the Sakmarian.[4]

Asselian
298.9 ± 0.15 – 293.52 ± 0.17 Ma
Chronology
Permian Graphical Timeline
-300 —
-295 —
-290 —
-285 —
-280 —
-275 —
-270 —
-265 —
-260 —
-255 —
-250 —
Subdivision of the Permian according to the ICS, as of 2021.[1]
Vertical axis scale: millions of years ago.
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline
Lower boundary GSSPAidaralash, Ural Mountains, Kazakhstan
50°14′45″N 57°53′29″E / 50.2458°N 57.8914°E / 50.2458; 57.8914
GSSP ratified1996[2]
Upper boundary definitionFAD of the Conodont Mesogondolella monstra
Upper boundary GSSPUsolka section, Southern Urals, Russia.
(Coordinates unknown)
GSSP ratified2018[3]

StratigraphyEdit

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.[5]

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.[6] 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 lifeEdit

Cartilaginous fishesEdit

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

Ray-finned fishesEdit

Actinopterygii of the Asselian
Taxa Presence Location Description Images
Carboniferous to Cisuralian Czech Republic
Germany
France
An aeduellid non-neopterygian
Cisuralian Czech Republic An amblypterid non-neopterygian
Cisuralian Czech Republic
France
Cisuralian-Guadalupian Germany
Cisuralian Czech Republic
France
An amblypterid non-neopterygian
Cisuralian Germany

LungfishesEdit

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

†OsteolepiformsEdit

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

†TemnospondylsEdit

Temnospondyli of the Asselian
Taxa Presence Location Description Images
Cisuralian Germany A zatracheidid
Nebraska A genus of dvinosaurian temnospondyl within the family Eobrachyopidae.
Cisuralian Germany A branchiosaurid temnospondyl
Carboniferous to Cisuralian Germany A temnospondyl
Germany; Czech Republic A basal temnospondyl, possibly an archegosauroid.
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.
Cisuralian England A zatracheidid
Southern United States A temnospondyl
Carboniferous to Cisuralian Texas, United States A temnospondyl
Germany A basal temnospondyl, possibly an archegosauroid.
Cisuralian Germany A basal dissorophoidean euskelian temnospondyl.
Czech Republic A species of temnospondyl in the family Eryopidae.
Lauterecken-Odernheim Formation, Germany Palatinerpeton is one of several Late Carboniferous and Early Permian European temnospondyls with uncertain affinities.
Carboniferous to Cisuralian United States A basal dissorophid temnospondyl.
Germany Originally thought as a close relative of the eryopid Onchiodon. It is now often viewed as a basal stereospondylomorph, possibly an archegosauroid.
Abo Formation, New Mexico and Seymour, Baylor County, Texas A temnospondyl
Cisuralian Texas, New Mexico, Oklahoma, United States A zatracheidid

†LepospondylsEdit

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

†SeymouriamorphsEdit

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

†ProcolophonomorphsEdit

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

EureptiliansEdit

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

SynapsidsEdit

Synapsids of the Asselian
Taxa Presence Location Description Images
Cisuralian Germany A varanopid
Les Télots, Margennem, Autun, France
locality 3, Cutler Formation, San Miguel County, Colorado, USA
Kasimovian-Asselian Ludwikowice Formation, Nowa Ruda, Poland
Pennsylvanian to Cisuralian United States An edaphosaurid, one of the oldest herbivorous amniotes
Cisuralian New Mexico, United States An edaphosaurid
Les Télots, Autun, France
A basal sphenacodont.
earliest Asselian Kenilworth, Kenilworth Sandstone Formation, Warwickshire Group, Warwickshire, England A basal sphenacodont, formerly placed in Haptodus as "Haptodus grandis".
Cisuralian Texas, United States An edaphosaurid
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
Königin-Carola-Schacht locality, Dresden, Döhlen Formation, lower Rotliegend Group, Döhlen Basin, Saxony, Germany
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.
Cisuralian An ophiacodontid

ReferencesEdit

  1. ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  2. ^ Davydov, Vladimir; Glenister, Brian; Spinosa, Claude; Ritter, Scott; Chernykh, V.; Wardlaw, B.; Snyder, W. (March 1998). "Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System" (PDF). Episodes. 21: 11–18. doi:10.18814/epiiugs/1998/v21i1/003. Retrieved 7 December 2020.
  3. ^ Shen, Shuzhong (August 2018). "Notes from the SPS Chair" (PDF). Permophile: 4. ISSN 1684-5927. Retrieved 12 December 2020.
  4. ^ Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press
  5. ^ 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
  6. ^ 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 linksEdit

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