The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage ( chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...

Stratigraphic definitions

The Norian was named after the Noric Alps in Austria. The stage was introduced into scientific literature by Austrian geologist Edmund Mojsisovics von Mojsvar in 1869. The Norian Stage begins at the base of the

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

biozones of '' Klamathites macrolobatus'' and '' Stikinoceras kerri'', and at the base of the

conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...

biozones of '' Metapolygnathus communisti'' and '' Metapolygnathus primitius''. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed. The top of the Norian (the base of the Rhaetian) is at the first appearance of ammonite species '' Cochloceras amoenum''. The base of the Rheatian is also close to the first appearance of conodont species '' Misikella spp.'' and ''

Epigondolella mosheri ''Epigondolella'' is an extinct genus of conodonts in the family Gondolellidae. Synonyms '' Mazzaella'' is a new genus for ''Epigondolella carnica'' Krystyn (1975). Use in stratigraphy The top of the Norian (or the base of the Rhaetian, i ...

'' and the radiolarid species '' Proparvicingula moniliformis''. In the Tethys domain, the Norian Stage contains six ammonite biozones: *zone of '' Halorites macer'' *zone of '' Himavatites hogarti'' *zone of '' Cyrtopleurites bicrenatus'' *zone of '' Juvavites magnus'' *zone of '' Malayites paulckei'' *zone of '' Guembelites jandianus''

Subages

The Norian is divided into three global subages or substages: * Lacian (lower Norian) * Alaunian (middle Norian) * Sevatian (upper Norian) Many older studies considered the Rhaetian to be the uppermost substage of the Norian, though it has subsequently been raised to its own stage. The Revueltian land-vertebrate

faunachron In paleontology, biochronology is the correlation in time of biological events using fossils. In its strict sense, it refers to the use of assemblages of fossils that are not tied to stratigraphic sections (in contrast to biostratigraphy, where th ...

corresponds to part of the Norian.

References

Notes

Literature

*; 2005: ''The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale'', Episodes 28(4), pp. 233–244. *; 2004: ''A Geologic Time Scale 2004'', Cambridge University Press. *; 2004: ''Mammals from the Age of Dinosaurs'', Columbia University Press. *; 2008: ''Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas'', Doctoral Dissertation, Texas Tech.

External links

GeoWhen Database - NorianUpper Triassic timescale
at the website of the subcommission for stratigraphic information of the ICS *Norges Network of offshore records of geology and stratigraphy: ''Stratigraphic charts for the Triassic''

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{{Geological history, p, m Norian, *02 Geological ages Triassic geochronology