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Template:Triassic
The Norian is a division of the Triassic geological period . It has the rank of an age (geochronology ) or stage (chronostratigraphy ). The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago .[1] Carnian and succeeded by the Rhaetian .[2]
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 biozones of Klamathites macrolobatus Stikinoceras kerri conodont biozones of Metapolygnathus communisti Metapolygnathus primitius 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 Misikella spp. Epigondolella mosheri radiolarid species Proparvicingula moniliformis
In the Tethys domain , the Norian stage contains six ammonite biozones:
Palaeontology Dinosaurs †Pterosaurs Crocodylomorphs †Ichthyosaurs †Dinosauromorphs (non-dinosaurian) †Placodonts †Crurotarsans (non-crocodylomorph) Mammaliaformes
Mammaliaformes of the Carnian
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†Ammonites References Notes
^ According to Gradstein et al. (2004). Brack et al. (2005) give 226 to 207 million years
^ See for a detailed geologic timescale Gradstein et al. (2004)
Literature Brack, P.; Rieber, H.; Nicora, A. & Mundil, R. ; 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.Gradstein, F.M.; Ogg, J.G. & Smith, A.G. ; 2004 : A Geologic Time Scale 2004 , Cambridge University Press .Martz, J.W. ; 2008 : Lithostratigraphy, chemostratigraphy, and vertebrate biostratigraphy of the Dockum Group (Upper Triassic), of southern Garza County, West Texas , Doctoral Dissertation, Texas Tech.External links
