In the

geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochron ...

, the Anisian is the lower

stage Stage, stages, or staging may refer to: Arts and media Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly Brit ...

or earliest

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

of the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...

series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used i ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

and lasted from million years ago until million years ago. The Anisian Age succeeds the

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

Age (part of the

Lower Triassic The Early Triassic is the first of three epoch (geology), epochs of the Triassic Period (geology), Period of the geologic timescale. It spans the time between 251.9 annum, Ma and Ma (million years ago). Rocks from this epoch are collectively kno ...

Epoch) and precedes the

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic ...

Age.

Stratigraphic definitions

The stage and its name were established by

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

n geologists

Wilhelm Heinrich Waagen Wilhelm Heinrich Waagen (23 June 184124 March 1900) was a German geologist and paleontologist. He was born in Munich and died in Vienna. He worked from 1870 to 1875 in the Geological Survey of India. He was a professor of paleontology at the Univ ...

and

Carl Diener Carl Diener (11 December 1862 – 6 January 1928) was an Austrian geographer, geologist and paleontologist. Biography In 1883 he received his doctorate from the University of Vienna, where his instructors included Eduard Suess and Melchior ...

in 1895. The name comes from ''Anisus'', the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

name of the river Enns. The original type locality is at Großreifling in the Austrian state of

Styria Styria ( ; ; ; ) is an Austrian Federal states of Austria, state in the southeast of the country. With an area of approximately , Styria is Austria's second largest state, after Lower Austria. It is bordered to the south by Slovenia, and cloc ...

. The base of the Anisian Stage (also the base of the Middle Triassic series) is sometimes laid at the first appearance of

conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

species '' Chiosella timorensis'' in the stratigraphic record. Other stratigraphers prefer to use the base of

magnetic chronozone Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...

MT1n. There is no accepted global reference profile for the base, but one ( GSSP or golden spike) was proposed at a flank of the mountain Deșli Caira in the

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

Dobruja Dobruja or Dobrudja (; or ''Dobrudža''; , or ; ; Dobrujan Tatar: ''Tomrîğa''; Ukrainian language, Ukrainian and ) is a Geography, geographical and historical region in Southeastern Europe that has been divided since the 19th century betw ...

.The GSSP was proposed by Grădinaru ''et al.'' (2007) The top of the Anisian (the base of the Ladinian) is at the first appearance of

ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

species '' Eoprotrachyceras curionii'' and the ammonite

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Trachyceratidae The Trachyceratidae is an extinct family of ceratitid Ammonoidea, ammonoid cephalopods. The Trachyceratidae makes up part of the superfamily Trachyceratoidea along with such families as the Buchitidae, Distichitidae, Dronovitidae and Noridisci ...

. The conodont species '' Neogondolella praehungarica'' appears at the same level. Especially in Central Europe the Anisian Stage is sometimes subdivided into four substages: Aegean, Bythinian, Pelsonian and Illyrian. The Anisian contains six ammonite

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxon, taxa, as opposed to a Lithostratigraphy, lithostratigraphic unit which is defined by the ...

s: *zone of '' Nevadites'' *zone of '' Hungarites'' *zone of '' Paraceratites'' *zone of '' Balatonites balatonicus'' *zone of '' Kocaelia'' *zone of '' Acrochordiceras''

Selected formations

* Ashfield Shale (

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

, Australia) * Lower and middle

Besano Formation The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a thin but fossiliferous succession of Dolomite (rock), dolomite and Shale, black shale, is famous for its preserva ...

(Switzerland and Italy) * Upper

Ermaying Formation The Ermaying Formation is a geological formation of Anisian (Middle Triassic) age in north-central China. It is found across much of the Ordos Basin, at outcrops within the provinces of Shaanxi, Shanxi, and Inner Mongolia. It is composed of up to ...

(

Shaanxi Shaanxi is a Provinces of China, province in north Northwestern China. It borders the province-level divisions of Inner Mongolia to the north; Shanxi and Henan to the east; Hubei, Chongqing, and Sichuan to the south; and Gansu and Ningxia to t ...

and

Shanxi Shanxi; Chinese postal romanization, formerly romanised as Shansi is a Provinces of China, province in North China. Its capital and largest city of the province is Taiyuan, while its next most populated prefecture-level cities are Changzhi a ...

, China) * Favret Formation / Prida Formation ( Fossil Hill Member) (Nevada, US) * Grès à Voltzia (France) *

Guanling Formation The Guanling Formation is a Middle Triassic (Anisian or Pelsonian in the regional chronostratigraphy) geologic Formation (geology), formation in southwestern China. Geology The formation encompasses two members. The first member is primarily c ...

(

Guizhou ) , image_skyline = , image_caption = , image_map = Guizhou in China (+all claims hatched).svg , mapsize = 275px , map_alt = Map showing the location of Guizhou Province , map_caption = Map s ...

and

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

, China) *

Moenkopi Formation The Moenkopi Formation is a geological formation that is spread across the U.S. states of New Mexico, northern Arizona, Nevada, southeastern California, eastern Utah and western Colorado. This unit is considered to be a Geological unit, group ...

(Holbrook and Anton Chico members) (SW US) * Lower and Middle

Muschelkalk The Muschelkalk (German for "shell-bearing limestone"; ) is a sequence of sedimentary rock, sedimentary rock strata (a lithostratigraphy, lithostratigraphic unit) in the geology of central and western Europe. It has a Middle Triassic (240 to 230 m ...

(central Europe) * Röt Formation / Upper Buntsandstein (Germany)

References

Sources

*; 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. *; 2007: ''The Global Boundary Stratotype Section and Point (GSSP) for the base of the Anisian Stage: Deşli Caira Hill, North Dobrogea, Romania'', Albertiana 36, pp. 54–71. *; 2004: ''A Geologic Time Scale 2004'',

Cambridge University Press Cambridge University Press was the university press of the University of Cambridge. Granted a letters patent by King Henry VIII in 1534, it was the oldest university press in the world. Cambridge University Press merged with Cambridge Assessme ...

External links

GeoWhen Database - AnisianLower Triassic timescale
at the website of the subcommission for stratigraphic information of the ICS
Lower Triassic timescale
at the website of Norges Network of offshore records of geology and stratigraphy. {{coord, 45.0742, N, 28.8022, E, source:wikidata, display=title *01 Geological ages Triassic geochronology