In the geologic timescale, the
Anisian is the lower stage or earliest age of the
Middle TriassicIn the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
seriesSeries are subdivisions of rock layers made based on the age of the rock and corresponding to the dating system unit called an epoch, both being formally defined international conventions of the geological timescale. A series is therefore a sequence of rock depositions defining a...
or epoch and lasted from 245 million years ago until 237 million years ago, approximately. The Anisian age succeeds the
OlenekianIn the geologic timescale, the Olenekian is an age in the Early Triassic epoch or a stage in the Lower Triassic series. It spans the time between 249.7 ± 0.7 Ma and 245 ± 0.7 Ma . The Olenekian follows the Induan and is followed by the Anisian.The Olenekian saw the deposition of a large part of the...
age (part of the Lower Triassic epoch) and precedes the
LadinianThe Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between 237 ± 2 Ma and 228 ± 2 Ma...
age.
Stratigraphic definitions
The stage and its name were established by
AustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
n geologists
Wilhelm Heinrich WaagenWilhelm Heinrich Waagen was a geologist and paleontologist. He was born June 23, 1841 in Munich and died March 24, 1900 in Vienna.-Overview:He received a Doctor of Philosophy degree at the University of Munich, where he published an elaborate work on geology that was crowned by the university...
and Carl Diener in 1895. The name comes from
Anisus, the
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
name of the river
EnnsEnns may refer to:* Enns , Upper Austria, Austria* Enns , a surname* Enns , a southern tributary of the Danube River...
. The original
type localityType locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
is at Großreifling in the
Austrian stateAustria is a federal republic made up of nine states, known in German as Länder . Since Land is also the German word for a country, the term Bundesländer is often used instead to avoid ambiguity. The Constitution of Austria uses both terms...
of Styria.
The base of the Anisian stage (also the base of the Middel Triassic series) is sometimes laid at the first appearance of
conodontConodonts are extinct chordates resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils now called conodont elements, found in isolation. Knowledge about soft tissues remains relatively sparse to this day...
species
Chiosella timorensis in the stratigraphic record. Other stratigraphers prefer to use the base of magnetic chronozone MT1n. The global reference profile for the base (the GSSP or golden spike) is at a flank of the mountain Deşli Caira in the
RomaniaRomania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
n
DobrujaDobruja is a historical region shared by Bulgaria and Romania, located between the lower Danube river and the Black Sea, including the Danube Delta, Romanian coast and the northernmost part of the Bulgarian coast...
.
The top of the Anisian (the base of the Ladinian) is at the first appearance of
ammoniteAmmonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
species
Eoprotrachyceras curionii and the ammonite
familyIn biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
TrachyceratidaeThe Trachyceratidae is a family of ceratitid ammonoid cephalopods that lived during the Middle- and Late Triassic characterized by shells that are more or less involute and highly ornamented....
. The conodont species
Neogondolella praehungarica appears at the same level.
Sometimes (especially in Central Europe) the Anisian stage is subdivided into four substages: Aegean, Bythinian, Pelsonian and Illyrian.
The Anisian contains six ammonite
biozoneBiostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....
s:
- zone of Nevadites
- zone of Hungarites
- zone of Paraceratites
- zone of Balatonites balatonicus
Balatonites is an extinct cephalopod genus belonging to the ceratitid family Balatonitidae. There are at least four known species: B. balatonicus, B. oyama, B. shoshonensis, and B. zitteli....
- zone of Kocaelia
- zone of Acrochordiceras
Acrochordiceras is a Middle Triassic ammonoid cephalopod belonging to the ceratitid family Acrochordiceratidae, included in the superfamily Ceratitaceae....
Palaeontology
The earliest potential
dinosaurDinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
fossil to date is a partial
pubisIn vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
from Anisian-age rocks of the
Moenkopi FormationThe Moenkopi 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 group in Arizona. Part of the Colorado Plateau and Basin and Range, this formation was...
,
ArizonaArizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. It may have come from a herrerasaurid.
Examples of vertebrates from this age are:
- Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
s
- Prestosuchids
Prestosuchids were a group of Triassic carnivorous archosaurs. They were large active terrestrial apex predators, ranging from around in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time...
- Trigoniids
The Trigoniidae represent a large and morphologically interesting family of highly ornamented non-siphonate bivalves. They originated from the Myophoriidae in the Triassic and underwent an explosion of diversity in the Jurassic, reaching an acme in the Cretaceous, although most genera became...
†Archosauromorphs (non-archosaurians)
| †Non-archosaurian A group of taxa is said to be paraphyletic if the group consists of all the descendants of a hypothetical closest common ancestor minus one or more monophyletic groups of descendants...
Archosauromorphs of the Anisian |
| Taxa |
Presence |
Location |
Description |
Images |
- Erythrosuchus
Erythrosuchus is an extinct genus of archosauriform reptile from the Triassic of South Africa and Namibia. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South Africa as well as the Omingonde Formation in Namibia.Erythrosuchus was the largest...
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†Therapsids (non-mammalian)
| †Non-mammalian A group of taxa is said to be paraphyletic if the group consists of all the descendants of a hypothetical closest common ancestor minus one or more monophyletic groups of descendants...
Therapsids of the Anisian |
| Taxa |
Presence |
Location |
Description |
Images |
- Kannemeyeria
Kannemeyeria was a large dicynodont of the family Kannemeyeriidae, one of the first representatives of the family, and hence one of the first large herbivores of the Triassic...
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†Nothosauroids
| Nothosauroids of the Anisian |
| Taxa |
Presence |
Location |
Description |
Images |
- Anarosaurus
Anarosaurus is an extinct genus of early plesiosaur that lived in the Middle Triassic period ....
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- Ceresiosaurus
Ceresiosaurus, meaning "Lizard of Ceresio" , is an extinct genus of aquatic sauropterygian reptile belonging to the nothosaur order...
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DactylosaurusDactylosaurus is a genus of nothosaur in the family Pachypleurosauridae. Along with Anarosaurus, Dactylosaurus was one of the earliest known pachypleurosaurs to come from Europe.-Etymology:...
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KeichousaurusKeichousaurus is a genus of marine reptile in the pachypleurosaur family which went extinct at the close of the Triassic in the Triassic-Jurassic extinction event. The name derives from Kweichow in China where the first fossil specimen was discovered in 1957...
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Guizhou and Hubei, China |
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†Placodonts
| Placodonts of the Anisian |
| Taxa |
Presence |
Location |
Description |
Images |
- Cyamodus
Cyamodus was a placodont, known from fossil remains discovered in Germany, in the early-to-mid-19th century and was named by Christian Erich Hermann von Meyer, in 1863. The fossils have been dated to the Triassic Period, from the Anisian to Ladinian stages...
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- Paraplacodus
Paraplacodus was a Placodont from the middle Triassic period, during the Anisian to Ladinian stages. The fossils were uncovered in Northern Italy and the species was named in 1931 by Bernhard Peyer. Paraplacodus means "Almost Placodus", and thus far only one species, P...
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Northern Italy |
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†Thalattosaurians
| Thalattosauria of the Anisian |
| Taxa |
Presence |
Location |
Description |
Images |
- Askeptosaurus
Askeptosaurus is an extinct genus of aquatic reptile related to the thalattosaurian group. Their remains have been found in Italy and Switzerland.Askeptosaurus was a very thin, elongated creature, that probably swam like an eel...
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Italy |
A very thin, elongated creature (about 2 meters long) that probably swam like an eel, that was probably a fish eater and hunted in deep waters, based on its large eyes (which would allow it to see better in dark water) and the protective bony ring around them (also seen in ichthyosaurs), which prevented them from getting squashed in by the immense water pressure at great depths. |
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†Ceratitida
AnanoritesAnanorites is an extinct cephalopod belonging to the ceratitd family Noritidae found in the Middle Triassic of the Himalaya. The shell is thinly discoidal, evolute, and smooth; cross section highly compressed; venter narrowly rounded except at the late stage where sharp shoulders are developed.As...
ArthaberitesArthaberites is a ceratitid cephalopod included in the Noritidaethat lived during the Middle Triassic, found in the Alps and Balkans of Europe. Its type is A. alexandrae...
BeyrichitesBeyrichites is an extinct genus in the ammonoid cephalopod, order Ceratitida from the Lower and Middle Triassic of southern Europe, Asia, and western North America....
Bosnites
Buddhaites
Bukowskiites
Caucasites
Danubites
Gangadharites
Japonites
Laboceras
Longobarditoides
Mesocladiscites
Noetlingites
Parapinacoceras
Parasageceras
Phyllocladiscites
Proavites
Pseudodanubites
Psilocladiscites
Salterites
Tropigymnites
XiphogymnitesXiphogymnites is an extinct genus of cephalopod belonging to the Ammonite subclass....
Pararcestes
Sageceras
Lower
AlloptychitesAlloptychites is an extinct genus of cephalopod belonging to the Ammonite subclass....
AnagymnitesAnagymnites is an extinct genus of cephalopod belonging to the Ammonite subclass....
Grambergia
Groenlandites
GymnitesGymnites is a genus of ammonoid cephalopod from the Middle Triassic belonging to the ceratitid family Gymnitidae.-Description:The shell of Gymnites is evolute, generally smooth, with a wide umbilicus. Whorls are moderately embracing, whorl section oval and somewhat compressed. The outer whorl may...
Lenotropites
Pearylandites
Silberlingites
Isculites
Stenopopanoceras
Middle
AcrochordicerasAcrochordiceras is a Middle Triassic ammonoid cephalopod belonging to the ceratitid family Acrochordiceratidae, included in the superfamily Ceratitaceae....
AlanitesAlanites is an extinct Triassic ammonoid cephalopod genus named by Shevyrev, 1968, found in association with Laboceras and Megaphyllites in Siberia and assigned to the ceratitid family Khvlaynitidae which is part of the Dinaritaceae. Its type is Alanites visendus .-References:*...
AnagymnotocerasAnagymnotoceras is an extinct genus of cephalopod belonging to the Ammonite subclass....
ArctohungaritesArctohungarites is a Triassic ammonoid now placed in the ceratitid family Danubitidae, but previously included in the Hungeritidae.The shell of Arctohungerites is subdiscoidal, involute, with a rounded venter, weak sigmoidal folds on the body chamber and a distinct ventral keel on the distal end...
BalatonitesBalatonites is an extinct cephalopod genus belonging to the ceratitid family Balatonitidae. There are at least four known species: B. balatonicus, B. oyama, B. shoshonensis, and B. zitteli....
Bulogites
Cuccoceras
Czekanowskites
Epacrochordiceras
Hollandites
Huishuites
Inaigymnites
Ismidites
Kiparisovia
Malletophychites
Nicomedites
Phillipites
Platycuccoceras
Pronoetlingites
Reiflingites
Discoptychites
Intornites
Nevadisculites
Paraceratites
Parapopanoceras
Proarcestes
Longobardites
Ptychites
Upper
Amphipopanoceras
AplococerasAplococeras is an extinct genus of cephalopod belonging to the Ammonite subclass....
ArctogymnitesArctogymnites is an ammonoid cephalopod from the middle Triassic included in the ceratitid subfamily Beyrichitinae. Related genera include Beyrichites, Frechites, Gymnotoceras, and Salterites...
Eudiscoceras
Eutomoceras
Gymnotoceras
Halilucites
Judicarites
Kellnerites
Metadinarites
Nevadites
Parakellnerites
Proteusites
Repossia
Semiornites
Serpianites
Stoppaniceras
Ticinites
Tozerites
Tropigastrites
Joannites
Epigymnites
CeratitesCeratites is an extinct genus of ammonite cephalopod that lived in marine habitats in what is now Europe, Asia, and North America during the Triassic. It has a ceratitic suture pattern on its shell....
Flexoptychites
FrechitesFrechites is an early Triassic ammonite, a kind of cephalopod with an external shell, included in the ceratitid family Beyrichitidae.-Taxonomic revision:...
Norites
Gevanites
Hungarites
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.;
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 PressCambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by Henry VIII in 1534, it is the world's oldest publishing house, and the second largest university press in the world...
.
External links