Anisian


In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian age succeeds the Olenekian age and precedes the Ladinian age.

Stratigraphic definitions

The stage and its name were established by Austrian geologists Wilhelm Heinrich Waagen and Carl Diener in 1895. The name comes from Anisus, the Latin name of the river Enns. The original type locality is at Großreifling in the Austrian state of Styria.
The base of the Anisian stage is sometimes laid at the first appearance of conodont 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 is at a flank of the mountain Deşli Caira in the Romanian Dobruja.
The top of the Anisian is at the first appearance of ammonite species Eoprotrachyceras curionii and the ammonite family Trachyceratidae. 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 biozones:

Chondrichthyans

Actinopterygians

†Temnospondyls

†Ichthyopterygians

†Thalattosaurians

†Helveticosaurids

†Saurosphargids

†Sauropterygians

†Pistosaurs

†Pachypleurosaurs

†Nothosaurs

†Placodonts

Archosauromorphs

†Rhynchosaurs

†Tanystropheids

Archosauriforms

Archosaurs

Parareptilia

Therapsids

†Ceratitida

Ananorites
Arthaberites
Beyrichites
Bosnites
Buddhaites
Bukowskiites
Caucasites
Danubites
Gangadharites
Japonites
Laboceras
Longobarditoides
Mesocladiscites
Noetlingites
Parapinacoceras
Parasageceras
Phyllocladiscites
Proavites
Pseudodanubites
Psilocladiscites
Salterites
Tropigymnites
Xiphogymnites
Pararcestes
Sageceras

Lower

Alloptychites
Anagymnites
Grambergia
Groenlandites
Gymnites
Lenotropites
Pearylandites
Silberlingites
Isculites
Stenopopanoceras

Middle

Acrochordiceras
Alanites
Anagymnotoceras
Arctohungarites
Balatonites
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
Aplococeras
Arctogymnites
Eudiscoceras
Eutomoceras
Gymnotoceras
Halilucites
Judicarites
Kellnerites
Metadinarites
Nevadites
Parakellnerites
Proteusites
Repossia
Semiornites
Serpianites
Stoppaniceras
Ticinites
Tozerites
Tropigastrites
Joannites
Epigymnites
Ceratites
Flexoptychites
Frechites
Norites
Gevanites
Hungarites

†Phylloceratida

Spinoleiophyllites
Ussurites
Monophyllites

Nautilida

Trachynautilus
Thuringionautilus
Styrionautilus

Lower

Indonautilus
Sibyllonautilus

Middle

Paranautilus

Upper

Holconautilus
Proclydonautilus

†Aulacocerida

Crassiatractites
Breviatractites

Lower

Mojsisovicsteuthis

Pterioida

Literature