See Raetians for the Alpine people of antiquity. See Romansh language for the Rhaetian language.

The Rhaetian is in geochronology

Geochronology

Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

 the latest age of the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 period or in chronostratigraphy

Chronostratigraphy

Chronostratigraphy is the branch of stratigraphy that studies the age of rock strata in relation to time.The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of...

 the uppermost stage of the Triassic system. It lasted from 203.6 ± 1.5 to 199.6 ± 0.6 million years ago. It was preceded by the Norian

Norian

The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...

 and succeeded by the Hettangian

Hettangian

The Hettangian is the earliest age or lowest stage of the Jurassic period of the geologic timescale. It spans the time between 199.6 ± 0.6 Ma and 196.5 ± 1 Ma . The Hettangian follows the Rhaetian and is followed by the Sinemurian.In Europe stratigraphy the Hettangian is a part of the time span in...

 (the lowermost stage or earliest age of the Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

).

In this age, Pangaea

Pangaea

Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....

 began to break up, though the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 was not yet formed.

Stratigraphic definitions

The Rhaetian is named after the Rhaetian Alps

Rhaetian Alps

The Rhaetian Alps are a part of the Central Eastern Alps along the Italian–Swiss and Austrian–Swiss borders, mostly located in the Graubünden canton in eastern Switzerland.Piz Bernina , set on the Italian border, is the highest peak....

, a mountain chain stretching over parts of eastern Switzerland

Switzerland

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

, northern Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 and western Austria

Austria

Austria , 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...

. The stage was introduced in scientific literature by Austrian geologist Eduard Suess

Eduard Suess

Eduard Suess was a geologist who was an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana and the Tethys Ocean.Born in London to a Jewish Saxon merchant, when he was three his family relocated toPrague,...

 and German paleontologist Albert Oppel

Albert Oppel

Carl Albert Oppel was a German paleontologist.-History:He was born at Hohenheim in Württemberg, on December 19, 1831. He first went to the University of Tübingen, where he graduated with a Ph.D. in 1853. The results of his work was published in Die Juraformation Englands, Frankreichs and des...

 in 1856.

The base of the Rhaetian did not yet have a unanimously agreed upon definition in 2009. In the Tethyan domain

Tethys Ocean

The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...

, the base of the ammonite

Ammonite

Ammonite, 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...

 biozone

Biozone

Biostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....

 of Sagenites reticulatus is used, in the boreal domain (where this species is not found) the base of the biozone of Cochloceras amoenum is used instead. The base is also close to the first appearances of conodont

Conodont

Conodonts 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 Misikella spp. and Epigondolella mosheri and radiolarite

Radiolarite

Radiolarite is a siliceous, comparatively hard, fine-grained, chert-like, and homogeneous sedimentary rock that is composed predominantly of the microscopic remains of radiolarians. This term is also used for indurated radiolarian oozes and sometimes as a synonym of radiolarian earth...

 species Proparvicingula moniliformis.

The top of the Rhaetian (the base of the Hettangian stage, the Lower Jurassic series

Series (stratigraphy)

Series 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...

 and the Jurassic system) is at the first appearance of ammonite genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Psiloceras

Psiloceras

Psiloceras is an extinct genus of cephalopod belonging to the ammonite subclass. Psiloceras fossils are commonly found at Lyme Regis, Dorset Coast, England. Here smooth-shelled Psiloceras planorbis are to be found as usually flattened fossils in the Blue Lias....

.

In the Tethyan domain, the Rhaetian contains two ammonite biozones. The highest ammonite biozone is that of Choristoceras marshi, the lower one that of Rhabdoceras suesii.

Dinosauria

Dinosaur Dinosaur Dinosaurs 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... s of the Rhaetian
Taxa	Presence	Location	Description	Images
Agnosphitys Agnosphitys Agnosphitys is a disputed genus of dinosaur. It contains only one species, the type species A. cromhallensis. Its remains include an ilium, maxilla, astragalus and humerus, which date variously from the Norian and Rhaetian stages of the Late Triassic...
Agrosaurus Agrosaurus Agrosaurus is the name given to the remains of what was originally believed to be a Triassic prosauropod from Australia. Agrosaurus would thus be the oldest dinosaur from that country. However, this appears to have been an error, and the material actually appears to come from Thecodontosaurus or...
Liliensternus Liliensternus Liliensternus was a genus of coelophysoid dinosaur from the Late Triassic period, about 205 Ma.Liliensternus was originally named in 1934 by Friedrich von Huene as a second species of Halticosaurus, H. liliensterni, the specific name honouring the German amateur paleontologist, Dr...
Pantydraco Pantydraco Pantydraco was a genus of basal sauropodomorph dinosaur from the Late Triassic of United Kingdom...
Thecodontosaurus Thecodontosaurus Thecodontosaurus is a genus of herbivorous basal sauropodomorph dinosaur which lived during the late Triassic period ....	Norian Norian The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in... /Rhaetian

Mammaliaformes

Mammaliaformes Mammaliaformes Mammaliaformes is a clade that contains the mammals and their closest extinct relatives. Phylogenetically, it is defined as a clade including the most recent common ancestor of Sinoconodon, morganuconodonts, docodonts, Monotremata, Marsupialia, Placentalia, extinct members of this clade, and all...  of the Rhaetian
Taxa	Presence	Location	Description	Images
Eozostrodon Eozostrodon Eozostrodon was one of the earliest mammals. It lived during the late Triassic and the early Jurassic, about 210 million years ago. Eozostrodon was one of the largest early mammals, measuring more than a meter long....
Haramiya Haramiya Haramiya is a mammaliform that is a lineage either unrelated or a paraphyletic parent to multituberculates from the Mesozoic era.Only Haramiyas teeth and skull have been found; judging from these it has been constructed as a 12 cm creature with a resemblance to modern voles...
Megazostrodon Megazostrodon Megazostrodon is an extinct Mammaliaform, widely accepted as being one of the first mammals, appearing in the fossil record approximately 200 million years ago...

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

Cambridge University Press

Cambridge 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

• GeoWhen Database - Rhaetian
• Upper 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, http://norges.uio.no/timescale/Late_Triassic.pdf and http://norges.uio.no/timescale/Fig16.1_Tri_colA.pdf