The Erfurt Formation, also known as the Lower Keuper (

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

: ''Untere Keuper'', ''Lettenkeuper'', ''Lettenkohle'' or ''Lettenkohlenkeuper''), is a

stratigraphic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the

Keuper The Keuper is a lithostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of west and central Europe. The Keuper consists of dolomite, shales or claystones and evaporites that were deposited during the Middle and Lat ...

group and the

Germanic Trias The Germanic Trias Supergroup () is a lithostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of western and central Europe (north of the Alps) and the North Sea. Almost all of the Germanic Trias was deposited during ...

supergroup. It was deposited during 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 ...

stage of the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

period.Erfurt Formation
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org It lies above the

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

and below the Middle Keuper.

Definition

The formation was defined in Erfurt-Melchendorf in 1830 by Franz Xaver Hofmann and named for the nearby town of

Erfurt Erfurt () is the capital (political), capital and largest city of the Central Germany (cultural area), Central German state of Thuringia, with a population of around 216,000. It lies in the wide valley of the Gera (river), River Gera, in the so ...

. The Erfurt Formation is underlain by the

. The lower boundary to the Erfurt Formation is the "Lettenkohlensandstein" in northern Germany and the "Grenz-bone-beds" in southern Germany. The formation is a sequence of dolomite, lacustrine

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...

s, and fluviatile

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s. The color is usually grey but can also be brown or reddish brown. The average thickness is 60 to 80 meter, with a maximum thickness of 700 meter in the Glückstadt-Graben. The upper boundary is marked by dolomites, or

s of the Grabfeld Formation.

Fossil content

The Erfurt Formation is known for its vertebrate fossils. Different kinds of fish, amphibians and archosauriforms have been found. Usually they are found as

bone beds A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. ...

, but in 1977 the first complete skeletons were found near

Kupferzell Kupferzell is a small German town in the district of Hohenlohe in Baden-Württemberg, Germany named after the Kupfer river flowing through it. The largest neighbouring towns are Künzelsau (to the north) and Schwäbisch Hall (to the south). Hi ...

. They include ''

Mastodonsaurus ''Mastodonsaurus'' (meaning "teat tooth lizard") is an extinct genus of temnospondyl amphibian from the Middle Triassic of Europe. It belongs to a Triassic group of temnospondyls called Capitosauria, characterized by their large body size, large ...

'', ''

Gerrothorax ''Gerrothorax'' ("wicker chest") is an extinct genus of temnospondyl amphibian from the Triassic period of Greenland, Germany, Poland, Sweden, and possibly Thailand. It is known from a single species, ''G. pulcherrimus'', although several other s ...

'', ''

Plagiosuchus ''Plagiosuchus'' is an extinct genus of plagiosaurid temnospondyl. It is known from several collections from the Middle Triassic of Germany. History of study The type and only species of ''Plagiosuchus, P. pustuliferus'', was originally descr ...

'', ''

Callistomordax ''Callistomordax'' is an extinct genus of temnospondyl amphibian from the Middle Triassic of Germany. The type and only species, ''Callistomordax kugleri'', was named in 2008. It is known from several well-preserved skeletons found in the Erfurt F ...

'', '' Nanogomphodon'', ''

Batrachotomus ''Batrachotomus'' is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. ''Batrachotomus'' was descri ...

'', ''

Kupferzellia ''Tatrasuchus'' is an extinct genus of temnospondyl from the Middle Triassic of Poland and Germany. It is classified as a member of the family Cyclotosauridae or Mastodonsauridae. It is closely related to the genus ''Cyclotosaurus''. The type spe ...

'' and '' Palaeoxyris friessi''.

Reptiles

Synapsids

Amphibians

Bony fish

Cartilaginous fish

References

{{Reflist Triassic System of Europe Triassic Germany Ladinian Stage Marl formations Dolomite formations Limestone formations Shale formations Sandstone formations Shallow marine deposits Ooliferous formations Fossiliferous stratigraphic units of Europe Paleontology in Germany Formations Formations