In the geologic timescale, the Middle Triassic is the second of three epoch

Epoch (geology)

An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

s 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 the middle of three 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...

 in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma (million years ago). The Middle Triassic is divided into the Anisian

Anisian

In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from 245 million years ago until 237 million years ago, approximately...

 and Ladinian

Ladinian

The 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...

 ages or stages.

Formerly the middle series in the Triassic was also known as Muschelkalk

Muschelkalk

The Muschelkalk is a sequence of sedimentary rock strata in the geology of central and western Europe. It has a Middle Triassic age and forms the middle part of the Germanic Trias, that further consists of the Buntsandstein and Keuper...

. This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe.