[1] The formation for example crops out in the Kopet Dag mountain range in the border region of Turkmenistan and Iran.

[2] Previously, it was thought that the earliest horizons of this formation dated to the latest Paleocene (Thanetian).

The fish are found in a 9 metres (30 ft) thick clay horizon in the middle of the succession, that has been dated as earliest Ypresian, around 56 million years ago.

[4] The fauna is largely dominated by three species: Primisardinella genetrix, Chanos torosus, and Mene triangulum.

Uniquely, a high diversity of luvarid fishes is known from the formation, despite this family being represented by a single, very rare species (the louvar) in the modern day.