Yarenskian Gorizont

Vertebrate index fossils of the Fedorovskian include the lungfish Gnathorhiza, the trematosaurid Inflectosaurus, and the procolophonid Burtensia.

The most fossiliferous and best-exposed is the Petropavlovskaya Svita (anglicized as Petropavlovka Formation), a Fedorovskian-age assemblage in the Cis-Ural region (near the Ural River in Orenburg Oblast).

Another productive unit is the Gamskian-age Lipovskaya Formation, which is found near the Don River in Volgograd Oblast.

The Caspian Depression includes coastal sediments equivalent to the Yarenskian (such as the Bogdo or Bogdinskaya Svita),[2] though there is some controversy over how the stratigraphy of the area should be defined.

[4] Thin exposures of Yarenskian units are also known further north in the Vyatka, Vychegda, Luza, and Pechora basins.