Rybinskian Gorizont Explained

The Rybinskian Gorizont ("Rybinskian Horizon") is a Lower Triassic biostratigraphic unit in Western Russia. It is a part of the Vetlugian Supergorizont and corresponds to the earliest part of the Olenekian stage, lying above the late Induan-age Zaplavnian Horizon^[1] and below the Sludkian Gorizont. The Rybinskian Gorizont is sometimes known as the Benthosuchus fauna, due to abundant fossils of Benthosuchus, a temnospondyl amphibian index fossil. Related amphibians such as Thoosuchus also increase in abundance, and the interval additionally hosts the oldest fossils of procolophonines and putative true archosaurs in the region.^{[2] [3]}

The Rybinskian is exposed in several svitas (equivalent to geological formations) spread out over a wide area: the type assemblage is the Rybinskaya Svita in the Moscow Syncline, and another is the Staritskya Svita in the Southern Urals area.^[4]

Notes and References

1. Novikov . I. V. . 2018-12-01 . New Stage of Recovery of East European Tetrapod Community after Permian–Triassic Crisis . Paleontological Journal . en . 52 . 7 . 791–795 . 10.1134/S0031030118070080 . 1555-6174.
2. Book: Shishkin . M.A. . The Age of Dinosaurs in Russia and Mongolia . Ochev . V.G. . Lozovskii . V.R. . Novikov . I.V. . Cambridge University Press . 2000 . 9780521545822 . Benton, M.J. . Cambridge . 140–159 . Tetrapod biostratigraphy of the Triassic of Eastern Europe . Shishkin, M.A. . Unwin, D.M. . Kurochkin, E.N..
3. Shishkin . M.A. . Sennikov . A.G. . Novikov . I.V. . Ilyina . N.V. . 2006 . Differentiation of Tetrapod Communities and Some Aspects of Biotic Events in the Early Triassic of Eastern Europe . Paleontological Journal . 40 . 1 . 1–10 . 10.1134/S0031030106010011 . 129895753.
4. Tverdokhlebov . Valentin P. . Tverdokhlebova . Galina I. . Surkov . Mikhail V. . Benton . Michael J. . 2003-01-01 . Tetrapod localities from the Triassic of the SE of European Russia . Earth-Science Reviews . en . 60 . 1 . 1–66 . 10.1016/S0012-8252(02)00076-4 . 0012-8252.