Rybinskian Gorizont

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.[2][3][4]

  1. ^ Novikov, I. V. (2018-12-01). "New Stage of Recovery of East European Tetrapod Community after Permian–Triassic Crisis". Paleontological Journal. 52 (7): 791–795. doi:10.1134/S0031030118070080. ISSN 1555-6174.
  2. ^ a b Shishkin, M.A.; Ochev, V.G.; Lozovskii, V.R.; Novikov, I.V. (2000). "Tetrapod biostratigraphy of the Triassic of Eastern Europe". In Benton, M.J.; Shishkin, M.A.; Unwin, D.M.; Kurochkin, E.N. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge: Cambridge University Press. pp. 140–159. ISBN 9780521545822.
  3. ^ a b 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. doi:10.1134/S0031030106010011. S2CID 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. 60 (1): 1–66. doi:10.1016/S0012-8252(02)00076-4. ISSN 0012-8252.