The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a thin but fossiliferous succession of dolomite and black shale, is famous for its preservation of Middle Triassic (Anisian–Ladinian) marine life including fish and aquatic reptiles. It is exposed in the Monte San Giorgio and Besano area. It is among the formations responsible for the area being designated as a UNESCO World Heritage Site. In Switzerland, it is also known as the Grenzbitumenzone.[2][3][1][4][5][6][7][8] The Anisian-Ladinian boundary lies in the upper part of the Besano Formation.[1]
^Bernasconi, S.; Riva, A. (1993). "15 - Organic Geochemistry and Depositional Environment of a Hydrocarbon Source Rock: the Middle Triassic Grenzbitumenzone Formation. Southern Alps. Italy/Switzerland.". In Spencer, A.M. (ed.). Generation. Accumulation and Production of Europe's Hydrocarbons III. European Association of Petroleum Geologists. pp. 179–190.
^Etter, Walter (2002). "Monte San Giorgio: remarkable Triassic marine vertebrates". In Bottjer, D.J.; Etter, W.; Hagadorn, J.W.; Tang, C.M. (eds.). Exceptional fossil preservation; a unique view on the evolution of marine life. New York: Columbia University Press. pp. 220–242.