Besano Formation

The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a short but fossiliferous succession of dolomite and black shale, is famous for its preservation of Middle Triassic marine life including fish and aquatic reptiles. It is exposed in the vicinity of Monte San Giorgio and is among the formations responsible for the area being designated as a UNESCO World Heritage Site.

Besano Formation Stratigraphic range: Anisian-Ladinian (Illyrian-Fassanian) ~247–235 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Lithology
Primary	Dolomite, shale
Location
Coordinates	45.9°N 8.9°E / 45.9; 8.9
Approximate paleocoordinates	7.5°N 21.0°E / 7.5; 21.0
Region	Lombardy, Piedmont Ticino
Country	Italy   Switzerland
Extent	Southwestern Limestone Alps
Type section
Named for	Besano
Besano Formation (Switzerland)

In Switzerland, it is also known as the Grenzbitumenzone.[1][2]

Fossil content

The formation is highly fossiliferous and has among others provided the following fossils:

• Reptiles
  • Askeptosaurus italicus
  • Clarazia schinzi
  • Cyamodus hildegardensis
  • Cymbospondylus buchseri
  • Eusaurosphargis dalsassoi
  • Helveticosaurus zollingeri
  • Hescheleria rubeli
  • Lariosaurus buzzii
  • Macrocnemus cf. fuyuanensis
  • Macrocnemus bassanii
  • Nothosaurus giganteus
  • Nothosaurus cf. juvenilis
  • Pachypleurosaurus edwardsi
  • Paraplacodus broilii
  • Serpianosaurus mirigiolensis
  • Tanystropheus longobardicus
  • Ticinosuchus ferox
  • Mixosaurus sp.
• Fish
  • Bobasatrania ceresiensis
  • Ctenognathichthys bellottii
  • Eosemionotus diskosomus
  • Luganoia lepidosteoides
  • Meridensia meridensis
  • Peltopleurus lissocephalus
  • Pholidopleurus ticinensis
  • Platysiagum minus
  • Ptycholepis barboi
  • P. magnus
  • P. schaefferi
  • Saurichthys costasquamosus
  • S. curionii
  • Ticinolepis crassidens
  • T. longaeva
  • Hybodus cf. plicatilis
  • ?Acrodus lateralis
• Invertebrates
  • ?Mojsisovicsteuthis sp.

References

1. López Arbello et al., 2016
2. Stockar et al., 2012

Bibliography

• López Arbarello, Adriana; Toni Bürgin; Heinz Furrer, and Rudolf Stockar. 2016. New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland). PeerJ 4. e2234. doi:10.7717/peerj.2234 ISSN 2167-8359
• Stockar, Rudolf; Peter O. Baumgartner, and Daniel Condon. 2012. Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland). Swiss Journal of Geosciences 105. 85–108. doi:10.1007/s00015-012-0093-5 ISSN 1661-8734

Further reading

• A. López Arbarello, T. Bürgin, H. Furrer and R. Stockar. 2019. Taxonomy and phylogeny of Eosemionotus Stolley, 1920 (Neopterygii: Ginglymodi) from the Middle Triassic of Europe. Palaeontologia Electronica 22(1.10A):1-64
• S. Renesto, G. Binelli, and H. Hagdorn. 2014. A new pachypleurosaur from the Middle Triassic Besano Formation of Northern Italy. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 271(2):151-168
• J. Müller. 2005. The anatomy of Askeptosaurus italicus from the Middle Triassic of Monte San Giorgio and the interrelationships of thalattosaurs (Reptilia, Diapsida). Canadian Journal of Earth Sciences 42:1347-1367
• O. Rieppel. 1998. The status of the sauropterygian reptile genera Ceresiosaurus, Lariosaurus, and Silvestrosaurus from the Middle Triassic of Europe. Fieldiana: Geology, new series 38:1-46
• O. Rieppel. 1989. A New Pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 323(1212):1-73
• P. M. Sander. 1989. The large ichthyosaur Cymbospondylus buchseri, sp. nov. from the Middle Triassic of Monte San Giorgio (Switzerland), with a survey of the genus in Europe. Journal of Vertebrate Paleontology 9(2):163-173
• O. Rieppel. 1987. Clarazia and Hescheleria: A re-investigation of two problematic reptiles from the Middle Triassic of Monte San Giorgio (Switzerland). Palaeontographica, Abt. A, Palaeozoologie-Stratigraphie 195(4-6):101-129
• O. Rieppel. 1981. The Hybodontiform Sharks from the Middle Triassic of Mte. San Giorgio, Switzerland. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 161:324-353
• H. Rieber. 1973. Die Triasfauna der Tessiner Kalkalpen: XXII. Cephalopoden aus der Grenzbitumenzone (Mittlere Trias) des Monte San Giorgio (Kanton Tessin, Schweiz). Schweizerische Palaeontologische Abhandlungen 93:1-96
• B. Krebs., E. Kuhn-Schnyder und B. Peyer 1965 Die Triasfauna der Tessiner Kalkalpen. XIX. Ticinosuchus ferox nov. gen. nov. sp. [E. Kuhn-Schnyder and B. Peyer: The Triassic fauna of the Ticino Limestone Alps. XIX. Ticinosuchus ferox nov. gen. nov. sp.]. Schweizerische Paläontologische Abhandlungen, Memoires suisses de Paleontologie 81:1-140
• E. Kuhn-Schnyder. 1962. Ein weiterer Schädel von Macrocnemus bassanii Nopcsa aus der anisischen Stufe der Trias des Monte San Giorgio (Kt. Tessin, Schweiz). Palaeontologische Zeitschrift 36:110-133
• J. Brough. 1939. The Triassic fishes of Besano, Lombardy 1-117