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. In Switzerland, it is also known as the Grenzbitumenzone.[1][2][3][4][5][6][7][8]
| Besano Formation Stratigraphic range: Late Anisian (Illyrian) ~ | |
|---|---|
| Type | Geological formation |
| Underlies | San Giorgio Dolomite |
| Overlies | Lower San Salvatore Dolomite |
| Lithology | |
| Primary | Dolomite, shale |
| Location | |
| Coordinates | 45.9°N 8.9°E |
| Approximate paleocoordinates | 7.5°N 21.0°E |
| Region | Lombardy, Piedmont, Ticino |
| Country |  Italy Switzerland |
| Extent | Southwestern Limestone Alps |
| Type section | |
| Named for | Besano |
  Besano Formation (Switzerland) | |
Paleobiota
The formation is highly fossiliferous and has provided the following fossils:
Reptiles
| Reptiles of the Besano Formation | |||
|---|---|---|---|
| Genus | Species | Notes | Images |
| Askeptosaurus[9] | A. italicus | An askeptosauroid thalattosaur | |
| Besanosaurus | B. leptorhynchus | A large merriamosaurian ichthyosaur | |
| Clarazia[10] | C. schinzi | A claraziid thalattosaur | |
| Cyamodus | C. hildegardis | A cyamodontid placodont | |
| Cymbospondylus[11] | C. buchseri | A large cymbospondylid ichthyosaur | |
| Eusaurosphargis | E. dalsassoi | A possible helveticosaurid | |
| Helveticosaurus | H. zollingeri | A helveticosaurid | |
| Hescheleria[10] | H. rubeli | A claraziid thalattosaur | |
| Macrocnemus | M. bassanii | A tanystropheid | |
| M. cf. fuyuanensis | A tanystropheid | ||
| Mixosaurus | M. cornalianus | A common mixosaurid ichthyosaur | |
| Nothosaurus | N. giganteus | A large nothosaur, sometimes known as Paranothosaurus amsleri | |
| N. cf. juvenilis | A small nothosaur | ||
| Odoiporosaurus[12] | O. terruzzii | A pachypleurosaur | |
| Paraplacodus | P. broilii | A basal placodont | |
| Serpianosaurus[13] | S. mirigolensis | A common pachypleurosaur | |
| Silvestrosaurus | S. buzzii | A small lariosaurine nothosaur, sometimes considered a species of Lariosaurus[14] | |
| Tanystropheus | T. hydroides | A large tanystropheid | |
| T. longobardicus | A tanystropheid | ||
| Ticinosuchus | T. ferox | A suchian archosaur | |
Bony fish
| Osteichthyans of the Besano Formation | |||
|---|---|---|---|
| Genus | Species | Notes | Images |
| Aetheodontus[15] | A. besanensis | A small "perleidid" neopterygian | |
| Altisolepis[15][16] | A. bellipinnis | A small "perleidid" neopterygian | |
| A. elongignathus | A small "perleidid" neopterygian | ||
| Besania?[15] | B. micrognathus | A small halecostomian neopterygian, provenance uncertain | |
| Birgeria[15][17] | B. stensioei | A large birgeriid chondrostean | |
| Bobasatrania[15] | B. ceresiensis | A bobasatraniiform chondrostean | |
| Cephaloxenus[15] | C. macropterus | A small peltopleuriform neopterygian | |
| C. squamiserratus | A small peltopleuriform neopterygian | ||
| Colobodus[15] | C. bassanii | A large colobodontid neopterygian | |
| Crenilepis[15] | C. "divaricatus" | A large colobodontid neopterygian | |
| Ctenognathichthys[15][18] | C. bellottii | A small "perleidiform" neopterygian | |
| Eoeugnathus[15][19] | E. megalepis | A small halecomorph neopterygian | |
| Eosemionotus[15][20] | E. ceresiensis | A small macrosemiid ginglymodian | |
| Gracilignathichthys[15] | G. microlepis | A small pholidopleuriform neopterygian | |
| Gyrolepis[15] | G. sp. | A palaeoniscid actinopterygian primarily based on scales | |
| Habroichthys[15] | H. griffithi | A small peltopleuriform neopterygian | |
| Holophagus?[15][21] | cf. H. picenus | A large coelacanth possibly referable to H. picenus | |
| Luganoia[15] | L. lepidosteoides | A small luganoiiform neopterygian | |
| Meridensia[15] | M. meridensis | A small "perleidid" neopterygian | |
| Nannolepis[15] | N. sp. | A small peltopleuriform neopterygian | |
| Ophiopsis[15] | O. sp. | A small halecomorph neopterygian | |
| Peltoperleidus[15][16] | P. ducanensis | A small "perleidid" neopterygian | |
| P. macrodontus | A small "perleidid" neopterygian | ||
| P. obristi | A small "perleidid" neopterygian | ||
| P. triseries | A small "perleidid" neopterygian | ||
| Peltopleurus[15][22] | P. lissocephalus | A small peltopleuriform neopterygian | |
| P. nothocephalus | A small peltopleuriform neopterygian | ||
| P. rugosus | A small peltopleuriform neopterygian | ||
| Peripeltopleurus[15] | P. vexillipinnis | A small peltopleuriform neopterygian | |
| Pholidopleurus[15] | P. ticinensis | A small pholidopleuriform neopterygian | |
| Placopleurus[15] | P. besanensis | A small peltopleuriform neopterygian | |
| P. gracilis | A small peltopleuriform neopterygian | ||
| Platysiagum[15] | P. minus | A small platysiagid neopterygian | |
| Ptycholepis[15] | P. barboi | A small ptycholepiform actinopterygian | |
| P. magnus | A small ptycholepiform actinopterygian | ||
| P. priscus | A small ptycholepiform actinopterygian | ||
| P. schaefferi | A small ptycholepiform actinopterygian | ||
| Saurichthys | S. breviabdominalis | A small saurichthyid chondrostean | |
| S. costasquamosus | A large saurichthyid chondrostean | ||
| S. paucitrichus | A small saurichthyid chondrostean | ||
| S. rieppeli | A large saurichthyid chondrostean | ||
| Stoppania[23] | S. ornata | A small polzbergiid neopterygian originally misidentified as a species of Dipteronotus | |
| Ticinepomis[24] | T. peyeri | A small latimeriid coelacanth | |
| Ticinolepis[7][15] | T. crassidens | A small basal ginglymodian originally misidentified as Archaeosemionotus | |
| T. longaeva | A small basal ginglymodian originally misidentified as Archaeosemionotus | ||
Cartilaginous fish
| Chondrichthyans of the Besano Formation | |||
|---|---|---|---|
| Genus | Species | Notes | Images |
| Acrodus | A. georgii | A durophagous hybodont shark |  |
| Acronemus[25] | A. tuberculatus | An unusual euselachian shark |  |
| Asteracanthus | A. reticulatus | A durophagous hybodont shark |  |
| Hybodus | H. cf. plicatilis | A predatory hybodont shark | |
| Palaeobates | P. angustissimus | A durophagous hybodont shark |  |
Invertebrates
- Ammonoids (Celtites, Protrachyceras, Serpianites, Ticinites, Repossia, Flexoptychites, Proarcestes, Stoppaniceras, Parakellnerites, etc.)
- Belemnoids (Breviconoteuthis, Phragmoteuthis, Mojsisovicsteuthis, etc.)
- Bivalves (Daonella, Peribositria, etc.)
- Conodonts (Gondolella, etc.)
- Crustaceans (Antrimpos)[26]
- Gastropods (Frederikella, Worthenia, Trachynerita, Omphaloptycha, etc.)[27]
- Nautiloids (Michelinoceras, etc.)
Plants
- Calcareous algae (Diplopora)
- Voltzialean conifers (Voltzia)
References
- Bernasconi, Stefano Michele (1991). "Geochemical and microbial controls on dolomite formation and organic matter production/preservation in anoxic environments: a case study from the Middle Triassic Grenzbitumenzone, Southern Alps (Ticino, Switzerland)". ETH Zurich Dissertation: 1–198.
- 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.
- Furrer, Heinz (1995). "The Kalkschieferzone (Upper Meride Limestone, Ladinian) near Meride (Canton Ticino, Southern Switzerland) and the evolution of a Middle Triassic intraplatform basin". Eclogae Geologicae Helvetiae. 88 (3): 827–852.
- Röhl, H.J.; Schmid-Röhl, A.; Furrer, H.; Frimmel, A.; Oschmann, W.; L., Schwark (2001). "Microfacies, geochemistry and palaeoecology of the Middle Triassic Grenzbitumenzone from Monte San Giorgio (Canton Ticino, Switzerland)". Geologia Insubria. 6 (1): 1–13.
- 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.
- Stockar, Rudolf; Baumgartner, Peter O.; Condon, Daniel (15 May 2012). "Integrated Ladinian bio-chronostratigraphy and geochrononology of Monte San Giorgio (Southern Alps, Switzerland)" (PDF). Swiss Journal of Geosciences. 105 (1): 85–108. doi:10.1007/s00015-012-0093-5. ISSN 1661-8734. S2CID 129644478.
- López-Arbarello, Adriana; Bürgin, Toni; Furrer, Heinz; Stockar, Rudolf (2016-07-19). "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. PMC 4957996. PMID 27547543.
- Rieppel, Olivier (2019). Mesozoic Sea Dragons: Triassic Marine Life from the Ancient Tropical Lagoon of Monte San Giorgio. Bloomington, IN: Indiana University Press. ISBN 978-0-253-04013-8.
- Müller, Johannes (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 (7): 1347–1367. Bibcode:2005CaJES..42.1347M. doi:10.1139/e05-030.
- Rieppel, O. (1987). "Clarazia and Hescheleria: a re-investigation of two problematical reptiles from the Middle Triassic of Monte San Giorgio (Switzerland)". Palaeontographica Abteilung A. A195 (4–6): 101–129.
- Sander, P. Martin (1989-06-30). "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. doi:10.1080/02724634.1989.10011750. ISSN 0272-4634.
- Renesto, S.; Binelli, G.; Hagdorn, H. (2014). "A new pachypleurosaur from the Middle Triassic Besano Formation of Northern Italy". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 271 (2): 151. doi:10.1127/0077-7749/2014/0382.
- Rieppel, O.; Greenwood, Peter Humphry (1989-01-04). "A new pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of Monte San Giorgio, Switzerland". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 323 (1212): 1–73. Bibcode:1989RSPTB.323....1R. doi:10.1098/rstb.1989.0001.
- Olivier 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.
- Romano, Carlo (2021). "A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes". Frontiers in Earth Science. 8. doi:10.3389/feart.2020.618853. ISSN 2296-6463.
- Mutter, Raoul J.; Herzog, Annette (2004-12-10). "A new genus of Triassic actinopterygian with an evaluation of deepened flank scales in fusiform fossil fishes". Journal of Vertebrate Paleontology. 24 (4): 794–801. doi:10.1671/0272-4634(2004)024[0794:ANGOTA]2.0.CO;2. ISSN 0272-4634.
- Romano, C. & Brinkmann, W. (2009). "Reappraisal of the lower actinopterygian Birgeria stensioei ALDINGER, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic of Monte San Giorgio (Switzerland) and Besano (Italy)". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 252: 17–31. doi:10.1127/0077-7749/2009/0252-0017.
- Tintori, Andrea (1998-11-30). "CTENOGNATHICHTHYS BELLOTTII (DE ALESSANDRI, 1910): NOMENCLATURAL PROBLEMS AND STRATIGRAPHICAL IMPORTANCE OF THIS MIDDLE TRIASSIC ACTINOPTERYGIAN FISH". Rivista Italiana di Paleontologia e Stratigrafia. 104 (3). doi:10.13130/2039-4942/5342. ISSN 2039-4942.
- Herzog, Annette (2003-04-01). "Eine Neubeschreibung der Gattung Eoeugnathus Brough, 1939 (Actinopterygii; Halecomorphi) aus der alpinen Mitteltrias Graubündens (Schweiz)". Paläontologische Zeitschrift (in German). 77 (1): 223–240. doi:10.1007/BF03004570. S2CID 130755597.
- López-Arbarello, Adriana; Bürgin, Toni; Furrer, Heinz; Stockar, Rudolf (2019-02-27). "Taxonomy and phylogeny of Eosemionotus Stolley, 1920 (Neopterygii: Ginglymodi) from the Middle Triassic of Europe". Palaeontologia Electronica. 22 (1): 1–64. doi:10.26879/904. ISSN 1094-8074.
- Rieppel, Olivier (1985). "A second actinistian from the Middle Triassic of Monte San Giorgio, Kanton Tessin, Switzerland". Eclogae Geologicae Helvetiae. 78: 707–713. doi:10.5169/seals-165676.
- Bürgin, Toni (1990-12-01). "Reproduction in Middle Triassic actinopterygians; complex fin structures and evidence of viviparity in fossil fishes". Zoological Journal of the Linnean Society. 100 (4): 379–391. doi:10.1111/j.1096-3642.1990.tb01866.x. ISSN 0024-4082.
- Lombardo, Cristina; Rusconi, Marco; Tintori, Andrea (2008-07-31). "NEW PERLEIDIFORM FROM THE LOWER LADINIAN (MIDDLE TRIASSIC) OF THE NORTHERN GRIGNA (NORTHERN ITALY)". Rivista Italiana di Paleontologia e Stratigrafia. 114 (2). doi:10.13130/2039-4942/5901. ISSN 2039-4942.
- Rieppel, O. (1980). "A new coelacanth from the Middle Triassic of Monte San Giorgio, Switzerland". Eclogae Geologicae Helvetiae. 73 (3): 921–939.
- Rieppel, O. (1982). "A new genus of shark from the Middle Triassic of Monte San Giorgio, Switzerland" (PDF). Palaeontology. 25 (2): 399–412.
- Etter, Walter (1994-04-01). "A new penaeid shrimp (Antrimpos mirigiolensis n. sp., Crustacea, Decapoda) from the Middle Triassic of the Monte San Giorgio (Ticino, Switzerland)". Neues Jahrbuch für Geologie und Paläontologie - Monatshefte. 1994 (4): 223–230. doi:10.1127/njgpm/1994/1994/223.
- Pieroni, Vittorio; Furrer, Heinz (2020-02-12). "Middle Triassic gastropods from the Besano Formation of Monte San Giorgio, Switzerland". Swiss Journal of Palaeontology. 139 (1): 2. doi:10.1186/s13358-019-00201-8. ISSN 1664-2384. S2CID 211089125.
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
- 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
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