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Moltrasio Formation
Stratigraphic range: Middle Sinemurian-Lower Pliensbachian ~196–188 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Outcrop
Type	Geological formation
Unit of	Monte Generoso Basin
Sub-units	Osteno Outcrop
Underlies	Domaro Formation
Overlies	Saltrio Formation Sedrina Limestone
Thickness	200 m
Lithology
Primary	Limestone
Location
Coordinates	46°00′N 9°06′E / 46.0°N 9.1°E / 46.0; 9.1
Approximate paleocoordinates	33°12′N 15°36′E / 33.2°N 15.6°E / 33.2; 15.6
Region	Lombardy
Country	Italy   Switzerland
Type section
Named for	Moltrasio
Named by	Antonio Stoppani
Year defined	1857
Moltrasio Formation (Italy)Show map of ItalyMoltrasio Formation (Lombardy)Show map of Lombardy

The Moltrasio Formation also known as the Lombardische Kieselkalk Formation is a geological formation in Italy and Switzerland. This Formation mostly developed in the Lower or Middle Sinemurian stage of the Lower Jurassic, where on the Lombardian basin tectonic activity modified the current marine and terrestrial habitats. Here it developed a series of marine-related depositional settings, represented by an outcrop of 550–600 m of grey Calcarenites and Calcilutites with chert lenses and marly interbeds, that recovers the Sedrina, Moltrasio and Domaro Formations. This was mostly due to the post-Triassic crisis, that was linked locally to tectonics. The Moltrasio Formation is considered a continuation of the Sedrina Limestone and the Hettangian Albenza Formation, and was probably a shallow water succession, developed on the passive margin of the westernmost Southern Alps. It is known due to the exquisite preservation observed on the Outcrop in Osteno, where several kinds of marine biota have been recovered.

Fossils

Exceptional fossilization

Apart from the Eocene of Monte Bolca, the Sinemurian of Osteno is the only fossil deposit in Italy in which soft bodies are preserved. The Osteno site was discovered in 1964. It was recovered from a series of 6 metres (20 ft) package of fine laminated, gray, spongiolitic, micritic limestone. Coroniceras bisulcatum allowed to date the outcrop as the Bucklandi zone, lower Sinemurian. The outcrop is a good documentation of a particularly complete fauna and flora of the Lower Jurassic which is not exactly common in the Southern Alps. The Osteno outcrop, part of the formation, is worldwide known due to the exceptional preservation of mostly marine biota, including rare fossilized components, helping to understand the ecosystems of the local Sinemurian margin of the Monte Generoso Basin. The high local variety of fossils found is most likely due to unique conditions of preservation, where phosphatized soft tissues have not been observed in any fish or polychaetes, but they are common in crustaceans (33%) and also occur in a smaller percentage of teuthids (14%). Soft part preservation through phosphatization in this deposit includes the muscles and branchia of Crustaceans, fish tissues, and the digestive tracts of coleoids, polychaetes, and nematodes. These fossils are interpreted as having been preserved in a stagnant, restricted basin with anoxic conditions likely within the sediment pore waters.

Nematoida

Annelida

Crustacea

Genus	Species	Material	Location	Notes	Images
Aeger	A. foesteri A. muensteri A. robustus A. rostrospinatus A. elongatus A. macropus	Multiple specimens fairly preserved	Osteno Outcrop	A decapod, type member of the family Aegeridae. This genus is the most abundant local crustacean, and was a shrimp-like creature that was probably necrophagous.
Coleia	C. vialiii C. medilerranea C. cf. antiqua C. pinnnai	Multiple specimens fairly preserved	Osteno Outcrop	A decapod, type member of the family Coleiidae. Probably a bottom dweller predatory crustacean.
Eryma	E. sinemuriana	41 specimens, fairly preserved	Osteno Outcrop	A decapod, type member of the family Erymidae. The species was originally identified as Pustulina sinemuriana.
Glyphea	G. tricarinata	137 complete and fragmentary specimens	Osteno Outcrop	A decapod, type member of the family Erymidae. The species was originally identified as Pustulina sinemuriana.
Mecochirus	M. germari	81 complete and fragmentary specimens,	Osteno Outcrop	A decapod, member of the family Mecochiridae. Rather rare compared to other local crustacean genera.
Ostenosculda	O. teruzzii	Single Specimen fairly preserved	Osteno Outcrop	A mantis shrimp
Palaeastacus	P. meyeri	Multiple specimens fairly preserved	Osteno Outcrop	A decapod, member of the family Erymidae. The species was originally included in the genus Eryma as E. meyeri, although the specimens reveal morphological characters diagnostic of Palaeastacus.
Phlyctisoma	P. sinemuriana	10 specimens, in a fairly good state of preservation	Osteno Outcrop	A decapod, type member of the family Erymidae. The species was originally identified as Pustulina sinemuriana.
Pseudoglyphea	P. ancylochelis	7 complete specimens, in a fairly good state	Osteno Outcrop	A decapod, member of the family Litogastroidae. Probably a bottom dweller predatory crustacean.
Teruzzicheles	T. popeyei	Various specimens fairly preserved	Osteno Outcrop	A decapod belonging to the family Polychelidae

Xiphosurida

Thylacocephala

Cephalopoda

Echinoderms

Hemichordata

Chondrichthyes

Actinopterygii

Genus	Species	Material	Location	Notes	Images
Cosmolepis?	C. ornatus?	MSNM V617, complete specimen	Osteno Outcrop	A primitive actinopterygiian, member of the order Palaeonisciformes. A late surviving representative of the family. The specimens may not represent members of the genus.
Dapedium	D. sp.	MSNM V630, caudal fin with associated scales	Osteno Outcrop	A primitive actinopterygiian, type member of the family Dapediidae inside Holostei. Probably a Coral Environment wanderer.
Furo	F. ("Eugnathus") sp.	MSNM V659, skull & anterior truncal body	Osteno Outcrop	A primitive actinopterygiian, type member of the family Furidae inside Ionoscopiformes. An enlongated Gar-alike taxon.
Pholidophorus	P. cf.bechei	MSNM V621, complete specimen MSNM V556, isolated complete skull Multiple referred specimens	Osteno Outcrop	A primitive actinopterygiian, type member of the family Pholidophoridae inside Teleostei. Open water swimmer, probably forming schools. It is the main fish recovered on the formation.
Pholidolepis	P. sp.	MSNM V409, complete specimen MSNM V594, isolated complete skull Multiple referred specimens	Osteno Outcrop	A primitive Actinopterygiian, member of the family Pholidophoridae inside Teleostei. Open water swimmer, probably forming schools.
Palaeonisciformes?	Indeterminate	MSNM V618-19, skull & toracic section specimen Other 3 Specimens	Osteno Outcrop	Primitive actinopterygiians, suggested to be members of the order Palaeonisciformes. The features inferred to refer this specimens aren´t enought to confirm the family association.
Peripeltopleurus?	P. sp.	MSNM V659, almost complete specimen lacking the tail	Osteno Outcrop	A primitive actinopterygiian, member of the family Peltopleuridae inside Neopterygii. Probably represents the only known Jurassic survivor of the order Peltopleuriformes

Sarcopterygii

Plants

Genus	Species	Material	Location	Notes	Images
Brachyphyllum	B. saportum B. spp.	Branched Shoots	Osteno Outcrop Dintorni di Moltrasio	A coniferophytan, member of the family Cheirolepidiaceae inside Pinopsida.
Clathropteris	C. platyphylla	Fronds	Carate-Lario	A Fern, member of the family Dipteridaceae
Ctenopteris	C. grandis	Fronds	Moltrasio	A Fern, member of the family Polypodiaceae
Equisitites	E. bunburyanus	Stems	Osteno Outcrop	A Horsetail, member of the family Equisetaceae inside Equisetales. A freshwater-related plant, that grew as fast as modern bamboo on tropical settings.
Lomatopteris	L. jurensis	Fronds	Carate-Lario	A "Seed Fern", Affinities with Cyclopteridaceae inside Pteridospermatophyta.
Otozamites	O. bunburyanus O. bechei O. latior O. brevifolius O. pterophylloides O. sp.	Leaflets	Osteno Outcrop Moltrasio Carate-Lario	A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings.
Pachypteris	P. cf. rhomboidalis	Fronds	Osteno Outcrop	A "Seed Fern", member of the family Corystospermaceae inside Corystospermales.
Pagiophyllum	P. peregrinum P. sp.	Branched Shoots	Osteno Outcrop Carate-Lario	A coniferophytan, member of the family Araucariaceae inside Pinopsida.
Thinnfeldia	T. rhomboidalis T. obtusa	Fronds	Carate-Lario	A "Seed Fern", member of the family Corystospermaceae inside Corystospermales.
Williamsonia	W. sp.	Reproductive Organ	Osteno Outcrop	A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings.
Widdringtonites	W. baehmanni	Branched Shoots	Mombello	A coniferophytan, member of the family Araucariaceae or Cupressaceae inside Pinopsida.
Zamites	Z. sp.	Leaflets	Osteno Outcrop	A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings.

See also

• List of fossiliferous stratigraphic units in Italy
• Calcare di Sogno, Toarcian fossiliferous formation of Lombardy
• Saltrio Formation, Sinemurian fossiliferous formation of Lombardy
• Rotzo Formation, Pliensbachian fossiliferous formation of Veneto
• Coimbra Formation, Sinemurian fossiliferous formation of Portugal
• Aganane Formation, Pliensbachian Formation of Morocco

References

1. Stoppani A. (1857). Studi geologici e paleontologici sulla Lombardia. 461 pp. Tipografia Turati, Milano
2. ^ Muttoni, G.; Erba, E.; Kent, D. V.; Bachtadse, V. (2005). "Mesozoic Alpine facies deposition as a result of past latitudinal plate motion". Nature. 434 (7029): 59–63. Bibcode:2005Natur.434...59M. doi:10.1038/nature03378. hdl:2434/30440. PMID 15744297. S2CID 4316860.
3. ^ Jadoul, F.; Galli, M. T. (2008). "The Hettangian shallow water carbonates after the Triassic-Jurassic biocalcification crisis: The Albenza Formation in the western Southern Alps". Rivista Italiana di Paleontologia e Stratigrafia. 114 (3): 453–470. Retrieved 2 May 2023.
4. Sarti, M.; Bosellini, A.; Winterer, E. L. (1992). "Basin Geometry and Architecture of a Tethyan Passive Margin, Southern Alps, Italy: Implications for Rifting Mechanisms: Chapter 13: African and Mediterranean Margins". AAPG Special Volumes. 115 (5): 241–258. Retrieved 2 May 2023.
5. ^ Pinna, G. (1985). "Exceptional preservation in the Jurassic of Osteno". Philosophical Transactions of the Royal Society of London B: Biological Sciences. 311 (1148): 171–180. Bibcode:1985RSPTB.311..171P. doi:10.1098/rstb.1985.0149. Retrieved 2 May 2023.
6. ^ Pinna, G. (2000). "Die Fossillagerstätte im Sinemurium (Lias) von Osteno, Italien". Europäische Fossillagerstätten. Vol. 3. pp. 91–136. doi:10.1007/978-3-642-57198-5_13. ISBN 978-3-642-62975-4. Retrieved 2 May 2023.
7. Bottjer, D. J.; Etter, W.; Tang, C. M.; Hagadorn, J. W. (2002). Exceptional fossil preservation: a unique view on the evolution of marine life. Columbia University Press. p. 421. ISBN 9780231102544. Retrieved 2 May 2023.
8. Wilby, P. R.; Briggs, D. E. (1997). "Taxonomic trends in the resolution of detail preserved in fossil phosphatized soft tissues". Geobios. 30 (8): 493–502. Bibcode:1997Geobi..30..493W. doi:10.1016/S0016-6995(97)80056-3. Retrieved 2 May 2023.
9. ^ Arduini, P.; Pinna, G.; Teruzzi, G. (1983). "Eophasma jurassicum ngn sp., a new fossil nematode of the Sinemurian of Osteno in Lombardy". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 124 (1–2): 61–64.
10. Poinar, G.O. (2011). The Evolutionary History of Nematodes: As revealed in stone, amber and mummies. Nematology Monographs and Perspectives. 9. Brill Publishers. ISBN 9789047428664.
11. ^ Arduini, P.; Pinna, G.; Teruzzi, G. (1982). "Melanoraphia maculata ngn sp., a new fossil polychaete of the Sinemurian of Osteno in Lombardy". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 123 (4): 462–468. Retrieved 2 May 2023.
12. ^ Pinna, G. (1967). "Decouverte d'une nouvelle faune a crustaces du Sinemurien inferieur dans la region du Lac Ceresio (Lombardie, Italie)". Atti Soc. It. Sci. Nat. Museo Milano. 106 (4): 183–185.
13. ^ Garassino, A.; Teruzzi, G. (1990). "The genus Aeger Münster, 1839 in the Sinemurian of Osteno in Lombardy (Crustacea, Decapoda)". Atti della società italiana di scienze naturali e del museo civico di storia naturale di Milano. 131 (5): 105–136. Retrieved 2 May 2023.
14. ^ Pinna, G. (1969). "Due nuovi esemplari di Coleia vialiii Pinna, del Sinemuriano inferiore di Osteno in Lombardia (Crustacea Decapoda)". Ann. Mus. St. Nat. Genova. 77 (12): 626–632.
15. Teruzzi, G. (1990). "The genus «Coleia» Broderip, 1835 (Crustacea, Decapoda) in the Sinemurian of Osteno in Lombardy". Atti della Società italiana di Scienze naturali e del Museo Civico di Storia naturale di Milano. 131 (4): 85–104. Retrieved 2 May 2023.
16. ^ Duffin, C. J. (1998). "Ostenoselache stenosoma ngn sp., a new neoselachian shark from the Sinemurian (Early Jurassic) of Osteno (Lombardy, Italy)" (PDF). Società Italiana di Scienze Naturali. 9 (7): 1–27. Retrieved 2 May 2023.
17. ^ Garassino, A . (1996). "The family Erymidae Van Straelen, 1924 and the superfamily Glypheoidea Zittel, 1885 in the Sinemurian of Osteno in Lombardy". AAI Soc. It. Sci.RWT. Museo Civ. Stor. Mu. Milano. Milano. 135 (11): 333–373. Retrieved 2 May 2023.
18. Devillez, J.; Charbonnier, S. (2019). "Review of the Early and Middle Jurassic erymid lobsters (Crustacea: Decapoda) [Révision des Érymides (Crustacea: Decapoda) du Jurassique inférieur et moyen]". Bulletin de la Société géologique de France. 190 (1): 121–134. doi:10.1051/bsgf/2019005. S2CID 196643332.
19. ^ Devillez, J.; Charbonnier, S. (2017). "The genus Eryma Meyer, 1840 (Crustacea: Decapoda: Erymidae): new synonyms, systematic and stratigraphic implicationsLe genre Eryma Meyer, 1840 (Crustacea: Decapoda: Erymidae): nouveaux synonymes, implications systématique et stratigraphique". Bulletin de la Société géologique de France. 188 (3): 1–15. Retrieved 2 May 2023.
20. "Another piece in the puzzle of mantis shrimp evolution – fossils from the Early Jurassic Osteno Lagerstätte of Northern Italy". Comptes Rendus Palevol. 22 (2): 17–31. 2023. Retrieved 2 May 2023.
21. Audo, Denis; Charbonnier, Sylvain (2022-12-28). "Teruzzicheles popeyei, an early Sinemurian polychelid lobster from the Osteno Lagerstätte (Italy)". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 306 (3): 187–194. doi:10.1127/njgpa/2022/1103. ISSN 0077-7749. S2CID 254820598.
22. ^ Lamsdell, J. C.; Teruzzi, G.; Pasini, G.; Garassino, A. (2021). "A new limulid (Chelicerata, Xiphosurida) from the Lower Jurassic (Sinemurian) of Osteno, NW Italy". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 300 (1): 1–10. doi:10.1127/njgpa/2021/0974. S2CID 234814276.
23. Arduini, P.; Pinna, G.; Teruzzi, G. (1984). "Ostenocaris nom. nov. pro Ostenia". Atli Del/A Societcl Iraliwzn di Sc: Ienze Naturali e del Museo Civico di Storia Naturale di Milano, Miiano. 125 (1–2): 48.
24. Arduini, P.; Pinna, G.; Teruzzi, G. (1982). "Il giacimento sinemuriano di Osteno in Lombardia". Palaeontology, Essential of Historical Geology. Mucchi, Modena. 134 (2): 495–522.
25. Pinna, G.; Arduini, P.; Pesarini, C.; Teruzzi, G. (1985). "Some controversial aspects of the morphology and anatomy of Ostenocaris cypriformis (Crustacea, Thylacocephala)". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 76 (2–3): 373–379. Bibcode:1985EESTR..76..373P. doi:10.1017/S0263593300010580. S2CID 85401617. Retrieved 2 May 2023.
26. Pinna, Ð. (1972). "Rinvenimento di un raro cefalopode coleoideo nel giacimento sinemuriano di Osteno in Lombardia". Atti de la SocietaÁ Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 113 (1): 141–149.
27. ^ Garassino, A.; Donovan, D. T. (2000). "A new family of coleoids from the Lower Jurassic of Osteno, Northern Italy". Palaeontology. 43 (6): 1019–1038. Bibcode:2000Palgy..43.1019G. doi:10.1111/1475-4983.00160. S2CID 129455509. Retrieved 2 May 2023.
28. ^ Jaselli, L. (2021). "Reappraisal of the Lower Jurassic crinoid fauna of Lombardy (Italy): insights on regional museum collections". Bollettino della Società Paleontologica Italiana. 60 (2): 112. Retrieved 19 October 2023.
29. ^ Arduini, P.; Pinna, G.; Teruzzi, G. (1981). "Megaderaion sinemuriense n. g. n. sp., a new fossil enteropneust of the Sinemurian of Osteno in Lombardy". Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano. 122 (2): 104–108. Retrieved 2 May 2023.
30. ^ Duffin, C. J. (1991). "A myriacanthid holocephalan (Chondrichthyes) from the Sinemurian (Lower Jurassic) of Osteno (Lombardy, Italy)". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 132 (23): 293–308. Retrieved 3 May 2023.
31. Duffin, C. J. (1987). "Palaeospinax pinnai n. sp., a new Palaeospinacid shark from the Sinemuvian (Lower Jurassic) of Osteno (Lombardy, Italy)". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 128 (1): 185–202.
32. Duffin, Christopher J.; Garassino, Alessandro; Pasini, Giovanni (2023). "Squaloraja; Riley 1833 (Holocephala: Squalorajidae) from the Lower Jurassic of Osteno Konservat-Lagerstätte (Como, NW Italy)". Natural History Sciences. 10 (1). doi:10.4081/nhs.2023.642. ISSN 2385-0922. S2CID 258822179.
33. ^ Duffin, C. J.; Patterson, C. (1993). "I Pesci Fossili di Osteno: una Nuova Finestra sulla Vita del Giurassico Inferiore". Paleocronache. 34 (2): 18–38. Retrieved 3 May 2023.
34. Franceschi, Fabio; Marrama, Giuseppe; Carnevale, Giorgio (2024). "The enigmatic "palaeoniscoid" fishes from the Lower Jurassic (Sinemurian) of the Southern Alps (Osteno, Como, Italy)" (PDF). Paleodays. XXIV (4): 62.
35. Franceschi, Fabio; Marrama, Giuseppe; Carnevale, Giorgio (2024). "The enigmatic "palaeoniscoid" fishes from the Lower Jurassic (Sinemurian) of the Southern Alps (Osteno, Como, Italy)" (PDF). Paleodays. XXIV (4): 62.
36. Franceschi, Fabio; Marrama, Giuseppe; Carnevale, Giorgio (2024). "The enigmatic "palaeoniscoid" fishes from the Lower Jurassic (Sinemurian) of the Southern Alps (Osteno, Como, Italy)" (PDF). Paleodays. XXIV (4): 62.
37. Franceschi, Fabio; Marrama, Giuseppe; Carnevale, Giorgio (2024). "The enigmatic "palaeoniscoid" fishes from the Lower Jurassic (Sinemurian) of the Southern Alps (Osteno, Como, Italy)" (PDF). Paleodays. XXIV (4): 62.
38. Franceschi, F.; Marramà, G.; Carnevale, G. (2023). "Reassessment of a putative peltopleurid fish from the Sinemurian (Lower Jurassic) of Osteno (Como, Italy): preliminary results" (PDF). PALEODAYS-Abstract Book. XXIII Edizione delle Giornate di Paleontologia-2023. 23 (1): 51.
39. ^ Bonci, M. C.; Vanucci, G. (1986). "I vegetali sinemuriani di Osteno (Lombardia)". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 127 (2): 107–127.
40. ^ Sordelli, F. (1896). "Flora liasica ed infraliasica" (PDF). Flora fossilis Insubrica. Studi sulla vegetazione di Lombardia durante i tempi geologici: 38–55.

• Geologic formations of Italy
• Jurassic System of Europe
• Early Jurassic Europe
• Sinemurian Stage
• Limestone formations
• Paleontology in Italy
• Geography of Lombardy