Moltrasio Formation
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.[2] 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.[2] This was mostly due to the post-Triassic crisis, that was linked locally to tectonics.[3] 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.[3][4] It is known due to the exquisite preservation observed on the Outcrop in Osteno, where several kinds of marine biota have been recovered.[5]
Moltrasio Formation | |
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Stratigraphic range: Middle Sinemurian-Lower Pliensbachian ~ | |
Type | Geological formation |
Unit of | Monte Generoso Basin |
Sub-units | Osteno Outcrop |
Underlies | Domaro Formation |
Overlies | Sedrina Limestone |
Thickness | 200 m |
Lithology | |
Primary | Limestone |
Location | |
Coordinates | 46.0°N 9.1°E |
Approximate paleocoordinates | 33.2°N 15.6°E |
Region | Lombardy |
Country | |
Type section | |
Named for | Moltrasio |
Named by | Antonio Stoppani[1] |
Year defined | 1857 |
Moltrasio Formation (Italy) Moltrasio Formation (Lombardy) |
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.[6] Coroniceras bisulcatum allowed to date the outcrop as the Bucklandi zone, lower Sinemurian.[6] 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.[6] 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.[7] 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%).[8] 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.[5]
Nematoida
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Eophasma jurasicum |
|
Osteno Outcrop.[9] |
A nematode, type member of the family Eophasmidae inside Desmoscolecida.[10] A rare find, since nematode fossils are absent in most Mesozoic marine rocks.[9] |
| |
Annelida
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Melanoraphia maculata |
|
Osteno Outcrop.[11] |
A polychaete, member of the group Phyllodocemorpha with incertae sedis assignation. This polychaete was probably an open swimmer more than a subtrate dweller.[11] |
| |
Crustacea
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
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.[13] |
| |
|
Multiple specimens fairly preserved |
Osteno Outcrop |
A decapod, type member of the family Coleiidae. Probably a bottom dweller predatory crustacean.[14] |
| |
|
41 specimens, fairly preserved |
Osteno Outcrop |
A decapod, type member of the family Erymidae. The species was originally identified as Pustulina sinemuriana.[19] |
||
|
137 complete and fragmentary specimens |
Osteno Outcrop |
A decapod, type member of the family Erymidae. The species was originally identified as Pustulina sinemuriana.[19] |
||
|
81 complete and fragmentary specimens, |
Osteno Outcrop |
A decapod, member of the family Mecochiridae. Rather rare compared to other local crustacean genera. |
||
Ostenosculda[20] |
Ostenosculda teruzzii |
Single Specimen fairly preserved |
Osteno Outcrop |
||
|
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.[19] |
||
Phlyctisoma[17] |
|
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.[19] |
|
|
7 complete specimens, in a fairly good state |
Osteno Outcrop |
A decapod, member of the family Litogastroidae. Probably a bottom dweller predatory crustacean.[14] |
||
Teruzzicheles[21] | Teruzzicheles popeyei |
Various specimens fairly preserved |
Osteno Outcrop |
A decapod belonging to the family Polychelidae |
|
Xiphosurida
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Ostenolimulus[22] |
|
|
Osteno Outcrop.[22] |
A horseshoe crab, member of the family Limulidae. This genus represents the oldest Jurassic limulid and only the second xiphosuran known from Italy.[22] Also indicates that this family were a diverse and widespread clade during the Jurassic.[22] |
|
Thylacocephala
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Ostenocaris cypriformis |
|
Osteno Outcrop.[23] |
A thylacocephalan, type member of the family Ostenocarididae inside Conchyliocarida. Originally Interpreted as a bizarre Cirriped. Ostenocaris is the most common fossil of the formation, and the main identified thylacocephalan from the formation. In the first interpretations, the genus was shown as a filter-feeding organism, which used the cephalic sac as a burrowing organ to ensure adhesion to the substrate. Based on the presence of Coprolites associated to the genus, with abundant masses of alimentary residues (hooks of cephalopods, vertebrates, remains of Crustacea) in the stomach of these organisms, Ostenocaris cypriformis was probably a necrophagous organism, and the cephalic sac can be tentatively interpreted as being a burrowing organ employed during the search for food, or as an organ of locomotion with intrinsic motility.[25] |
| |
Cephalopoda
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
Shells |
Osteno outcrop |
An ammonitidan, type member of the family Arietitidae inside Psiloceratoidea. The main ammonite identified locally. |
||
|
Shells |
Osteno outcrop |
An ammonitidan, member of the family Schlotheimiidae inside Psiloceratoidea. It was not the most abundant ammonite, but was rather common. |
||
|
Shells |
Osteno outcrop |
An ammonitidan, member of the family Arietitidae inside Psiloceratoidea. It was less common than other ammonites, although index for some locations. |
||
|
Shells |
Osteno outcrop |
An ammonitidan, member of the family Lytoceratidae inside Lytoceratina. It was not the most abundant ammonite, but was rather common. |
||
|
Several specimens with decent preservation |
Osteno outcrop |
A coleoid, type member of the family Ostenoteuthidae. A unique group of coeloids, only found at this location. Coleoids with ten arms each bearing pairs of hooks, Ostenoteuthis measure between 18 and 30 cm length.[27] |
| |
|
Shells |
Osteno outcrop |
An ammonitidan, type member of the family Oxynoticeratidae inside Ammonitida. It was not the most abundant ammonite, but was rather common. |
||
|
An incomplete specimen consisting of the arm crown only |
Osteno outcrop |
A coleoid, member of the family Ostenoteuthidae. A unique group of coeloids, only found at this location.[27] |
| |
Echinoderms
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Hispidocrinus[28] |
|
Multiple ossicles |
Pradalunga |
An Crinoidean, member of the family Isocrininae inside Isocrinida. |
|
Isocrinus[28] |
|
Multiple ossicles |
Ubiale - Clanezzo |
An Crinoidean, member of the family Isocrininae inside Isocrinida. |
|
Millericrinus[28] |
|
Multiple ossicles |
M. di Grone |
An Crinoidean, member of the family Millericrinidae inside Millericrinida. |
|
|
Multiple specimens |
Ubiale - Clanezzo |
An ophiuridan, member of the family Ophiodermatidae inside Ophiodermatina. Extant tropical species like Ophioderma are benthic predators and scavengers that show the same short spines seen in Palaeocoma.[6] |
| |
Hemichordata
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Megaderaion[29] |
Megaderaion sinemuriense |
|
Osteno Outcrop.[29] |
An acorn worm, member of the family Harrimaniidae inside Enteropneusta. It was a large sized member of its family. This genus probably lived linked to sand bottoms, where it made burrows to hide and find food.[29] |
|
Chondrichthyes
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Hybodontiformes indet |
Teeth |
Osteno Outcrop |
A shark, member of the family Hybodontiformes. |
||
Myriacanthidae[30] |
Myriacanthidae indet |
Teeth |
Osteno Outcrop |
A chimaerid, member of the family Myriacanthidae inside Chimaeriformes. |
|
Ostenoselache stenosoma |
One complete articulated specimen |
Osteno Outcrop |
An euselachiian, type member of the family Ostenoselachidae inside Elasmobranchii. A unique genus of shark, only found in the Osteno Formation. With an elongated eel-shaped morphology, the specimens found measure at least 240 mm in length, with a neurocranium with a long, complex rostrum.[16] It has been suggested it was an animal able to produce electric shocks, probably to kill prey.[16] |
| |
Palaeospinax pinnai |
A single specimen in four contiguous pieces and including parts of the dentition and squamation |
Osteno Outcrop |
A Shark, type member of the family Palaeospinacidae inside Synechodontiformes. Open water swimmer. |
||
Squaloraja sp. |
One complete articulated specimen |
Osteno Outcrop |
A chimaerid, type member of the family Squalorajidae inside Squalorajoidei. This genus belongs to a lineage of ray-like chimaeras. |
| |
Actinopterygii
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Cosmolepis ornatus |
|
Osteno Outcrop.[33] |
A primitive actinopterygiian, member of the order Palaeonisciformes. A late surviving representative of the family. |
||
Dapedium sp. |
|
Osteno Outcrop.[33] |
A primitive actinopterygiian, type member of the family Dapediidae inside Holostei. Probably a Coral Environment wanderer. |
||
Furo sp. |
|
Osteno Outcrop.[33] |
A primitive actinopterygiian, type member of the family Furidae inside Ionoscopiformes. Open water swimmer, probably forming schools. |
||
Pholidophorus bechei |
|
Osteno Outcrop.[33] |
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 sp. |
|
Osteno Outcrop.[33] |
A primitive Actinopterygiian, member of the family Pholidophoridae inside Teleostei. Open water swimmer, probably forming schools. |
||
Peripeltopleurus sp. |
|
Osteno Outcrop.[33] |
A primitive actinopterygiian, member of the family Peltopleuridae inside Neopterygii. A genus related with the Epicontinental deposition |
||
Pteroniscus sp. |
|
Osteno Outcrop.[33] |
A primitive actinopterygiian, member of the order Palaeonisciformes. A complicated genus, whose modern status is rather dubious. |
||
Sarcopterygii
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Undina (Holophagus) cf. gulo |
|
Osteno Outcrop.[33] |
A Coelacanth, member of the family Latimeriidae inside Coelacanthiformes. Isolated scales of coelacanths analogous to the genus Holophagus are quite frequent on the Osteno deposits. A series of teeth can also be identified to this genus. |
| |
Plants
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
|
Osteno Outcrop.[33] |
A coniferophytan, member of the family Cheirolepidiaceae inside Pinopsida. |
||
Equisitites bunburyanus |
|
Osteno Outcrop.[33] |
A Horsetail, member of the family Equisetaceae inside Equisetales. A freshwater-related plant, that grew as fast as modern bamboo on tropical settings. |
||
|
|
Osteno Outcrop.[33] |
A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings. |
||
Pachypteris cf. rhomboidalis |
|
Osteno Outcrop.[33] |
A tree fern, member of the family Umkomasiaceae inside Peltaspermales. Fronds of large tree ferns, related to humid ecosystems. |
||
|
|
Osteno Outcrop.[33] |
A coniferophytan, member of the family Araucariaceae inside Pinopsida. |
||
Williamsonia sp. |
|
Osteno Outcrop.[33] |
A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings. |
| |
Zamites sp. |
|
Osteno Outcrop.[33] |
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
References
- Stoppani A. (1857). Studi geologici e paleontologici sulla Lombardia. 461 pp. Tipografia Turati, Milano
- 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. PMID 15744297. S2CID 4316860.
- 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.
- 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.
- 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.
- Pinna, G. (2000). "Die Fossillagerstätte im Sinemurium (Lias) von Osteno, Italien". Europäische Fossillagerstätten, Springer, Berlin, Heidelberg. 3 (7): 91–136. doi:10.1007/978-3-642-57198-5_13. ISBN 978-3-642-62975-4. Retrieved 2 May 2023.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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. Retrieved 2 May 2023.
- 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.
- "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.
- 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.
- 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.
- 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.
- 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.
- 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. doi:10.1017/S0263593300010580. S2CID 85401617. Retrieved 2 May 2023.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.