Calcare di Sogno

The Calcare di Sogno ("Sogno Limestone"; also known as the Sogno Formation) is a geological formation in Italy, dated to roughly between 183-181 million years ago and covering the Toarcian stages of the Jurassic Period in the Mesozoic Era.[1] Thallatosuchian remains are known from the formation.

Calcare di Sogno Stratigraphic range: Toarcian ~183–181 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Formazione delle Radiolariti
Overlies	Calcare di Domaro, Calcare di Morbio, Unnamed limestones[note 1]
Thickness	Typically 120–140 m (390–460 ft) East and west 70–100 m (230–330 ft)
Lithology
Primary	Marl, marly limestone & abundance of clay Secondary: Alternation of marly limestones and marls, presence of graded Chalcudites
Other	Limestones with nodules of flint & subordinate marls
Location
Coordinates	45.8°N 9.3°E / 45.8; 9.3
Approximate paleocoordinates	33.4°N 18.9°E / 33.4; 18.9
Region	Lecco Province
Country	Italy
Type section
Named for	Sogno
Named by	Gaetani & Poliani
Calcare di Sogno (Italy) Show map of Italy Calcare di Sogno (Lombardy) Show map of Lombardy

Description

Early-Mid Jurassic (170 Ma)

The formation is characterized by a disposition of regional deposition equivalent to the German Posidonia Shale, with a benthonic setting and deposition trends, mostly populated by marine fauna.[2] The environment of the formation was related to a marginal marine deposit, with probably epicontinetal deposition from near land environments, being connected to the central European seas of the Toarcian.[3][4][5]

Fossil content

Flora

Several plant leaves and fragments of wood wheren´t identified.[6]

Genus	Species	Stratigraphic position	Material	Notes	Images
Ginkgo[6]	Ginkgo digitata	Mount Brughetto Mount Cornizzolo	Leaves	Affinities with the Ginkgoaceae. Arboreal plants related to the modern Ginkgo species.
Pagiophyllum[6]	Pagiophyllum kurri Pagiophyllum rotzoanum	Mount Brughetto Mount Cornizzolo	Leaves	Affinities with the Araucariaceae. Arbustive to arboreal plants with several leaf morphotypes, probably from nearshore environments.

Molluscs

Genus	Species	Stratigraphic position	Material	Notes	Images
Hildaites[1][2]	Hildaites sp.	Mount Brughetto Mount Cornizzolo	Especimens	A Hildoceratidae ammonite
Cornaptychus[1][2]	Cornaptychus lythensis	Mount Brughetto Mount Cornizzolo	Especimens	An indeterminate ammonite. Some of the specimens found are very fragmentary, making its identification complex.[2]
Dactylioceras[1][2]	Dactylioceras polymorphus	Mount Brughetto Mount Cornizzolo	Especimens	Type member Dactylioceratinae family of Ammonites. A common mediterranean genera, found on deposits along all europe.
Mesodactylites[1][2]	Mesodactylites sapphicus Mesodactylites sp.	Mount Brughetto Mount Cornizzolo	Especimens	A Nodicoeloceratinae ammonite
Harpoceras[1][2]	Harpoceras sp.	Mount Brughetto Mount Cornizzolo	Especimens	Type reprensentative genus of the Harpoceratinae ammonite family
Collina[1][2]	Collina gemma	Mount Brughetto Mount Cornizzolo	Especimens	A Dactylioceratidae ammonite. Present and abundant on the Mediterranean Toarcian realm.

Arthropods

Genus	Species	Stratigraphic position	Material	Notes	Images
Proeryon[1][7]	Proeryon hartmanni	Mount Brughetto Mount Cornizzolo	Various specimens	A Erymidae Decapodan Crustacean common on the mediterranean rocks. Frequent presence of Burrows Thalassinoides with fossilised specimens nearby. A complete Seafloor section was fossilized.
Gabaleryon[8]	Gabaleryon garassinoi	Mount Brughetto Mount Cornizzolo	Various specimens	A Coleiidae Decapodan. Was confussed with Proeryon hartmanni specimens.
?Antrimpos[8]	?Antrimpos sp.	Mount Cornizzolo	Single specimen	A Penaeidae Decapodan.
?Etallonia[8]	?Etallonia sp.	Mount Cornizzolo	Single specimen	An Axiidae Decapodan.
Archaeopalinurus[7]	Archaeopalinurus cfr. A. levis	Mount Brughetto Mount Cornizzolo	Various specimens	A Palinuroidean Decapodan.
Uncina[9]	Uncina alpina	Mount Brughetto Mount Cornizzolo	Various Specimens	An Astacidean Decapodan of the family Uncinidae. A large decapodan, with sizes up to 40 cm.

Fish

Genus	Species	Stratigraphic position	Material	Notes	Images
Pholidophorus [6][10]	Pholidophorus sp.	Monte Cornizzolo	Several Especimens	Type member of the family Pholidophoridae inside Pachycormiformes. A small sized fish, mostly related to marine deposits, associated with various predatory behaviours, including coeloids and Crocodrylomorphs.
Leptolepis[6][10]	Leptolepis coryphaenoides Leptolepis sp.	Monte Cornizzolo	+100 specimens	Type member of the family Leptolepidae inside Leptolepiformes. It is the most abundant fish found on the formation.
Pachycormus[6][10]	Pachycormus sp.	Monte Cornizzolo	Several Especimens	The main member of the family Pachycormidae inside Pachycormiformes. Large sized fish, able to reach near 1.4 m long.

Crocodyliformes

Genus	Species	Location	Material	Notes	Images
cf.Pelagosaurus[10]	cf. Pelagosaurus sp.	Monte Cornizzolo	Various specimens MSNM V4012, MSNM V4013.	A Thalattosuchian marine crocodrylomorph of the family Teleosauridae.The specimens found where of small size, with several characters such as opened neurocentral vertebral sutures and non sutured caudal pleurapophyses, that led to expeculate a possible juvenile or subadult status.

See also

• List of fossiliferous stratigraphic units in Italy
• Toarcian turnover
• Toarcian formations
  • Marne di Monte Serrone, Italy
  • Sachrang Formation, Austria
  • Posidonia Shale, Lagerstätte in Germany
  • Irlbach Sandstone, Germany
  • Ciechocinek Formation, Germany and Poland
  • Krempachy Marl Formation, Poland and Slovakia
  • Lava Formation, Lithuania
  • Azilal Group, North Africa
  • Whitby Mudstone, England
  • Fernie Formation, Alberta and British Columbia
    • Poker Chip Shale
  • Whiteaves Formation, British Columbia
  • Navajo Sandstone, Utah
  • Los Molles Formation, Argentina
  • Mawson Formation, Antarctica
  • Kandreho Formation, Madagascar
  • Kota Formation, India
  • Cattamarra Coal Measures, Australia

Notes and references

Notes

1. Bioturbed hazel-gray limestones in planar layers of about 20 cm, with concentration of gray flint and gray & reddish marls, along with calcareous marl.[1]

References

1. CARTA GEOLOGICA D’ITALIA 1:50.000 - CATALOGO DELLE FORMAZIONE. Formazione di Sogno.SERVIZIO GEOLOGICO - CONSIGLIO NAZIONALE DELLE RICERCHE - COMMISSIONE ITALIANA DI STRATIGRAFIA: http://www.isprambiente.gov.it/files/pubblicazioni/periodicitecnici/quaderni-sgi/quad7/form5.pdf
2. GAETANI M. & POLIANI G. (1978) - Il Toarciano ed il Giurassico medio in Albenza (Bergamo). Riv. It. Pal. Strat., 84 (2): 349-382, 5 figg., 2 tavv., Milano.
3. GAETANI M. & ERBA E. (1990) - Il Bacino Lombardo: un sistema paleo alto/fossa in un margine continentale passivo durante il Giurassico. In: JADOUL F. & MASSIOTTA P. (Eds.): «La geologia italiana degli anni ’90 - Guida alle escursioni pre-congresso». 75° Congr. Naz. Soc. Geol. It.: Escursione A3, pp. 23, 14 figg., 1 tav., Milano
4. DEL SERE M. (1966) - «Lagenidea» del Lias dell’Albenza (Bergamo). Riv. It. Pal. Strat., 72 (1): 147-188, 2 figg.,4 tavv., Milano.
5. BERSEZIO R., JADOUL F. & CHINAGLIA N. (1997) - Geological map of the Norian-Jurassic succession of Southern Alps north of Bergamo: explanatory notes. Boll. Soc. Geol. It., 116 (2): 363-378, 1 carta geol., Roma
6. A. Tintori. 1977. Toarcian fishes from the Lombardian basin. Bolletino della Società Paleontologica Italiana 16:143-152
7. Garassino, A., & Gironi, B. (2005). Proeryon hartmanni (v. Meyer, 1835)(Crustacea, Decapoda, Eryonoidea) and Archaeopalinurus cfr. A. levis Pinna, 1974 (Crustacea, Decapoda, Palinuroidea) from the Lower Jurassic (Toarcian) of Cesana Brianza-Suello (Lecco, N Italy). Atti della Società italiana di Scienze naturali e del Museo civico di Storia naturale in Milano, 146(1), 53-68.
8. Audo, D., Williams, M., Charbonnier, S., & Schweigert, G. (2017). Gabaleryon, a new genus of widespread early Toarcian polychelidan lobsters. Journal of Systematic Palaeontology, 15(3), 205-222.
9. Schweigert, G., Garassino, A., Hall, R. L., Hauff, R. B. & Karasawa, H. 2003. The lobster genus Uncina Quenstedt, 1851 (Crustacea: Decapoda: Astacidea: Uncinidae) from the Lower Jurassic. Stuttgarter Beiträge zur Naturkunde, Serie B, 332, 1-43
10. M. Delfino and C. Dal Sasso. 2006. Marine reptiles (Thalattosuchia) from the Early Jurassic of Lombardy (northern Italy). Geobios 39:346-354

Bibliography

• Weishampel, David B.; Peter Dodson, and Halszka Osmólska (eds.). 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21. ISBN 0-520-24209-2