The Saltrio Formation is a geological
formation
Formation may refer to:
Linguistics
* Back-formation, the process of creating a new lexeme by removing or affixes
* Word formation, the creation of a new word by adding affixes
Mathematics and science
* Cave formation or speleothem, a secondary ...
in Italy. It dates back to the middle
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian an ...
, and would have represented a pelagic or near-epicontinental environment, judging by the presence of marine fauna such as the
nautiloid
Nautiloids are a group of marine cephalopods ( Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded speci ...
''
Cenoceras
''Cenoceras'' is an extinct genus within the cephalopod mollusc family Nautilidae, which in turn makes up part of the superfamily Nautilaceae. This genus has been described by Hyatt in 1884. The type species is ''Cenoceras intermedium'' (Sower ...
''.
[Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 532–534. .][Dal Sasso C, Maganuco S, Cau A. 2018. The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds. PeerJ 6:e5976 https://doi.org/10.7717/peerj.5976] The Fossils of the Formation were described on the late 1880s and revised on 1960s, finding first marine biota, such as Crinoids, Bivalves and other fauna related to Epicontinental basin deposits.
[Vialli, G. S. (1963). Revisione della fauna di Saltrio: i Gastropodi, i Cephalopodi dibranchiati, i Briozoi, i Brachiopodi, gli Echinodermi, i Vertebrati. Tipografia del Libro.]
Environment
Since the beginning of the jurassic, from
Hettangian
The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triassi ...
to earliest
Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian an ...
on the western
Lombardy Basin
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, ...
there was a notorious continental area that was found to be wider than previously thought, where a warm humid paleoclimate developed.
[Jadoul, Flavio, Galli, M. T., Calabrese, Lorenzo, & Gnaccolini, Mario (2005). Stratigraphy of Rhaetian to Lower Sinemurian carbonate platforms in western Lombardy (Southern Alps, Italy): paleogeographic implications. Rivista Italiana di Paleontologia e Stratigrafia, 111(2), 285-303.] The Dinosaur Fossils found on the Saltrio formation can have been translated from this area, or alternatively, the
Arbostora swell (that was located at the north of the Saltrio formation, on
Switzerland).
[Kalin, O., & DM, T. (1977).(1977): Sedimentation und Paläotektonik in den westlichen Südalpen: Zur triasisch-jurassischen Geschichte des Monte Nudo-Beckens. – Eclogae geol] This was an emerged structural high close to the ''Saltrio Formation'', that caused a division between two near subsiding basins located at Mt. Nudo (East) and Mt. Generoso (West).
[ It settled over a carbonate platform linked with other wider areas that appear along the west to the southeast, developing a large shallow water gulf to the north, where the strata deposited was controlled by a horst and tectonic gaben.][
Several outcrops of the so-called “terra rossa” paleosoils were also found, including at ]Castello Cabiaglio-Orino
Castello may refer to:
Places
*Castello, Venice, the largest of the six ''sestieri'' of Venice
*''Castello'', the old town center of Giudicato of Cagliari in Sardinia
*''Castello'', a neighbourhood in Florence
*Castello, Hong Kong, a private hous ...
, a dozen of kilometers West of Saltrio.[Wiedenmayer, F. (1963). Obere Trias bis mittlerer Lias zwischen Saltrio und Tremona:(Lombardische Alpen); d. Wechselbeziehungen zwischen Stratigraphie, Sedimentologie u. syngenet. Tektonik. na.] This outcrops show that the emerged areas that on the Hettangian-Sinemurian, the current location of the modern Maggiore Lake
Lake Maggiore (, ; it, Lago Maggiore ; lmo, label= Western Lombard, Lagh Maggior; pms, Lagh Magior; literally 'Greater Lake') or Verbano (; la, Lacus Verbanus) is a large lake located on the south side of the Alps. It is the second largest ...
were covered with forests, what was proven by the presence of large plant fragments on the Moltrasio Formation.[ The plants have been recovered between the locations of Cellina and Arolo (eastern side of Lake Maggiore), from rocks that have been found to be coeval in age to the ''Saltrio Formation''.][Lualdi, A. (1999). New data on the Western part of the M. Nudo Basin (Lower Jurassic, West Lombardy) Tubingen Geowissenschaftliche Arbeiten, Series A, 52, 173-176.] The Flora includes genera such as Bennettitales
Bennettitales (also known as cycadeoids) is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales are among the most common Mesozoic seed plants ...
(Ptilophyllum
''Ptilophyllum'' is an extinct form genus of leaves belonging to the extinct seed plant order Bennettitales. The leaves, like other Bennettitales morphogenera are generally pinnate
Pinnation (also called pennation) is the arrangement of feath ...
), terrestrial Araucariaceae
Araucariaceae – also known as araucarians – is an extremely ancient family of coniferous trees. The family achieved its maximum diversity during the Jurassic and Cretaceous periods and the early Cenozoic, when it was distributed almost world ...
(Pagiophyllum
''Pagiophyllum'' is a form genus of fossil coniferous plant foliage. Plants of the genus have been variously assigned to several different conifer groups including Araucariaceae and Cheirolepidiaceae. They were found around the globe during the ...
), and Cheirolepidiaceae
Cheirolepidiaceae is an extinct family of conifers. They first appeared in the Triassic, and were widespread during most of the Mesozoic era. They are united by the possession of a distinctive pollen type assigned to the form genus '' Classopoll ...
(Brachyphyllum
''Brachyphyllum'' (meaning "short leaf") is a form genus of fossil coniferous plant foliage. Plants of the genus have been variously assigned to several different conifer groups including Araucariaceae and Cheirolepidiaceae. They are known from ...
), that developed on inland areas with dry-warm conditions.[
The ammonites from the Saltrio Formation allow the formation to be dated to the Early ]Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian an ...
. Animals probably lived in emerged parts of carbonated platform or an area to the northwest, whose presence had never been established. In the early Sinemurian, the Arbostora swell became again a shallow open sea (ramp-slope), still surrounded South and South-West by emerged land. The dinosaur bones where washed on this period, flowed into a gulf of the Mt. Nudo basin, where they became fossilized. The latter possibility was suggested by Lualdi (1999), in which he analyzed the local geology based on the presence of terrestrial plants and terrigenous
In oceanography, terrigenous sediments are those derived from the erosion of rocks on land; that is, they are derived from ''terrestrial'' (as opposed to marine) environments. Consisting of sand, mud, and silt carried to sea by rivers, their c ...
content (sands from igneous or metamorphic rocks exposed to sub-aerial erosion) in the limestones.[ Terrestrial ]plants
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...
are essentially represented by leaves and small branches of Araucariaceans and Bennettitales
Bennettitales (also known as cycadeoids) is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales are among the most common Mesozoic seed plants ...
, the typical flora of the early Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Creta ...
. However, plants and sand (which are not abundantly referred) can be carried by wind and ocean currents. Also, according to the most current paleogeographic maps, truly continental land located closer these Jurassic times lower were the Mountains of Sardinia, Corsica, distanced many tens of kilometers WNW.[Dalla Vecchia, F.M. 2001. A new theropod dinosaur from the Lower Jurassic of Italy, Saltriosaurus. Dino Press. 3, 81-87.]
Coeval and slightly younger in age, large dinosaurs, carnivorous and herbivorous, were present as shown in various footprints of the lower Jurassic (Hettangian
The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triassi ...
-Sinemurian
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian an ...
) in the province of Trento
Trento ( or ; Ladin and lmo, Trent; german: Trient ; cim, Tria; , ), also anglicized as Trent, is a city on the Adige River in Trentino-Alto Adige/Südtirol in Italy. It is the capital of the autonomous province of Trento. In the 16th cen ...
, around east of Saltrio
Saltrio is a ''comune'' (municipality) in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerland. As of 31 December 2004, it had a population of 2,92 ...
, which changed the traditional view of the palaeoenvironments and paleogeography of the region, considered a tropical sea with small islands of the atoll
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can ...
type. Fossil footprints and tracks are preserved in tidal carbonates deposited in a relatively narrow carbonated platform in Trento, flanked to the east and west by relatively deep marine basins. Large theropods could not live in an atoll, since large areas had to be emersed to provide food and fresh water, and their herbivorous prey needed land with vegetation. The presence of vulcanodontids, cetiosaurs, primitive sauropods
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
, heterodontosaurids
Heterodontosauridae is a family of ornithischian dinosaurs that were likely among the most basal (primitive) members of the group. Their phylogenetic placement is uncertain but they are most commonly found to be primitive, outside of the group ...
, and scelidosaurs have been reported from the Calcari Grigi Group.
"''It is more likely that the Peri-Adriatic Platforms worked with temporary continental bridges that connected with Laurasia Gondwana in central Tethis, allowing migration between the two hemispheres and colonization of local coastal habitats." "During the marine transgressions, some of these lands were isolated, implicating genetic Mutations
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosi ...
in their terrestrial faunas, with typical biological consequences, as endemism and possible dwarfism''".[Cristiano Dal Sasso: Dinosaurs of Italy. In: Comptes Rendus Palevol. Bd. 2, Nr. 1, 2003.]
Invertebrate fauna
Brachiopoda
Bivalves
Gastropods
Cephalopoda
Echinoderms
Vertebrate fauna
Fish
Icthyosaurs
Pterosaurs
Dinosaurs
In 2016 new vertebrate remains were discovered in the Salnova quarry, the remains are being studied to understand if it is a new dinosaur or some other creature.
See also
* List of fossiliferous stratigraphic units in Italy
* List of dinosaur-bearing rock formations
This list of dinosaur-bearing rock formations is a list of geologic formations in which dinosaur fossils have been documented.
Containing body fossils
* List of stratigraphic units with dinosaur body fossils
** List of stratigraphic units with f ...
References
{{Reflist
Further reading
* F. M. Dalla Vecchia. 2001. Terrestrial ecosystems on the Mesozoic peri-Adriatic carbonate platforms: the vertebrate evidence. VII International Symposium on Mesozoic Terrestrial Ecosystems. Asociación Paleontología Argentina, Publicación Especial 7:77-83
Geologic formations of Italy
Jurassic System of Europe
Early Jurassic Europe
Sinemurian Stage
Limestone formations
Paleontology in Italy
Geography of Lombardy