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 | |
Thickness | 200 m |
Lithology | |
Primary | Limestone |
Location | |
Coordinates | 46°00′N9°06′E / 46.0°N 9.1°E |
Approximate paleocoordinates | 33°12′N15°36′E / 33.2°N 15.6°E |
Region | Lombardy |
Country | |
Type section | |
Named for | Moltrasio |
Named by | Antonio Stoppani [1] |
Year defined | 1857 |
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]
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]
Genus | Species | Material | Location | Notes | Images |
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|
| Osteno Outcrop | 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] | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| Osteno Outcrop | A polychaete, member of the group Phyllodocemorpha with incertae sedis assignation. This polychaete was probably an open swimmer more than a substrate dweller. [11] | ||
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] |
| 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] | ||
| 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] |
| Various specimens fairly preserved | Osteno Outcrop | A decapod belonging to the family Polychelidae | |
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| Osteno Outcrop | 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] | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| Osteno Outcrop | 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] | ||
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] | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
| Multiple ossicles | Pradalunga | An Crinoidean, member of the family Isocrininae inside Isocrinida. | ||
| Multiple ossicles | Ubiale - Clanezzo | An Crinoidean, member of the family Isocrininae inside Isocrinida. | ||
| 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] | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| Osteno Outcrop | 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] | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
Indeterminate | Teeth | Osteno Outcrop | A shark, member of the family Hybodontiformes. | ||
Gen et sp. nov | Virtually complete skull with associated parts of the branchial skeleton | Osteno Outcrop | A chimaerid, member of the family Myriacanthidae inside Chimaeriformes. | ||
| 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] | ||
| 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. | ||
| 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. | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| 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. [35] | ||
|
| Osteno Outcrop | A primitive actinopterygiian, type member of the family Dapediidae inside Holostei. Probably a Coral Environment wanderer. | ||
|
| Osteno Outcrop | A primitive actinopterygiian, type member of the family Furidae inside Ionoscopiformes. An enlongated Gar-alike taxon. | ||
|
| 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. | ||
|
| Osteno Outcrop | A primitive Actinopterygiian, member of the family Pholidophoridae inside Teleostei. Open water swimmer, probably forming schools. | ||
|
| 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. [37] | ||
|
| Osteno Outcrop | A primitive actinopterygiian, member of the family Peltopleuridae inside Neopterygii. Probably represents the only known Jurassic survivor of the order Peltopleuriformes | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
|
| Osteno Outcrop | A Coelacanth, member of the family Latimeriidae inside Coelacanthiformes. Isolated 20 mm scales of coelacanths analogous to the genus Holophagus are quite frequent on the Osteno deposits, suggesting a taxon up to 75 cm long. | ||
Genus | Species | Material | Location | Notes | Images |
---|---|---|---|---|---|
| Branched Shoots |
| A coniferophytan, member of the family Cheirolepidiaceae inside Pinopsida. | ||
Clathropteris [40] |
| Fronds |
| A Fern, member of the family Dipteridaceae | |
Ctenopteris [40] |
| Fronds |
| A Fern, member of the family Polypodiaceae | |
| Stems |
| A Horsetail, member of the family Equisetaceae inside Equisetales. A freshwater-related plant, that grew as fast as modern bamboo on tropical settings. | ||
Lomatopteris [40] |
| Fronds |
| A "Seed Fern", Affinities with Cyclopteridaceae inside Pteridospermatophyta. | |
| Leaflets |
| A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings. | ||
| Fronds |
| A "Seed Fern", member of the family Corystospermaceae inside Corystospermales. | ||
| Branched Shoots |
| A coniferophytan, member of the family Araucariaceae inside Pinopsida. | ||
Thinnfeldia [40] |
| Fronds |
| A "Seed Fern", member of the family Corystospermaceae inside Corystospermales. | |
| Reproductive Organ |
| A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings. | ||
Widdringtonites [40] |
| Branched Shoots |
| A coniferophytan, member of the family Araucariaceae or Cupressaceae inside Pinopsida. | |
| Leaflets |
| A spermatopsidan, member of the family Bennettitales inside Bennettitopsida. Cycad-like flora, common on dry settings. | ||
Carlo Alzona was an Italian medical doctor, an entomologist and a malacologist. He was born on 26 May 1881 in Turin. He was the director of the Muséum de Genoa from 1947 to 1955. He specialised in Coleoptera. Alzona died on 14 May 1961 in Genoa.
The Thylacocephala are group of extinct probable mandibulate arthropods, that have been considered by some researchers as having possible crustacean affinities. As a class they have a short research history, having been erected in the early 1980s.
The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic. The use of the term "Isalo III" is somewhat controversial as the two prior units Isalo I and II are Triassic cross-bedded sandstone units that form a continuous depositional sequence, while the "Isalo III" sandstones are not part of the same depositional sequence, and were deposited considerably later. and are perhaps better treated as part of several separate formations. It is traditionally divided into two subunits the lower, Bajocian aged Isalo IIIa unit also known as the Beronono Formation and the upper, Bathonian aged Isalo IIIb unit also known as the Sakaraha Formation or Sakahara Formation. The Sakaraha Formation consists of sandstones, marls and carbonates and represents a coastal plain environment, and is laterally equivalent to the predominantly carbonate Bemaraha Formation, which represents a coastal barrier lagoon complex. The formation is found in the northwest and in the southeast of the country and has provided a variety of fossils.
The Forni Dolostone, also known as the Dolomia di Forni, is a Late Triassic dolomite geological formation in northeastern Italy. The formation was deposited in a lagoonal to shallow marine environment.
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus Hexapus, and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of Stevea williamsi, from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa.
Eubrachyura is a group of decapod crustaceans comprising the more derived crabs. It is divided into two subsections, based on the position of the genital openings in the two sexes. In the Heterotremata, the openings are on the legs in the males, but on the sternum in females, while in the Thoracotremata, the openings are on the sternum in both sexes. This contrasts with the situation in other decapods, in which the genital openings are always on the legs. Heterotremata is the larger of the two groups, containing the species-rich superfamilies Xanthoidea and Pilumnoidea and all the freshwater crabs. The eubrachyura is well known for actively and constantly building its own burrows. The fossil record of the Eubrachyura extends back to the Cretaceous; the supposed Bathonian representative of the group, Hebertides jurassica, ultimately turned out to be Cenozoic in age.
Corystidae is a family of crabs, in its own superfamily, Corystoidea. It includes what was once thought to be the oldest Eubrachyuran fossil, Hebertides jurassica, thought to be dating from the Bathonian ; the species was subsequently reinterpreted as being Cenozoic in age. Corystidae contains ten extant and five extinct species in eight genera:
Scyllarides is a genus of slipper lobsters.
Ambilobeia is an extinct genus of prawn which existed in Ambilobé, Madagascar during the Olenekian stage of the Early Triassic period. It contains the species Ambilobeia karojoi.
Cretapenaeus berberus is an extinct species of prawn which existed in Morocco during the Late Cretaceous period. It is the only species in the genus Cretapenaeus.
Cretasergestes sahelalmaensis is an extinct species of prawn which existed in Lebanon during the Late Cretaceous period, the only species in the genus Cretasergestes.
Longitergite is an extinct genus of prawn which existed in Russia during the Lower Miocene period. It contains a single species.
Pseudobombur is an extinct genus of crustacean in the order Decapoda, containing the species Pseudobombur nummuliticus.
Enantiophoenix is a genus of enantiornithine birds. Fossil remains were recovered from Lebanon. Lumps of amber preserved with one specimen indicate it may have fed on tree sap.
Eophasma is a genus of fossil nematodes from the Jurassic of Osteno in Lombardy, Italy. It has only one species, Eophasma jurasicum.
Bruno Parisi was an Italian zoologist and museum director. His main research field were the crustaceans (Crustacea). From 1928 to 1951 he was director of the Museo Civico di Storia Naturale di Milano.
Napoleone Pini was an Italian zoologist and palaeontologist.
Ostenocaris is a Jurassic species of giant Thylacocephalan crustacean, sufficiently distinct from its relatives to be placed in its own family, Ostenocarididae. It is believed to be a bethonic animal and one of the most important necrophagous animals of its environment. Originally Interpreted as a bizarre barnacle. 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 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. Later studies agree that cephalic sac is actually extremely large compound eyes.
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