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Chachao Formation
The Chachao Formation is a geological formation in the Mendoza Province in northern Patagonian Argentina. It is Valanginian in age and is predominantly marine, being deposited at a time of marine transgression in the Neuquén Basin, and predominantly consists of carbonate rocks. The formation belongs to the Mendoza Group, sediments deposited on the Mendoza Shelf. The formation overlies the Vaca Muerta and is overlain by the Agrio Formation. Description A typical feature of the Chachao Formation is the dominance of oysters, many of them quite large e.g. '' Aetostreon latissimun'', and others small, e.g. '' Ceratostreon minos''. Different kinds of semi-infaunal soft bottom dwellers and swimming bivalves were recognized. Additional forms are represented by gastropods, ammonites ('' Olcostephanus curacoensis''), and ichnofossils such as '' Thalassinoides sp.'' Serpulids are represented by the colonial ''Sarcinella sp.'', and the solitary form '' Parsimonia sp.'' The highly div ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretaceous and precedes the Hauterivian Stage of the Lower Cretaceous. Stratigraphic definitions The Valanginian was first described and named by Édouard Desor in 1853. It is named after Valangin Valangin () is a former municipality in the district of Val-de-Ruz in the canton of Neuchâtel in Switzerland. On 1 January 2021 the former municipalities of Corcelles-Cormondrèche, Peseux and Valangin merged into the municipality of Neuchâ ..., a small town north of Neuchâtel in the Jura Mountains of Switzerland. The base of the Valanginian is at the first appearance of Calpionellidae, calpionellid species ''Calpionellites darderi'' in the stratigraphic column. A global reference section (a GSSP) had in 2009 not yet been appointed. The top o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polychaeta
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm (''Arenicola marina'') and the sandworm or clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans. Only 168 species (less than 2% of all polychaetes) are known from f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olcostephanus
''Olcostephanus'' is an extinct ammonoid cephalopod genus belonging to the family Olcostephanidae. These fast-moving nektonic carnivores lived during the Cretaceous, from the upper Valanginian to the lower Hauterivian age.Sepkoski, JacSepkoski's Online Genus Database – Cephalopoda/ref> in '''', Part L (Roger L. Kaesler ''et al.'' eds.), Boulder, Colorado: The Geological Society of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
