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Mollusc Classes
Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The number of additional fossil species is estimated between 60,000 and 100,000, and the proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat, as numerous groups are freshwater and even terrestrial species. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known extant invertebrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terreneuvian
The Terreneuvian is the lowermost and oldest Series (stratigraphy), series of the Cambrian geological System (stratigraphy), system. Its base is defined by the first appearance datum of the trace fossil ''Treptichnus pedum'' around million years ago. Its top is defined as the first appearance of trilobites in the stratigraphic record around million years ago. This series' name was formally accepted by the International Commission on Stratigraphy in 2007. The Fortunian Stage (stratigraphy), stage and presently unnamed Cambrian Cambrian Stage 2, Stage 2 are the stages within this series. The Terreneuvian corresponds to the pre-trilobite, trilobitic Cambrian. The name Terreneuvian is derived from ''Terre Neuve'', the French name for the island of Newfoundland (island), Newfoundland, Canada, where many rocks of this age are found, including the type section. GSSP The type locality (Global Boundary Stratotype Section and Point, GSSP) of the Terreneuvian is in Fortune Head, at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
