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Pisidium Scutulatum
''Pisidium'' is a genus of very small or minute freshwater clams known as pill clams or pea clams, aquatic bivalve molluscs in the family Sphaeriidae, the pea clams and fingernail clams. In some bivalve classification systems, the family Sphaeriidae is referred to as Pisidiidae, and occasionally ''Pisidium'' species are grouped in a subfamily known as Pisidiinae. ''Pisidium'' and taphonomy In large enough quantities, the minute shells of these bivalves can affect environmental conditions, and this change in conditions can positively affect the ability of organic remains in the immediate environment to fossilize (one aspect of taphonomy). For example, in the Dinosaur Park Formation, the fossil remains of hadrosaur eggshells are rare. This is because the breakdown of tannins from the local coniferous Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valve (mollusc)
A valve is each articulating part of the shell of a mollusc or another multi-shelled animal such as brachiopods and some crustaceans. Each part is known as a valve or in the case of chitons, a "plate". Members of two classes of molluscs, the Bivalvia (clams) and the Polyplacophora (chitons), have valves. Species within one family of very unusual small sea snails, marine opisthobranch gastropods in the family Juliidae, also have two articulating shells or valves, which resemble those of a bivalve. This exceptional family is commonly known as the bivalved gastropods. Gastropods in general are sometimes called "univalves", because in those that have a shell, the shell is usually in one part. Chitons The valves of chitons are eight dorsal, articulated shell plates, which are frequently coloured and sculpted. After death the girdle that holds the plates together disintegrates and the plates separate. Thus individual plates can be found washed up in beach drift, as shown in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
