Fossil dealers

Fossil collecting (some times, in a non-scientific sense, fossil hunting) is the collection of fossils for scientific study, hobby, or profit. Fossil collecting, as practiced by amateurs, is the predecessor of modern paleontology and many still collect fossils and study fossils as amateurs. Professionals and amateurs alike collect fossils for their scientific value. A commercial trade in fossils has also long existed, with some of this being practised illegally.

Fossils are generally found in sedimentary rock with differentiated strata representing a succession of deposited material. The occurrence of fossil bearing material depends on environmental factors before and after the time of preservation. After death, the first preserving factor is a rapid burial in water bodies or terrestrial sediment which would help in preserving the specimen. These rocks types are usually termed clastic rock, and are further subdivided into fine, medium and coarse grained material. While fossils can be found in all grain types, more detailed specimens are found in the fine grained material. A second type of burial is the non-clastic rock, form where the rock is made up of the precipitation of compacted fossil material, types of rock include limestone and coal. The third fossil bearing material is the evaporates, which precipitate out of concentrated dissolved salts to form nodular deposits, examples include rock salt and phosphate concentrations. The evaporates are usually associated with gastropod, algae, vertebrate, and trace fossils. Fossils are not to be found in areas of igneous rock (except in some beds between lava flows). In rocks which have undergone metamorphism, fossils are generally so distorted that they are difficult to recognize or have been destroyed completely.

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Wikipedia