How Do Paleontologists Excavate Fossils?
The main job of a paleontologist is to study ancient life. Because most ancient organisms have gone extinct or changed greatly since they first evolved millions of years ago, paleontologists use fossils to decipher clues of the ancient past. Clues found in both the excavation site and the lab will reveal a lot about a once-living organism.
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Fossilization
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Fossilization is most likely to occur when an organism dies in a body of water or falls into a body of water shortly after death. The water insulates the organism from total deterioration, and over time what remains becomes trapped beneath large mounds of sediment. Many things can be revealed about an organism from its fossil or the area in which it was buried: its bone structure, environment, lifestyle, age and possibly the internal composition, although soft tissue usually does not fossilize.
Fossil Location
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Because the fossil layer is often preserved intact by the actual order of fossilization, this gives paleontologists a powerful clue about where to look for specific fossils. The Stegosaurus, for instance, is likely to be found in the late Jurassic period. Knowing the habitat of a specific organism may also help paleontologists search locations that once contained the corresponding environment. Because the evidence can often be spotty, paleontologists must sometimes extrapolate from what we do know. Occasionally a fossil may stick out of the surface of a rock or be found by builders or diggers, which obviates the need for paleontologists to do the searching.
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Excavation
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When paleontologists do find a fossil, they often mark its position in the rock. To initially expose the fossil, broad chunks of rock are taken out with picks or drills. Within a few inches, more subtle tools like chisels, trowels, hammers, whisks and dental drills are used. Larger fossils often require bigger tools, however. Some fossils, especially if they are more fragile, may be removed while they are still partially encased within the rock. Fossils are extensively measured and photographed before being sent away.
Other Methods
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Sometimes it is necessary to employ special techniques to remove a fossil from the rock. Dilute acid can be used to dissolve limestone rock away if the fossil itself does not dissolve within the acid. Fossils embedded in particularly soft rock can be washed through a sieve, which has a perforated bottom that can collect the fossil but remove the dissolved rock and water.
Laboratory
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In the laboratory, whatever excess rock remaining may now be removed using hammers, chisels, drills and rock saws. If the specimen is small, the rocks are chipped away underneath a microscope. Glue can be used to repair any breakage or strengthen fossils, which can also be applied at the excavation site before the fossil is stressed by its removal and sent away.
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References
- Photo Credit fischfossil image by Falk from Fotolia.com
