http://www.enchantedlearning.com/subjec ... ilhow.html
* The fossil has the same shape as the original object, but is chemically more like a rock! Some of the original hydroxy-apatite (a major bone consitiuent) remains, although it is saturated with silica (rock).
* There are six ways that organisms can turn into fossils, including:
-1* unaltered preservation (like insects or plant parts trapped in amber, a hardened form of tree sap)
-2* permineralization=petrification (in which rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil - can preserve hard and soft parts - most bone and wood fossils are permineralized)
-3* replacement (An organism's hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite, or iron)
-4* carbonization=coalification (in which only the carbon remains in the specimen - other elements, like hydrogen, oxygen, and nitrogen are removed)
-5* recrystalization (hard parts either revert to more stable minerals or small crystals turn into larger crystals)
-6* authigenic preservation (molds and casts of organisms that have been destroyed or dissolved).
* This, however, is another possible means of fossilization in a short time.
* This is just kind of interesting.After some experimentation, the researchers found a way to overcome a dead bird's buoyancy. When a carcass was dropped onto moist sediments that contained clay, the material soaked into the bird's feathers and bound the body to the mud in just a few minutes. Later, when water was added to the tank, the stuck-in-the-mud carcass remained submerged. 5
* Taking their work even further, Krauss and his team added enough sediment to the tanks to bury the submerged carcasses. Then, they placed weights on the mud to increase the pressure, as a naturally buried body would experience if accumulating lake sediments gradually covered it. The team left the bodies in place for 3 years.
* When the researchers unearthed their samples, they found that the patterns and extent of preservation of the faux-fossil birds were remarkably similar to those seen in actual fossils millions of years old. This resemblance suggests that the remains of ancient birds might have begun their process of fossilization in just such a way, Krauss notes. The team's findings may enable scientists to better interpret fossils and deduce the environments in which they formed, he adds. 6
* You’ve probably read creationist claims of hats or fence posts that fossilized in just a few years. Creationists generally claim that the proper conditions, not long periods of time, are all that are needed for fossilization. That’s what Briggs’ experiment showed. Briggs doesn’t know exactly what the proper conditions are, but some eggs mineralized, and some didn’t, despite being buried for the same amount of time. Furthermore, the durations of the tests were very short, geologically speaking. It took just weeks or months for the process to begin. If they had more patience, they would have seen more mineralization (in those situations where the conditions were favorable).
* Some clamshell fossils contain up to a hundred fish fossils inside.