Editing Fossil (section)

=== Replacement ===
[[File:Permineralized bryozoan.jpg|thumb|Permineralized [[bryozoan]] from the [[Devonian]] of Wisconsin]]
Replacement occurs when the shell, bone, or other tissue is replaced with another mineral. In some cases mineral replacement of the original shell occurs so gradually and at such fine scales that microstructural features are preserved despite the total loss of original material. Scientists can use such fossils when researching the anatomical structure of ancient species.<ref>{{Cite web|title=Molecular Expressions Microscopy Primer: Specialized Microscopy Techniques - Phase Contrast Photomicrography Gallery - Agatized Dinosaur Bone|url=https://micro.magnet.fsu.edu/primer/techniques/phasegallery/agatizeddinobone.html|access-date=2021-02-12|website=micro.magnet.fsu.edu}}</ref> Several species of saurids have been identified from mineralized dinosaur fossils.<ref name=natgeo>{{Cite web|date=2018-12-04|title=Exclusive: Sparkly, opal-filled fossils reveal new dinosaur species|url=https://www.nationalgeographic.com/science/2018/12/exclusive-sparkly-opal-filled-fossils-reveal-new-dinosaur-species-paleontology/|archive-url=https://web.archive.org/web/20181204142402/https://www.nationalgeographic.com/science/2018/12/exclusive-sparkly-opal-filled-fossils-reveal-new-dinosaur-species-paleontology/|url-status=dead|archive-date=December 4, 2018|access-date=2021-02-12|website=Science|language=en}}</ref><ref>{{Cite web|date=2019-06-03|title=Gem-like fossils reveal stunning new dinosaur species|url=https://www.nationalgeographic.com/science/2019/06/opal-fossils-reveal-new-species-dinosaur-australia-fostoria/|archive-url=https://web.archive.org/web/20190604033106/https://www.nationalgeographic.com/science/2019/06/opal-fossils-reveal-new-species-dinosaur-australia-fostoria/|url-status=dead|archive-date=June 4, 2019|access-date=2021-02-12|website=Science|language=en}}</ref>

==== Permineralization ====
[[Permineralization]] is a process of fossilization that occurs when an organism is buried. The empty spaces within an organism (spaces filled with liquid or gas during life) become filled with mineral-rich [[groundwater]]. Minerals precipitate from the groundwater, occupying the empty spaces. This process can occur in very small spaces, such as within the [[cell wall]] of a [[plant cell]], and can produce very detailed fossils at small scales.<ref>{{cite book |last1=Prothero |first1=Donald R. |title=Bringing fossils to life : an introduction to paleobiology |date=2013 |publisher=Columbia University Press |location=New York |isbn=978-0-231-15893-0 |page=8 |edition=Third}}</ref> For permineralization to occur, the organism must become covered by sediment soon after death, otherwise the remains are destroyed by scavengers or decomposition.{{sfn|Prothero|2013|pp=12-13}} The degree to which the remains are decayed when covered determines the later details of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of [[skin]], [[feather]]s or even soft tissues.{{sfn|Prothero|2013|p=16}} This is a form of [[diagenesis]].

====Phosphatization====
Phosphatization refers to a process of fossilization where organic matter is replaced by abundant [[calcium]]-[[phosphate]] [[mineral]]s. The produced fossils tend to be particularly dense and have a dark coloration that ranges from dark orange to black.<ref>{{Cite journal | doi = 10.1016/S0016-6995(97)80056-3 | last1 = Wilby | first1 = P. | last2 = Briggs | first2 = D. | title = Taxonomic trends in the resolution of detail preserved in fossil phosphatized soft tissues | journal = Geobios | volume = 30 | pages = 493–502 | year = 1997| bibcode = 1997Geobi..30..493W }}</ref>

====Pyritization====
This fossil preservation involves the elements [[sulfur]] and [[iron]]. Organisms may become pyritized when they are in marine sediments saturated with iron sulfides. As organic matter decays, it releases sulfide which reacts with dissolved iron in the surrounding waters, forming [[pyrite]]. Pyrite replaces carbonate shell material due to an undersaturation of carbonate in the surrounding waters.  Some plants become pyritized when they are in a clay terrain, but to a lesser extent than in a marine environment. Some pyritized fossils include [[Precambrian]] microfossils, marine [[arthropods]], and plants.<ref>Wacey, D. et al (2013) Nanoscale analysis of pyritized microfossils reveals differential heterotrophic consumption in the ~1.9-Ga Gunflint chert ''PNAS'' 110 (20) 8020-8024 {{doi| 10.1073/pnas.1221965110}}
</ref><ref>Raiswell, R. (1997). A geochemical framework for the application of stable sulfur isotopes to fossil pyritization. ''Journal of the Geological Society'' 154, 343–356.
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<gallery widths="150" heights="200">
File:Pleuroceras solare, Little Switzerland, Bavaria, Germany.jpg|Pyritized ammonoid ''[[Pleuroceras solare]]'' fossil specimen
File:Paraspirifer bownockeri.fond.jpg|Pyritized specimen of the brachiopod ''[[Paraspirifer bownockeri]]''
File:Triarthrus eatoni (pyritized fossil trilobite with appendages) (Whetstone Gulf Formation, Upper Ordovician; Lewis County, New York State, USA) 3.jpg|Pyritized ''[[Triarthrus eatoni]]'' from [[Whetstone Gulf Formation]]
File:Furcaster paleozoicus fossil brittle star (Kaub Formation, Hunsrück Slate Group, Lower Devonian; Budenbach area, western Germany) 4 (15302668235).jpg|Pyritized ''[[Furcaster paleozoicus]]'' from [[Hunsrück Slate]]
File:Tornoceras uniangulare aldenense fossil goniatite (Alden Pyrite Bed, Ludlowville Formation, Middle Devonian; western New York State, USA) 1 (15359943429).jpg|Pyritized ''[[Tornoceras uniangulare]]'' from [[Ludlowville Formation]]
</gallery>

====Silicification====
In [[silicification]], the precipitation of [[silica]] from saturated water bodies is responsible for the fossil's formation and preservation. The mineral-laden water permeates the pores and cells of some dead organism, where it becomes a [[gel]].  Over time, the gel will [[drying| dehydrate]], forming a [[silica]]-rich crystal structure, which can be expressed in the form of [[quartz]], [[chalcedony]], [[agate]], [[opal]], among others, with the shape of the original remain.<ref>Oehler, John H., & Schopf, J. William (1971). Artificial microfossils: Experimental studies of permineralization of blue-green algae in silica. ''Science''. 174, 1229–1231.</ref><ref>{{Cite journal |last1=Götz |first1=Annette E. |last2=Montenari |first2=Michael |last3=Costin |first3=Gelu |date=2017 |title=Silicification and organic matter preservation in the Anisian Muschelkalk: Implications for the basin dynamics of the central European Muschelkalk Sea |journal=Central European Geology |volume=60 |issue=1 |pages=35–52 |doi=10.1556/24.60.2017.002 |bibcode=2017CEJGl..60...35G |issn=1788-2281 |doi-access=free}}</ref>
<gallery widths="150" heights="200">
File:2017-07-15 22-10-35 (C) DxO.jpg|Chalcedony replaced fossil shells of ''[[Elimia tenera]]'' with inclusions of [[ostracods]]
File:Chalcedonized fossil gastropods (Cretaceous; possibly from Dakhla, southern Morocco) (15230327942).jpg|Chalcedonized [[gastropods]] internal molds
File:Schnecken auflicht small.jpg|Agatized internal molds of gastropods from [[Deccan Traps]]
File:Agate Chalcedony GE9323 540424.jpg|Agatized fossil coral from [[Florida]]
File:Opaleautralie.jpg|Fossil bivalves replaced by [[opal]], from [[Queensland]]
File:Addyman 3.JPG|Rear view of an opalized Addyman [[Plesiosauria|Plesiosaur]] fossil at the [[South Australian Museum]]
</gallery>