Soft tissue preservation

{{hatnote|Not to be confused with [[Living fossil]]s.}}
{{Sciencenav}}
'''Soft tissue preservation''' is when, during the process of [[fossil]]isation, soft tissues are preserved. For various reasons, soft tissues (i.e. non-bones) do not ''usually'' survive in fossils, but it does happen from time to time.

==Varieties==
This can happen in a number of different ways:

===Mineralised tissue===
Normally, fossils become fossils&mdash;and not just a pile of bones in the ground &mdash; via a process called mineralisation. This is when the material that makes up the corpse<ref>Or plant material, but [[Botany|who cares about them]]?</ref> is chemically altered and becomes non-organic.

In most cases [[bacteria]] get to the fossil before this process takes place, stripping the meat from the bone. Consequentially, the norm is for only the bones to be preserved.

However, in some circumstances the soft tissues will ''also'' be mineralised. The fact that this is still referred to as 'soft tissue preservation' confuses people to no end.

===Traces, residues and impressions===
[[File:Microraptor gui holotype.png|thumb|right|300px|The arrows on this picture of the original ''Microraptor'' specimen conveniently point out traces of feathers. [[Argument from design#Argument from fine tuning|What are the odds]]?]]
Sometimes &mdash; rather than being preserved as above &mdash; tissue such as skin or feathers may leave impressions or other traces in the rock. Many [[dinosaurs]] are known to have had feathers because of this kind of preservation: we know, for example that ''{{wpl|Velociraptor}}'' and ''{{wpl|Deinonychus}}'' did because of the discovery of quill knobs in fossils.<ref>[http://www.sciencemag.org/content/317/5845/1721 Feather Quill Knobs in the Dinosaur ''Velociraptor'']</ref>

Also fitting under this category are tiny residues of [[proteins]] and other organic molecules surviving the millennia in sheltered cracks in bones, etc.

===Not-all-that-soft tissue===
Considering that the simplest definition of "soft tissue" is "organic material that isn't bone", there's an awful lot covered by the term that doesn't really belong in the same category as muscle fibres, for example. The polysaccharide known as chitin is one such 'hard' soft tissue &mdash; it is what makes up the exoskeletons of [[crustaceans]] and [[insects]], and the [[cell]] walls of [[fungus|fungi]].

It should come as no surprise that, like bone, chitin can and will mineralise and fossilise. However, it also has the potential of simply surviving &mdash; in certain circumstances, like the residues above &mdash; the millions of years required to be discovered by [[Paleontology|paleontologists]]. One of the oldest discovered examples of chitin preservation was of a 34.36 million year-old cuttlefish,<ref>{{oa}} [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028195 Characterization of Organics Consistent with β-Chitin Preserved in the Late Eocene Cuttlefish ''Mississaepia mississippiensis'']</ref> the latching on to which by a group of [[Young Earth creationism|young-Earth creationists]] naturally incurred the wrath of [[PZ Myers]].<ref>[http://www.icr.org/article/6509/ Fossil Cuttlefish Has Original Tissue] and [http://www.icr.org/article/6511/ Evolution Can't Explain Organic Fossils], ''[[Institute for Creation Research#Daily Science Updates|ICR News]]''.</ref><ref>[http://freethoughtblogs.com/pharyngula/2011/12/15/creationist-abuse-of-cuttlefish-chitin/ Creationist abuse of cuttlefish chitin]</ref>

===Organic tissue===
[[File:Gecko legs in amber.jpg|thumb|right|Gecko legs in amber]]
On rare occasion, as alluded to in the above categories, organic tissue will survive unchanged by the millennia. However, as a general rule, this becomes even rarer as time goes on since the organism died. Common mechanisms include freezing in glaciers and permafrost, preservation in amber, burial in anaerobic conditions, and general inaccessibility to [[bacteria|microbes]].<ref>This is, understandably, quite hard to do.</ref>

Organic molecules&mdash;if left undisturbed for thousands if not millions of years&mdash;are believed to spontaneously degrade into their component, smaller molecules.<ref>Note that these may ''still'' be classed as organic.</ref> However, there is little consensus within the scientific community as to how long this takes. In many cases, traces of organic tissue have been discovered in fossils many millions of years older than the upper limit allowed for by lab experiments. You can see where this is going, can't you?

==Creationist claims==
This apparent impossibility is repeatedly seized upon by [[creationists]] to "prove" the young [[Earth]]. There are a number of more notable incidences of this, but one will note that should a fortnight go by without a creationist news outlet trumpeting some study or another on this subject we will know that we have won the [[culture war]]s.

The common thread in this claim is the great irony of creationists [[dogma]]tically adhering to the results of lab studies using [[uniformitarian]] preconceptions of processes lasting millions of years which [[How do you know? Were you there?|nobody has directly observed]].

===The Schweitzer fossils===
[[File:Tyrannosaurus peptides.jpg|thumb|right|''T. rex'' femur (MOR 1125) from which demineralized matrix (insets; bars, 20 µm) and peptides were obtained]]
{{cquote|They treat you really bad, they twist your words and they manipulate your data.|||Dr. Mary Schweitzer, on creationists abusing her work.<ref name="DS">[http://www.smithsonianmag.com/science-nature/dinosaur.html Dinosaur Shocker]</ref>}}

The work of [[Theistic evolution|non-creationist]] [[Christian]]<ref name="DS"/> palaeontologist Mary Higby Schweitzer has become a magnet for creationists.

Her first appearance above the parapet came in 1993, claiming the discovery of collagen in a ''T. rex'' fossilized bone dated at 68 million years old. Arguments about whether or not the discovery is the genuine article has raged within the scientific community ever since,<ref>{{oa}} [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020381 Dinosaur Peptides Suggest Mechanisms of Protein Survival]</ref> Dr. Schweitzer for her part having supported her case with her discovery of a second tissue-containing bone in the meantime.<ref>[http://www.sciencemag.org/content/307/5717/1952.abstract Soft-Tissue Vessels and Cellular Preservation in ''Tyrannosaurus rex'']</ref> The creationists, of course, have picked up on it without qualms.<ref>[http://www.icr.org/article/6220/ Just one example].</ref>

===Published Reports of Original Soft Tissue Fossils===
In July of 2011 [[Brian Thomas]] compiled for the [[Institute for Creation Research]] a list of "Published Reports of Original Soft Tissue Fossils."<ref>[http://www.icr.org/soft-tissue-list/ Published Reports of Original Soft Tissue Fossils]</ref> He found 38 examples of "Articles Published in Peer-Reviewed Journals"<ref>''Real'' peer reviewed journals… most of them.</ref> and 4 "Preliminary Reports Published Elsewhere" (known to the rest of the world as newspaper articles/science by press release).

==See also==
*[[101 evidences for a young age of the Earth and the universe]]
*[[Age of the Earth]]
*[[Branches of science you have to ignore to believe in young Earth creationism]]
*[[Evidence against a recent creation]]
*[[PRATT]]

==References==
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[[Category:Science]]
[[Category:Creationism]]
[[Category:Paleontology]]

Categories: Science, Creationism, Paleontology