What percent of original material is actually preserved in fossils?

[Somethingwicked]

So, I know fossils are largely replaced by minerals which turn them to stone in the shape of the original (bone, tooth, whatever). But do some minerals survive? For instance, does the original calcium in the tooth or bone remain?

 

What percent of a fossil would you guess is original mineral vs replaced mineral?

[Darktooth]

Short answer: There is no clear cut answer to this. It would depend on many different variables. Age, location, type of fossil, etc... 

[Top Trilo]

Ya I agree with what darktooth said there are no two fossils exactly alike, the same species could fossilize differently just based on location. And the fossilization process favors some types over others like ammonite, not so much octopi because they have no hard parts. So it just depends on the fossil.

[Norki]

There are some original organic materials that can be found in certain fossils, especially ones composed mostly of rock minerals like calcium. Some examples include aragonite and tooth enamel.

 

(I've also learned recently that certain plant compounds like cellulose can also be preserved in fossils)...

[aplomado]

Darktooth is right.

 

Fossils are traces or remains of ancient life, no matter how they are preserved.  There are many types of fossils.

 

I suspect some fossils, like amber, carry large amounts of the original material.

[FranzBernhard]

On 27.11.2020 at 8:33 PM, Somethingwicked said:

For instance, does the original calcium in the tooth or bone remain?

To answer this particular question:

It depends also here on the circumstances. But it seems, that in some cases, the calcium atoms nowadays sitting in the shell are still mostly the same as in the shell during the life time of the creature.

Because sometimes it is possible to determine the age of shells via Sr-isotopes. These shells can be up to 100 Million years old (maybe older, don´t know) and still give consistent Sr isotope ratios, attributable to a meaningful age via the sea water Sr isotope curve. So the Sr-atoms have not changed much since then and it is fair to conclude, that most Ca-atoms also have not been exchanged.

 

You may try googling for this:

strontium isotope seawater curve dating

 

Franz Bernhard