How to tell if a bone is a fossil?

[PaleoWilliam]

The title states my question.

[Jesuslover340]

1. Density. A fossilized bone will be much more dense than if it were modern.

2. Hot needle test. If you put the hot tip of a needle to modern bone, it produces a stench. Fossilized bone doesn't.

3. Not always, but coloration can sometimes help indicate if a bone is a fossil or modern. If the fossil in question is as white as a modern bone, use the above two methods to help you deduce.

[frankh8147]

It can depend on the preservation and in places where the hot needle doesn't work (I.E. my neck of the woods and at least one or two locations in Europe) it can be almost impossible on a case-to-case basis. If a find can be significant, it's worth it to take it to an expert; they may be able to spot something diagnostic on the bone to tell what creature it is from; some can also be identified by bone structure, but even then, it can be tough to assign it to a known species (that's where the term 'chunkosaurus' comes from).

[Harry Pristis]

This is the second reference to a "hot needle test" that I've read today. How could you keep a needle hot enough, long enough to scorch residual collagen?! The test is a "flame test" or a "match test" or a "burn test" using an open flame on a least-interesting part of the bone.

There seems to be endless misunderstanding about the term "fossilized."

"Fossilized" is a near meaningless term. The term is often substituted for "mineralized" in describing a bone or tooth. But, fossilized doesn't always equate to mineralized because many fossils are not impregnated or replaced by minerals. European cave bear fossils are a well known example of non-mineralized bones.

Bone is primarily composed of hydroxyapatite and collagen. Hydroxyapatite is an inorganic compound of calcium, phosphate, and hydroxide which is organized in a crystal latticework that gives bone (and teeth) structural rigidity. It preserves well as a fossil under some conditions.

Collagen is a fiberous protein that serves as connective tissue in bones and muscles. It does not preserve well in a fossil. As collagen decomposes, it may be replaced in the hydroxyapatite latticework by minerals from the depositional environment (e.g. silica dioxide dissolved in

groundwater).

Bone reinforced with exogenous minerals is said to be "mineralized."

[jpevahouse]

Thinking of something as a fossil was simple, during the simpler time of my innocent youth. Age brings experience, complexity and a end to the innocence of youth. The problem of calling a bone a fossil really only pertains to those within the more recent past, late Pleistocene. I have no problem calling a bone from the Oligocene era a fossil. I think for communication sake it works, most people would immediately know it's composed of rock, no bone left. But if I found a bone from the late Pleistocene era there's a good chance it still contains much of it's original composition and probably some degree of mineralization. Then it's debatable but I doubt most people really care.

I could write my posts in classical Chinese but I don't do so because few if any on the Fossil Forum would understand. I don't over use scientific terminology and complex scientific explanations on the forum either because I'd be talking over plenty of people's heads or talking down to them. I would prefer to communication in language most understand. So if fossil works for most folks then fossil is a legitimate term here.

I remind some folks, this is called "The Fossil Forum", not the "Mineralized Forum" or the "scientific blah, blah, blah forum." Most of us I'm sure aren't scientists.

[JohnJ]

The Fossil Forum is not only a place to share experiences at a young, or beginner, level, it is also a place to increase the accuracy of your knowledge of fossils. We are certainly not all scientists, but most of us come here to learn more...hence, the title of this topic.

I appreciate the high level of knowledge expressed on TFF, and the choice each of us has to pursue it further, or not.

[Harry Pristis]

Thinking of something as a fossil was simple, during the simpler time of my innocent youth. Age brings experience, complexity and a end to the innocence of youth. The problem of calling a bone a fossil really only pertains to those within the more recent past, late Pleistocene. I have no problem calling a bone from the Oligocene era a fossil. I think for communication sake it works, most people would immediately know it's composed of rock, no bone left. But if I found a bone from the late Pleistocene era there's a good chance it still contains much of it's original composition and probably some degree of mineralization. Then it's debatable but I doubt most people really care.

I could write my posts in classical Chinese but I don't do so because few if any on the Fossil Forum would understand. I don't over use scientific terminology and complex scientific explanations on the forum either because I'd be talking over plenty of people's heads or talking down to them. I would prefer to communication in language most understand. So if fossil works for most folks then fossil is a legitimate term here.

I remind some folks, this is called "The Fossil Forum", not the "Mineralized Forum" or the "scientific blah, blah, blah forum." Most of us I'm sure aren't scientists.

We should understand the distinction between "fossil," a useful noun and adjective, and "fossilized," a verb (an action word) past participle.

"Fossilized" implies a change in status of the organic remains, but all that has to happen to become fossilized is the passage of time beyond the (very arbitrary) 10,000 years. At best, "fossilized" tells us that the remains "have grown old."

What I have asserted is that "fossilized" doesn't tell us much. That the term is usually substituted for "mineralized." The term "mineralized" is preferable because it carries more meaning: It suggests other possible descriptors, "non-mineralized" or "partly-mineralized". These latter terms may tell us something about the condition of the specimen and/or its taphonomy. Useful.

I am always amazed to see an attack on learning more, becoming more sophisticated in talking about fossils. How ironic that someone actually thought that attack was "Informative".

Edited March 16, 2016 by Harry Pristis

[Ash]

Are impressions mineralised? Nothing's replaced them. But they are fossils. I say "fossilised" is a valid thing to say. Wasn't even the question in the topic.


Also a needle isn't hard to keep hot enough.

[JohnJ]

Are impressions mineralised? Nothing's replaced them. But they are fossils. I say "fossilised" is a valid thing to say. Wasn't even the question in the topic.

Also a needle isn't hard to keep hot enough.

Since the topic is a question about "bone", other types of fossils are not addressed.

You're right about the needle. However, it typically would not have the surface area needed to generate enough heat to scorch residual collagen.

[Ash]

Get a bigger needle

*wonders how big something can be and still be classified as a "needle".*

Anyways, back on topic!

William - guessing you're looking in Pleistocene deposits around Texas? Something someone showed me is you scrape it with your teeth. I guess a fingernail would work? But a fossil (at least the Pleistocene around here) doesn't chalk to that.

I still have trouble sometimes determining if bone is fossil or not, and I've been searching this one place going on 11 years now. Weight seeks to mean nothing - found megalania that weighs as much as a normal dried out bone, then some are very heavy for the same size piece.

Colour also - fossils within meters of eachother range from orange, blue, white, black, brown. There's not a whole lot of consistency. Although some places it tends to be more of one colour than another. We also don't have tannins staining the water to colour regular bone etc.

Edited March 16, 2016 by Ash

[Jesuslover340]

Knitting needle!

I've personally used the hot needle test and it's worked easily for me, but I've also been told that I have heightened senses concerning smelling, touch, taste, and hearing. Probably to compensate for my eyesight. I never really considered it until now that I would be able to smell something others might not be able to. So concerning such a test, I would just say it depends on the person. And the burning stench is a result of how much collagen is left. May be fully fossilized, petrified, or modern. Such a test really only helps with a fossil that has no more collagen in it. Hope this helps.

[Auspex]

"Fossilized" is a useful, if inexact term. I cite its use in a recent Science Digest article:

Thousands of Tully Monsters eventually were found at the site, embedded in concretions -- masses of hard rock that formed around the Tully Monsters as they fossilized.

It imparts just enough information for the purpose. Sometimes, when you're asked what time it is, the inquirer has no need to know how to build a clock.

[Ridgehiker]

It's a great question. Simetimes I am not sure when roaming our Cretaceous badlands.

I've collected hundreds of raptor phalanges but every so often find a specimen that stymies me. Dino raptor or...a couple hundred year old bird of prey digit? Weasel family? I'll stick it on my tongue...tap it on my front teeth. Look at the distal and proximal ends, etc. Try scratching it. I'll toss it into the zip lock bag with the rest of the day's loot and can only tell once I look at it under the microscope.

re the word fossil. Lots of definitions. Important in science is to be consistent with whatever definition you use. I use a very broad term. 'Evidence of the past'. This can include evidence of biological origin ( shells, bones, etc.) or non biological such as sea floor ripples.

[Auspex]

...I use a very broad term. 'Evidence of the past'. This can include evidence of biological origin ( shells, bones, etc.) or non biological such as sea floor ripples.

I like this. The concept is simple and inclusive.