Questions regarding the 'burn test'

[Jaybot]

As the title states, I have a few questions regarding the burn test.

We hunt glacial deposits in eastern Kansas, and find many bones, some obviously not fossil (we chuck these) and some that are definitely fossil.

I do understand that the river tends to darken bones, and give the appearance of fossil.  However, we have found several bones that have the right color to be fossil,

are exceptionally heavy for their size, and 'feel' right to be a fossil.  Strangely though, when I do the burn test on them, they will not char or burn but give off a more subtle 'burnt hair' smell.

Of course, on definite non-fossil bones, they smell badly and tend to usually char/burn. 

SO, my question:  Is the burn test a definite decider on whether a bone is fossil or not?  I have heard of Bison Latifrons bones not passing the burn test, yet they are without question 'fossils'.

Also, I know it doesn't really apply to this, but I have also heard of collagen being preserved even in dinosaur bones; at least in small amounts.  Could some collagen be preserved in some of our bones?

 

So, is the burn test definitive?

 

Or should I toss bones that char and burn, but ones that smell but do not burn, keep?

 

Hopefully y'all understand what I'm getting at here.

Thank you so much in advance

[Harry Pristis]

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

"Fossilized" (along with "petrified") is a near meaningless term in this specialized forum. 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 reinforced or replaced by minerals.

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." If the bone components (including the hydroxyapatite) are entirely replaced by exogenous minerals such as silica, it is said to be "replaced by -". If a bone is mineralized, it is more likely to be a fossil. If a bone is not mineralized, it is less likely to be a fossil. No absolutes, only likelihoods, because there are exceptions.

In the case of leaves and wood, as with bones, permineralization depends on the circulation of mineral-saturated groundwater. If there is limited or no circulation (or no suitable minerals in solution), then there is no permineralization. BUT, the organic remains - the leaves, or wood, or bone - are still fossils ("fossilized" if you like).

A 'burn test' or 'match test' will indicate only whether there is collagen remaining in a bone -- scorched collagen has an awful smell. Briefly apply an open flame (I prefer a butane lighter) to an inconspicuous area of the object . . . you cannot keep a pin hot enough long enough to scorch collagen. Tooth enamel contains hydroxyapatite, but doesn't contain collagen, so the 'burn test' on tooth enamel would be a waste of time.

The 'click test' - tapping a putative fossil against your teeth - was a joke that caught on. There are plenty of other things in the environment against which you can click a bone. Don't put the remains of dead, decomposed animals in your mouth.

[Jaybot]

I truly appreciate the informative response Harry, however I don’t think I explained myself well.  My point is:

 

Seeing as some fossils do retain collagen, the burn test is then not absolutely definitive.-?

 

I do believe that it is a valuable test, and is usually accurate.  I’m just saying that it may not be completely determine fossil vs bone in all instances. 
 

Thanks,

 

[Harry Pristis]

On 3/14/2024 at 10:12 AM, Jaybot said:

SO, my question:  Is the burn test a definite decider on whether a bone is fossil or not?  I have heard of Bison Latifrons bones not passing the burn test, yet they are without question 'fossils'.

Quote

Seeing as some fossils do retain collagen, the burn test is then not absolutely definitive.-?

I don't think your premise, "fossils do retain collagen," is well supported, no matter what you "heard."

 

There are no absolutes here.  If a fossil is a "float" specimen, geochronology is usually unreliable.  There are a number of laboratory tests that get close to absolute, but the burn/scorch test is testing accessible to all of us.  Combined with the much more arbitrary "10,000 years minimum," the convention holds the test as useful, as reliable a test as you can do at home. 

 

Bison remains are a particular problem because of confusion with cow remains.  Compounding the problem is the fact that bison were widespread on the western plains just 300 years ago.  Furthermore, earlier species of Bison are distinguishable only by the spread of their horns, according to a study done in Florida.  Bison post-cranials found as float or buried in creek banks are best labeled "Bison sp." 

[Jaybot]

I appreciate the response.  I believe I was attempting the burn test incorrectly.  Have a great day everyone!