Looking for a definition of "lightning streak" in shark teeth.

[ynot]

Hey Hi Folks,

Had a discussion with @MeargleSchmeargl about the definition of the term "lightning streak (strike, mark)", as referred to sharks teeth.

I would like to get the opinion of the members on this one, just for clarification.

@Shellseeker, @sharktoothhunter, @MarcoSr, @siteseer, @Northern Sharks, @Sacha, @caldigger, @digit, @isurus90064, @NSRhunter, @sixgill pete, @squali, @njfossilhunter, @Al Dente, @frankh8147, @jcbshark, @John Hamilton, @fossilselachian, @Auspex, @Fossildude19, @Boesse, @Paleoc, @Troodon  @obsessed1,  (if I missed anyone please feel free to tag them. if I missed You please feel free to reply.)

 

 

 

The question is --  What are lightning strikes (streaks, marks) as applied to shark teeth?

 

Thanks Y'all!

 

Tony

 

[Doctor Mud]

I think this term is most often used to refer to the spider web pattern left by contact of fossil tooth enamel with in-situ plant roots. The weak acids secreted by the roots (or by their decay) etches a spider web or lightning pattern into the tooth enamel.

Ive seen this a few times in reference to Bone Valley megs.

 

Here is an example from the forum of a mako:

 

 

 

 

 

[digit]

Yup. That's how I understand this marking pattern as well.

 

Cheers.

 

-Ken

[izak_]

I agree with that. 

[NSRhunter]

Right on Doctor Mud!

[Al Dente]

I agree with plant roots causing the pattern.

[Shellseeker]

Agree with the experts.  The thing I find most curious is this phenomenon seems to have higher probability of modifying shark teeth than mammal teeth, at least in my hunting grounds.

There is likely a reason that escapes me at this moment.

[jcbshark]

I'm not sure what causes it but I have pulled teeth right from the layer they were deposited in that have shown these marks and they were 15-20 feet beneath the current ground level. Maybe it was done when the fossil was still relatively " new" and closer to the surface? I do notice around me some areas seem more likley to produce teeth like that. 

[sixgill pete]

I agree with Doctor Mud also on this. It is always a pleasure to find one of these beauties. 

[RJB]

Thanks to @Doctor Mud, it now makes perfect sence now.

 

RB

[ynot]

Thanks for the replies Guys!

For those that have not made a comment--- Please feel free to add new comments here, I am looking for more comments one way or the other.

 

2 hours ago, jcbshark said:

I'm not sure what causes it but I have pulled teeth right from the layer they were deposited in that have shown these marks and they were 15-20 feet beneath the current ground level. Maybe it was done when the fossil was still relatively " new" and closer to the surface? I do notice around me some areas seem more likley to produce teeth like that. 

Some plants are known to have roots that go 160 feet below the surface. So 20 feet would be well within the range of roots.

[Brett Breakin' Rocks]

  I'd also like to say my understanding has always been the streaks of 'lightning' seen on the surface/subsurface of teeth enamel.  It is often described online for collectors as lightning strikes or marbling so it's really just a descriptive term. Though I think the root theory is suspect in some cases.  As stated @jcbshark these teeth sometimes come from layers that may never have seen a root of any sort. 

 

  I'd be curious if it wasn't a similar process that creates dendrites ... or some sort of mineral leeching across the surface or under the surface slowly over time.  Maybe minute cracks in the rock/clay acting like a stencil on the surface.  ... and/or small imperfections acting as pathways through the enamel for the leeching minerals. 

 

PS. This Hemipristis that popped up on our favorite auction site was just gorgeous.

 

 

Photo Source Credit : CalUsa31 ( Zach Frignoca ) Primitive Past

 

 

 

Cheers,

Brett

[Auspex]

I would love to bury some Isurus in a flower pot to quantify this....

Do teeth from locations that preserve (or even enrich?) the phosphate level in the tooth attract more plant root erosion? How long does it take to visibly etch the enamel? Are different species' teeth more susceptible than others (Hemipristis seems particularly prone, anecdotally). Which plants are the most aggressive at etching them?

Such are my musings....

[FossilDudeCO]

I came across this post by accident, but I may have something to add.

 

@Troodon May be able to help as well.

 

I have seen this pattern on lots of Dino teeth for sale as well and have heard exactly @Doctor Mud hypothesis.

You see them as well, but not as commonly on fossils from the White River Formation that @jpc could potentially verify.

 

I think plant sounds logical for the shark teeth, since it also happens with a lot of other teeth.

[Doctor Mud]

I think one of @ynot's major aims was to see if there was a consensus as to whether the informal term "lightning strikes" refers to cracks in the enamel or some sort of chemical alteration of the tooth enamel (e.g. Etching by acids).

It is looking like a consensus is forming that "lightning strikes" are formed by a chemical alteration of the tooth enamel.

It could be that more than one process can lead to such chemical alteration, which I think is possible, either contact with plant roots or leaching by groundwater, perhaps through small cracks in the matrix? This might be the case for teeth that might not have been in contact with plant roots.

[siteseer]

On August 5, 2017 at 8:10 AM, ynot said:

Thanks for the replies Guys!

For those that have not made a comment--- Please feel free to add new comments here, I am looking for more comments one way or the other.

 

Some plants are known to have roots that go 160 feet below the surface. So 20 feet would be well within the range of roots.

 

 

Hi Tony,

 

I'm a little skeptical of the plant root idea too as a complete explanation.  That would mean that you can't get that kind of discoloration pattern at a site that had always been marine or one that had been marine and became desert without much of a vegetated environment in between.  I think it's also like how fossils get their color - water seeping through rock bringing a wash of solutions with it to add colors but sometimes washing the color away in odd patterns.  

 

Acids don't come just from plant roots.  It depends on the minerals in the rock and even rainwater can vary in acidity.

 

The funny thing is that a discolored tooth is often less desirable to a collector than one with nice color, but if the discoloring takes on some recognizable pattern or some odd shading or splotching, suddenly it's an art piece. 

 

Jess 

[caldigger]

I seem to have problems with the plant root theory myself. How is it that teeth (referring to shark in my argument) with the " lightning" pattern are often found in between layers of teeth that do not sport this coloring?  I would think if roots were the culprit, then the teeth found above them and around them would have this as well. It just doesn't make sense to me that in a group of say twelve teeth found in a one square foot area, that you may only find one with the markings. 

[Doctor Mud]

3 hours ago, caldigger said:

I seem to have problems with the plant root theory myself. How is it that teeth (referring to shark in my argument) with the " lightning" pattern are often found in between layers of teeth that do not sport this coloring?  I would think if roots were the culprit, then the teeth found above them and around them would have this as well. It just doesn't make sense to me that in a group of say twelve teeth found in a one square foot area, that you may only find one with the markings. 

 

The conclusion that I have come to from this discussion and some thought is that plant roots represent one possible mechanism that may create an environment conducive to the etching of the enamel on shark teeth. There are many different processes that could achieve this and plants roots represent only one subset of a number of processes. All that is needed is some way to alter the pH and possibly interact with the tooth in different ways at the tooth scale. Plant roots or differential interaction by groundwater would suffice.

 

I would offer a couple of possibilities for individual layers only having lightning strikes or not all teeth in an individual horizon having them. Plant roots may only contact with some teeth in a individual layer. Also if there is an unconformity with sub-aerial exposure plant roots may contact one layer, then re-deposition of marine sediments. Re-working of teeth that were in root contact and mixing into an assemblage may be possible.

These are possibilities, but not really required if we consider that other mechanisms can lead to the lightning strike pattern.

This multiple mechanism hypothesis would be the simplest solution.

[Doctor Mud]

I thought this paper was interesting:

 

http://iopscience.iop.org/article/10.1088/1742-6596/499/1/012015/pdf

 

Influence of depositional environment in fossil teeth: a micro-XRF and XAFS study 

 

It talks about fine scale variations in diagenesis of tooth enamel resulting from dissolution and recrystallisation of bioapatite.

We have a micro-XRF at work. Never thought of scanning fossil teeth before......

[jpc]

I am not going to say much about shark teeth, but with dinosaur bones it is very common to see color changes due to plant roots. The roots line the surface of the bone and take some of the minerals, leaving bleached areas where they were.  And you can see this first hand  by peeling away nets of roots, and there is the same pattern you just removed, but on the bone itself.