A Bone And Shark Teeth

[Shellseeker]

This particular bone struck my eye. I have seen the tracks of bone borers (Osedax?) frequently in Dudong ribs, and less frequently in Megs. But this is oval or circular. So what do you think caused the pattern?

Then a picture of 2 megs around 1.5". Is this damage, wear, or what on the left tooth at the juncture of crown and root? Did the root grow into the center of the crown? Almost seems original, but others may differ.

[RickNC]

The two teeth together in the pic are just worn. The one on the left is missing some enamel.

[King of Snarge]

I have found several megs with borer damage to the root while diving the boneyard off of Venice Beach. Was the tooth found on the coast?

King of Snarge

[Shellseeker]

I have found several megs with borer damage to the root while diving the boneyard off of Venice Beach. Was the tooth found on the coast?

I am really curious. I went back and looked at the few larger megs I have found in the Peace at Wauchula (it is about 50 miles from the gulf but obviously covered with sea water at some point). The example Meg above is the only one I have of a Meg root with a bore hole.

There are a lot of dugong bones (mostly ribs) that have these bore holes. So I thought maybe the worms attack bone and tooth root material. On a recent trip, I found the fossil below: hard to identify , but it seems like Eagle Ray plate. with the horizontal layers.

Hopefully , others with knowledge of these worm borers will join this thread and thus add insight.

[tracer]

well, i'm not very knowledgeable concerning all the things that can bore holes in other things in marine environments, but i know there are multiple such critters. the polychaete osedax worms that bore into whalebones, boring sponges, a type of rock-boring urchin, rock-boring bivalves (like piddocks - can't remember what they're called), and don't know what else. so the problem for me would be if i found stuff like that trying to figure out whether it happened before or after the bone or tooth material became "rock", because seems like it could be either one. then on top of all that there are boring gastropods that bore into bivalves and such as a means of predation. lots of things seem to make holes in other things in a marine environment.

[Shellseeker]

Great Points, Tracer

I am thinking about the same questions you pose, and whether "community knowledge" can help to answer. So, King of Snarge finds some Megs that have bore holes in the root. I have one above that shows bore hole in the root. We have a lot of Meg collectors here. Of those Megs which have bore holes, how many are in the crown? Is this a difference after fossilization between the root and crown? If not, might indicate bore holes predate fossilization.

Maybe someone has a photo of an Osedax bored whalebone that can be compared to dudong rib bore holes.

In looking at the round circular holes in the possible ray plate, these are very similar to what I have seen in dudong ribs. This is about as "swiss cheese" looking as these get. Most of the dudong examples I have seen have 5-10 small bore holes in a 4-5" inch rib.

Now I be checking for bones that have holes.. I have odd interests

[Auspex]

Thinking about it, it seems that the Meg teeth I've seen with holes bored in the crown were badly worn; none of the holes went through enamel (it had been lost). This suggests (at least in these cases) that the holes were bored post-enamel loss; ie post fossilization.

[Boesse]

As far as the circular holes go - those are pholad borings, which are bored into any hard substrate. They can form in non-prefossilized bones and teeth, but these look prefossilized.

Traces of Osedax have thus far only adequately been reported from Eo-Oligocene whale bones from Washington, and only recently described for modern bones. Osedax traces are very small (1-3mm) circular boreholes that open up into a large eroded cavity below the bone surface, and differs from these very obviously flask-shaped pholad borings.

Bobby

[Paleoc]

http://www.thefossilforum.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=82888

Alligator or croc scute

Edited January 9, 2011 by Paleoc

[Paleoc]

Large (4 inch slant x 3.5 inch wide) bone valley meg with root borings. The one hole goes completely through.

Edited January 11, 2011 by Paleoc

[non-remanié]

i dont see much to suggest that this ever was fossil bone to begin with, so can we really attribute it to borers so quickly? would those pholad borings occur in say a forming phosphate nodule? i often see holey pieces exactly like this in phosphatic layers and the pieces usually have no discernable organic origin.

As far as the circular holes go - those are pholad borings, which are bored into any hard substrate. They can form in non-prefossilized bones and teeth, but these look prefossilized.

Traces of Osedax have thus far only adequately been reported from Eo-Oligocene whale bones from Washington, and only recently described for modern bones. Osedax traces are very small (1-3mm) circular boreholes that open up into a large eroded cavity below the bone surface, and differs from these very obviously flask-shaped pholad borings.

Bobby

Edited January 11, 2011 by toothpuller

[Boesse]

i dont see much to suggest that this ever was fossil bone to begin with, so can we really attribute it to borers so quickly? would those pholad borings occur in say a forming phosphate nodule? i often see holey pieces exactly like this in phosphatic layers and the pieces usually have no discernable organic origin.

Well, seeing as the bone appears to be phosphatized, I'd say there's a reasonably high probability that the bone has been fossilized. That element does not appear to be a crocodilian scute - all the holes are exactly the same size, perfectly circular, with the same internal shape to them. Some also appear to cross-cut each other.

Pholad borings can by default never occur in a forming phosphate nodule, because phosphate nodules grow and form only while buried. Pholad borings occur often in phosphate nodules (and terrigenous clasts) which have been reworked.

Bobby

[non-remanié]

Bobby,

I see nothing *that* convincing in the pictures to lead me to believe that Shelleesker's was once bone,(I agree definitely not a scute), but I understand that it could be bone heavily phosphatized into unrecognizability. Are you are saying that it is safe to assume that phosphatic debris like Shellseeker's as well as this one (courtesy www.fossilguy.com) originate as fossil bone or other organic phosphate debris (such as coprolites)? Or do you just give Shellseeker's a high probability because it does resemble bone a little more than fossilguy's nodule?

.steve

Well, seeing as the bone appears to be phosphatized, I'd say there's a reasonably high probability that the bone has been fossilized. That element does not appear to be a crocodilian scute - all the holes are exactly the same size, perfectly circular, with the same internal shape to them. Some also appear to cross-cut each other.

Pholad borings can by default never occur in a forming phosphate nodule, because phosphate nodules grow and form only while buried. Pholad borings occur often in phosphate nodules (and terrigenous clasts) which have been reworked.

Bobby

Edited January 11, 2011 by toothpuller

[Boesse]

Uhhhhh.... where to start.

1). I assumed from the start that it was correctly identified by shellseeker, and was primarily concerned with the traces. After you challenged the notion that it was bone, I looked closer; if you look at the first image (showing a cross section) you can clearly see pores that look like bone. I have no problem identifying that as bone.

2). Phosphatization cannot (or rather, does not) alter the physical morphology of the bone. It may obscure it, if the matrix is very dark and the same darkness and color as the bone.

3) Although bones are often phosphatized in the shallow marine fossil record (particularly along passive continental margins) - they comprise a very small minority of phosphatic material - in my master's thesis area, within bonebeds, there are roughly 1:50 or 1:100 bones per number of phosphatic nodules.

That second specimen looks like a phosphatic nodule.

Bobby

[non-remanié]

Thanks Bobby! That answers all my questions nicely. I did also see the pore-like bone structures in image1 but it didnt seem like quite enough for me to call it bone without a doubt (although a slightly better picture of that angle might). I also was hesitant because I saw absolutely nothing that made me think "eagle ray" as Shellseeker had postulated. I have no problem with it being bone, but I thought that you came to the conclusion it was bone based more on the fact of the borings being present than anything else. You had me confused for a while, but that 100:1 ratio sounds good to me, I did not think that fossilguy's could be anything but a nodular phosphate growth either.

Uhhhhh.... where to start.

1). I assumed from the start that it was correctly identified by shellseeker, and was primarily concerned with the traces. After you challenged the notion that it was bone, I looked closer; if you look at the first image (showing a cross section) you can clearly see pores that look like bone. I have no problem identifying that as bone.

2). Phosphatization cannot (or rather, does not) alter the physical morphology of the bone. It may obscure it, if the matrix is very dark and the same darkness and color as the bone.

3) Although bones are often phosphatized in the shallow marine fossil record (particularly along passive continental margins) - they comprise a very small minority of phosphatic material - in my master's thesis area, within bonebeds, there are roughly 1:50 or 1:100 bones per number of phosphatic nodules.

That second specimen looks like a phosphatic nodule.

Bobby

[Boesse]

I thought I'd mention - phosphate nodules are bored more often than bone and teeth. I'm not sure if that's due to the higher abundance of nodules, or if there is a higher frequency of boring among nodules than there is in bone.

Bobby