Since We Are Talking Aurora...

[Frank Menser]

I can't be positive without looking at it in person, but what you are calling a sloth tooth looks like a section of walrus tusk. The inner core of a walrus tusk looks grainy and the outer surface looks like ivory, compact and smooth. The creek does produce walrus material, especially tusk sections. I have seen one complete tusk from there that is around a foot long. The guy who found it thought it was a rib bone and threw it down. Another collector thought it was a saber cat tooth and picked it up. It turned out to be a very nice walrus tusk. The curve to the specimen also fits in well with walrus but every sloth tooth I have seen was straight. I have not found a complete or even near complete tusk from there but I have found sections.

Got to say there is room for arguement there as the ID was made by a friend and I have not been able to confirm it. Definitely not a rib though...

[PaleoRon]

Check out the third pic on this post and see if the cross section looks the same. I agree that it is not a rib, the structure is wrong.

http://www.thefossilforum.com/index.php?sh...ic=5243&hl=

[Frank Menser]

Got to laugh here. that post is from my collecting buddy. I was there when he found it.

One problem though. I forgot to mention that the "tooth" I posted is very flat-not round like a walrus tusk. It appears to be half of the orrigional split lengthwise. The dimensions;

3.5" x 1.25" x .50"

[PaleoRon]

The tusk frags that I found are not from a round tusk. They are flattened side to side and have an almost rectangular cross section. The fossil walrus tusks are different than the modern tusks.

[Metopocetus]

The reason I say it is a barnacle cast is that I have found several mastadon tooth fragments, from less than an inch to half a tooth, in the same creek where your material was found and several dozen of the barnacle casts, some almost identical to the one you have. Keep in mind that some of the people working the Smithsonian table at the fair are not museum employees but volunteers. The best guy to talk to there is Fred Grady. He is a generalist and has a broader range of knowledge than the other people who show up to work the festival. Most of the guys at the table are cetacean specialists and you will often see them asking Fred for identification. The other thing to consider is that no one there is an invertebrate specialist. I know this because I personally know the individuals on the Smithsonian fossil festival crew.

Fred knows everything - very smart guy.

[Harry Pristis]

Harry,

I'm fairly busy this evening, but tomorrow I have time to track down those references. Just to be 100% certain we are on the same page, we are both talking about diagenetic alteration of primary biogenic phosphate minerals in bone, right?

Bobby

What I objected to was the faulty logic of your statement:

Phosphate will begin to replace the bone itself, and once most of this has occurred, will begin to precipitate in the pore space within the bone.

How can anything "precipitate in the pore space within the bone" when the bone is gone, replaced by phosphate??

What I suggested was that "phosphatic bone" is not something that occurs in Florida phosphates (and not in NC phosphates, AFAIK). A chemical process involving upwelling currents off California is mildly interesting, but try to connect that process to what we actually experience with fossils here on the East Coast.

The black color of some East Coast fossils and of some California fossils is not a good connection because, as has been pointed out, black is not the typical color of phosphate fossils on the East Coast.

[Harry Pristis]

The tusk frags that I found are not from a round tusk. They are flattened side to side and have an almost rectangular cross section. The fossil walrus tusks are different than the modern tusks.

I agree with 'PaleoRon'. Walrus tusks, fossil or modern, are markedly flattened side-to-side. This fragment could easily be a section of walrus tusk.

[Guest bmorefossil]

well since harry wont answer my question i might as well bring up this question, can you help me out with reworked fossils, why does it seem many of them are black? I thought this may have something to do with the whole phosphatic bone in one way or another.

[Boesse]

Like I said, I wasn't giving an East Coast example. But upwelling is generally how phosphate deposits and phosphogenesis come about. In any event, I was deriving information from a thesis (Karen Friede, 1987) done at UC Santa Cruz.

"How can anything "precipitate in the pore space within the bone" when the bone is gone, replaced by phosphate??"

Ah, I'm going to go ahead and call this nit-picky. For one, the bone is already phosphate, just altered to a different more diagenetically stable phosphate mineral phase. Saying "then phosphate is precipitated within the porespace of the bone" is a lot easier (and I suspect most folks wouldn't have any problem with this, as thus far they have not appeared to, save one) than saying "then phosphate is precipitated within the pore space of the former bone, now altered to more diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of said bone". I think, considering that I was not exactly writing a scientific article, and keeping it to terminology vernacular enough to be useful for forum members (I am, after all, using a forum, on the internet, of all places), that such shorthand is admissable.

Additionally, by your logic, if that no longer constitutes a bone, than that logically leads to calling all "bones" with diagenetically altered phosphate chemistry not bones at all, but "diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of the original bone", which, as it appears to me at least, is longer and mildly redundant.

Bobby

[Frank Menser]

If it will help, here are some edge on pics. Note that there is more than half the "tooth" there. It is more blade-like in proportion.

This is what I have ben using to compare it. On display at the museum.

How about this?

I think what I am going to do is take the items in question to Aurora at the next Fest. Hopefully some of you might be there. Which is a sneaky way of getting to meet y'all. I noticed the lack of invertebrate specialists at Aurora. I stumped them with some echinoids I had from S. Florida and from France. Had to go to Lou Zachos (University of Texas) for an ID on them.

looks like this piece has taken on a life of its own. I am going to start a new thread so all the pics can be together.

[Carl O'Cles]

I would bet the house that the first item posted is a phosphate nodule. I take nothing from the pattern since there is symmetry everywhere in nature even amongst non living things. Just my two cents

[tracer]

Like I said, I wasn't giving an East Coast example. But upwelling is generally how phosphate deposits and phosphogenesis come about. In any event, I was deriving information from a thesis (Karen Friede, 1987) done at UC Santa Cruz.

"How can anything "precipitate in the pore space within the bone" when the bone is gone, replaced by phosphate??"

Ah, I'm going to go ahead and call this nit-picky. For one, the bone is already phosphate, just altered to a different more diagenetically stable phosphate mineral phase. Saying "then phosphate is precipitated within the porespace of the bone" is a lot easier (and I suspect most folks wouldn't have any problem with this, as thus far they have not appeared to, save one) than saying "then phosphate is precipitated within the pore space of the former bone, now altered to more diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of said bone". I think, considering that I was not exactly writing a scientific article, and keeping it to terminology vernacular enough to be useful for forum members (I am, after all, using a forum, on the internet, of all places), that such shorthand is admissable.

Additionally, by your logic, if that no longer constitutes a bone, than that logically leads to calling all "bones" with diagenetically altered phosphate chemistry not bones at all, but "diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of the original bone", which, as it appears to me at least, is longer and mildly redundant.

Bobby

of course the other qualifier that everybody oughta be using on here is by stating the geological age of things as a point in time rather that a permanent label. like, "this is a pseudomorph of fluorapatite after hydroxylapatite in the shape of a femur, from the early late miocene, at the moment. 'cuz in a few million years, it'll be too old to be called miocene unless somebody shifts the scale of years for the miocene. and of course they'll need to change the names of the pleistocene and holocene cause they'll be misleading. but really, all this conversation should have been saved for "literal thursday".

[tracer]

well since harry wont answer my question i might as well bring up this question, can you help me out with reworked fossils, why does it seem many of them are black? I thought this may have something to do with the whole phosphatic bone in one way or another.

bmore - i posted my pet theory on that earlier from some reading i did yesterday. i don't think the fact that they are "reworked" necessarily plays into it, but i believe certain bacterial action in the presence of organic material in a reducing environment with a rising pH due to the phosphate works on iron compounds to create iron sulphide, which is black. if i'm wrong about the precise nature of it, i still think it's a chemical reaction that occurs under certain conditions in which phosphate is present. if you got back some time and search all my posts (yeah, right), i asked a similar question about the two different types of baculites fossils i've found at the north sulphur river. they're found in red matrix, and some have the white aragonite shells preserved and are filled with red matrix, and some are black phosphatic molds.

[non-remanié]

Harry, I am sorry, I guess the authors of Lee Creek vol III are as illogical as I am. You can refer to page 245,289, 300 of the pdf (296,285, 241 of text) just for starters. I don't see any reason why the Bone Valley and Peace River fm. phosphates of florida, which were formed during the same episodes of phosphogenesis as the Yorktown and Pungo River fms of NC, would be somehow immune from this phenomenon.

http://www.sil.si.edu/smithsoniancontribut...o/SCtP-0090.pdf

&

Phosphate Deposits of the World: Genesis of Neogene to Recent Phosphorites

By William C. Burnett, P. J. Cook, Stanley R. Riggs, J. H. Shergold, International Geological Correlation Programme Project 156 Phosphorites, Arthur John George Notholt

Edition: illustrated

Published by Cambridge University Press, 1990

ISBN 0521333709, 9780521333702

480 pages

[Harry Pristis]

Harry, I am sorry, I guess the authors of Lee Creek vol III are as illogical as I am. You can refer to page 245,289, 300 of the pdf (296,285, 241 of text) just for starters. I don't see any reason why the Bone Valley and Peace River fm. phosphates of florida, which were formed during the same episodes of phosphogenesis as the Yorktown and Pungo River fms of NC, would be somehow immune from this phenomenon.

http://www.sil.si.edu/smithsoniancontribut...o/SCtP-0090.pdf

&

Phosphate Deposits of the World: Genesis of Neogene to Recent Phosphorites

By William C. Burnett, P. J. Cook, Stanley R. Riggs, J. H. Shergold, International Geological Correlation Programme Project 156 Phosphorites, Arthur John George Notholt

Edition: illustrated

Published by Cambridge University Press, 1990

ISBN 0521333709, 9780521333702

480 pages

Huh? What phenomenon are you talking about? It would take 15 minutes to download that huge PDF file -- why don't you just give us all the highlights.

[non-remanié]

Normally I wouldn't bother but since you are extra special... it basically lists some blackened Lee Creek bone specimens derived from phosphatic zones as being "phosphatized". Basically exactly what I claimed when I referred to meg teeth from the same intervals and of similar preservation. So, like I said, I guess I am as illogical as the authors of the paper. GOT IT NOW??? Next nitpick??? :>

Huh? What phenomenon are you talking about? It would take 15 minutes to download that huge PDF file -- why don't you just give us all the highlights.

[Harry Pristis]

Normally I wouldn't bother but since you are extra special... it basically lists some blackened Lee Creek bone specimens derived from phosphatic zones as being "phosphatized". Basically exactly what I claimed when I referred to meg teeth from the same intervals and of similar preservation. So, like I said, I guess I am as illogical as the authors of the paper. GOT IT NOW??? Next nitpick??? :>

That's great, 'toothpuller'! Were they mammal bones?

Now then, how will we know a phosphatized mammal bone from Lee Creek when we find one? I mean, how will a phosphatized bone be distinguished from a silicified bone? Is there something more than the black color and labratory analysis?

Gosh, we already know that color is not very reliable. I guess that leaves lab analysis, eh.

[Harry Pristis]

Like I said, I wasn't giving an East Coast example. But upwelling is generally how phosphate deposits and phosphogenesis come about. In any event, I was deriving information from a thesis (Karen Friede, 1987) done at UC Santa Cruz.

"How can anything "precipitate in the pore space within the bone" when the bone is gone, replaced by phosphate??"

Ah, I'm going to go ahead and call this nit-picky. For one, the bone is already phosphate, just altered to a different more diagenetically stable phosphate mineral phase. Saying "then phosphate is precipitated within the porespace of the bone" is a lot easier (and I suspect most folks wouldn't have any problem with this, as thus far they have not appeared to, save one) than saying "then phosphate is precipitated within the pore space of the former bone, now altered to more diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of said bone". I think, considering that I was not exactly writing a scientific article, and keeping it to terminology vernacular enough to be useful for forum members (I am, after all, using a forum, on the internet, of all places), that such shorthand is admissable.

Additionally, by your logic, if that no longer constitutes a bone, than that logically leads to calling all "bones" with diagenetically altered phosphate chemistry not bones at all, but "diagenetically stable phosphate minerals that reasonably approach or retain the primary morphology of the original bone", which, as it appears to me at least, is longer and mildly redundant.

Bobby

I know you don't mean to insult the members of the forum. I think that those who are reading this thread can follow your logic, at least. Writing clearly is not the same as writing in the jargon of biology. And the practice of clear, persuasive writing will help you in your professional career later.

Mammal bone composition is 2:1 calcium:phosphorus, so saying that mammal bone is already phosphate is an exaggeration. It might help if we just used "fossil mammal bone" or "FMB" when we are talking about the remains that are acted upon. We can reserve "bone chemicals" for the mammal bone material (2:1 Ca:Po).

Your original statement: Phosphate will begin to replace the bone itself, and once most of this has occurred, will begin to precipitate in the pore space within the bone.

Modified for clarity: Phosphate will begin to replace the bone chemicals [themselves], and once most of this has occurred, will begin to precipitate in the pore space within the FMB.

Even with this adjustment, your statement still tends to conflate a chemical process (a shift from one form of phosphate to another) with a mechanical process (filling the pore space within the FMB as opposed to chemically bonding with the altered phosphate).

I don't think we need worry about what we're going call "all" mammal bones with diagenetically altered phosphate chemistry. You haven't been able to show us one yet.

Sooo . . . How will I identify a mammal bone with diagenetically altered phosphate chemistry if I find one here in Florida? Is it the black color? We know that lots of black fossils are found without a significant association with phosphate. I guess it would take some lab testing, eh?

[Guest bmorefossil]

bmore - i posted my pet theory on that earlier from some reading i did yesterday. i don't think the fact that they are "reworked" necessarily plays into it, but i believe certain bacterial action in the presence of organic material in a reducing environment with a rising pH due to the phosphate works on iron compounds to create iron sulphide, which is black. if i'm wrong about the precise nature of it, i still think it's a chemical reaction that occurs under certain conditions in which phosphate is present. if you got back some time and search all my posts (yeah, right), i asked a similar question about the two different types of baculites fossils i've found at the north sulphur river. they're found in red matrix, and some have the white aragonite shells preserved and are filled with red matrix, and some are black phosphatic molds.

no no no i was talking about reworked material in general, yea ill be sure to go back some posts and read what you had to say.

[JohnJ]

Seriously, this thread is great on so many levels...like an exquisite fencing match.

[non-remanié]

Harry I think you should show us since you claim to know that all FMB in florida is "silicified" rather than "phosphatized". We are not talking about secondary permineralization from stream waters as far as I can tell. We all probably would agree that the ex situ bones and teeth you find in rivers in florida have been stained and permineralized further, but this is not what we are talking about.

I know you don't mean to insult the members of the forum. I think that those who are reading this thread can follow your logic, at least. Writing clearly is not the same as writing in the jargon of biology. And the practice of clear, persuasive writing will help you in your professional career later.

Mammal bone composition is 2:1 calcium:phosphorus, so saying that mammal bone is already phosphate is an exaggeration. It might help if we just used "fossil mammal bone" or "FMB" when we are talking about the remains that are acted upon. We can reserve "bone chemicals" for the mammal bone material (2:1 Ca:Po).

Your original statement: Phosphate will begin to replace the bone itself, and once most of this has occurred, will begin to precipitate in the pore space within the bone.

Modified for clarity: Phosphate will begin to replace the bone chemicals [themselves], and once most of this has occurred, will begin to precipitate in the pore space within the FMB.

Even with this adjustment, your statement still tends to conflate a chemical process (a shift from one form of phosphate to another) with a mechanical process (filling the pore space within the FMB as opposed to chemically bonding with the altered phosphate).

I don't think we need worry about what we're going call "all" mammal bones with diagenetically altered phosphate chemistry. You haven't been able to show us one yet.

Sooo . . . How will I identify a mammal bone with diagenetically altered phosphate chemistry if I find one here in Florida? Is it the black color? We know that lots of black fossils are found without a significant association with phosphate. I guess it would take some lab testing, eh?

[Boesse]

I don't think we need worry about what we're going call "all" mammal bones with diagenetically altered phosphate chemistry. You haven't been able to show us one yet.

Sooo . . . How will I identify a mammal bone with diagenetically altered phosphate chemistry if I find one here in Florida? Is it the black color? We know that lots of black fossils are found without a significant association with phosphate. I guess it would take some lab testing, eh?

Here are some papers and abstracts that you should read (these are not restricted to phosphate alteration through diagenesis):

Rao et al. 2008. Miocene phosphorites from the Murray Ridge, northwestern Arabian Sea. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 260, no. 3-4, pp.347-358

Martill, D. M. 1991. Bones as stones: The contribution of vertebrate remains to the lithologic record. pp. 270–292 in S. K. Donovan (ed.), The Processes of Fossilization. Columbia Universtity Press, New York.

Jacque et al. 2008. Implications of diagenesis for the isotopic analysis of upper Miocene large mammalian herbivore tooth enamel from Chad. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 266, no. 3-4, pp.200-210

Trueman et al. 2008. Why do crystallinity values fail to predict the extent of diagenetic alteration of bone mineral? Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 266, no. 3-4, pp.160-167

Pasteris and Ding, 2006. Fluoridation of a fossil horse tooth from the "pre-Colgate era". Abstracts with Programs - Geological Society of America, vol.38, no.7, pp.46, Oct 2006

Harwood et al. 2005. A comparative study of authigenic mineralization and rare earth element geochemistry of vertebrate microfossil assemblages in the Campanian Judith River Formation of Montana. Geological Society of America, 2005 annual meeting, Salt Lake City, UT, United States, Oct. 16-19, 2005

Goodwin et al. 2007 Elemental composition and diagenetic alteration of dinosaur bone; distinguishing micron-scale spatial and compositional heterogeneity using PIXE. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 253, no. 3-4, pp.458-476, 27 Sep 2007

Viana et al. 1998. Preservation of biomineralized tissues of fishes from the Santana Formation (Lower Cretaceous of the Araripe Basin, NE-Brazil). Estudos Tecnologicos, vol.21, no.46-47, pp.91-100

There were hundreds of other hits on georefs for this sort of stuff - it's taphonomy 101. Fossilized bone changes chemically, often involving phosphate minerals. I could have posted dozens of other articles as well, but I have actual things to do today, and dinner to eat.

Here are just a few from a cursory search of the literature. As far as lab tests, sure - that is the only real way to tell if something is phosphatized. OR SILICIFIED. Like toothpuller asks, how do you know your bones are silicified? Have you done the "lab test"?

In the case of rock units I was talking about, those were subjected to "lab tests" as you call them (see my above posts - petrographic/petrologic, SEM analysis, X-Ray diffraction). As were the bones in the studies I just mentioned - these had different chemical/mineral alterations not just due to phosphate recrystallization, but also to other chemical and mineral phases.

Also, give us an example of bones in-situ (associated with phosphorite deposits, per what I was talking about) that are blackened by a process other than phosphatization.

I don't understand how precipitation of phosphate minerals within the pore space of a bone is mechanical. That's still a chemical process, pure and simple. Unless of course you can explain how this can be 'mechanical' and not chemical. (FYI Merriam webster defines mechanical as: caused by, resulting from, or relating to a process that involves a purely physical as opposed to a chemical or biological change or process; And in fact I should mention that precipitation of any solid from a liquid, including the precipitation of phosphate within bone pores, is "Chemical Precipitation").

Lastly, most naturally occurring phosphate minerals contain more calcium than phosphate anyway, so that argument is pretty much a straw man.

Bobby

[tracer]

Seriously, this thread is great on so many levels...like an exquisite fencing match.

yeah, but i made it to the semifinals in a fencing tournament years ago and primarily saw fairly equally matched lunging, parrying and riposting - as i recall nobody was throwing beachballs as distractors or claiming that the foils were epees.

[Frank Menser]

Personally, I prefer Sabre....

(Ok..I just edited this and everything I put here disppeared)

[Frank Menser]

Here is my concern. NOT saying this is what it is, but The size, proportions and the curve of this fossil are much more similar to the sabres on the cat, than the tusks of the walrus.

There is something strange about the way this forum keeps coming and going on my computer. Anyone else having that problem?