sjaak Posted October 23, 2010 Share Posted October 23, 2010 (edited) Hello, I am new here and just posted an introduction message. The big piece was found by me on a river beach in southern France. The river cuts through Jurassic, Cretaceous and Miocene /Pleistocene sediments. I asked people on a Dutch website for advise, but most thought it was just an odd stone. The right piece I found lately and is probably a rhino (or maybe mammoth) phalanx. It's from the Northsea (Netherlands)and dates from the Pleistocene. Maybe it's wishful thinking (which I'm very good at ), but I see a strong similarity. The French piece has a more or less similar shape, but - unlike the rhino phalanx - not a clear bone structure. If it's a fossil, perhaps a pseudomorph? Please note the piece is "rolled" into a river. Please also note the similar "brownish colour" on the concave part on top (last picture). If it really is a fossil phalanx, then it was a very huge beast. I'm curious what you think of it. On the same beach I also found another piece with a less clear bone shape and a stone structure. Someone told me about fossil bones in rivers that look like rocks due to the fossilation process and the river erosion. As I live in the Netherlands I am not familiar with such fossils (we do not have much rock over here ). Maybe you can help me. PS the scale is in centimetres. Best regards, Niels Edited October 23, 2010 by sjaak Link to comment Share on other sites More sharing options...
tracer Posted October 23, 2010 Share Posted October 23, 2010 i see nothing wrong with your thinking. i don't know enough to say more regarding what it could be, but it does look like pseudomorphed bone to me, and the morphology does appear similar to your comparison piece. Link to comment Share on other sites More sharing options...
Harry Pristis Posted October 23, 2010 Share Posted October 23, 2010 Both objects appear to be stream-rounded rocks. http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
sjaak Posted October 24, 2010 Author Share Posted October 24, 2010 Both objects appear to be stream-rounded rocks. Hello Harry, The little piece is a bone for sure. The big piece could be a stream-rounded rock, but I find the similarity striking. Best regards, Niels Link to comment Share on other sites More sharing options...
Harry Pristis Posted October 24, 2010 Share Posted October 24, 2010 Hello Harry, The little piece is a bone for sure. The big piece could be a stream-rounded rock, but I find the similarity striking. Best regards, Niels If you think that only the larger object is a rock, Niels, exclude it from your next images. By doing so, you can provide good close-ups of the smaller object. http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
tracer Posted October 24, 2010 Share Posted October 24, 2010 sometimes it's very difficult to tell whether there was an original organic origin to what is currently a "rock", particularly if it's from a location where things mineralize and pseudomorph differently from what you're used to seeing. sometimes i get the magnifying lenses fully into play when trying to pin down what i'm looking at. but quite a few rocks didn't start out as rocks... Link to comment Share on other sites More sharing options...
bear-dog Posted October 24, 2010 Share Posted October 24, 2010 tracer for MOTM again . :jig: Go tracer. Bear-dog. Link to comment Share on other sites More sharing options...
sjaak Posted October 24, 2010 Author Share Posted October 24, 2010 @ Harry, here are pictures of the little piece. As you can see this is bone. I also posted three pictures of another less eroded phalanx. Please note that the little pieces are Pleistocene and from the Northsea, while the big (stone) piece is of unknown times and was found more than 1,000 km away in France. @tracer, this is very interesting. I am not used to these kind of fossils. Do you have more information on pseudomorph bone? Question is, if the big piece is indeed a fossil phalange, from which beast? Link to comment Share on other sites More sharing options...
tracer Posted October 24, 2010 Share Posted October 24, 2010 don't know what the big thing could be from. my point on the "rock" thing was that i've seen numerous different types and levels of "fossilization", and i've come to realize that at some point, quite a few "fossils" cross over the line to where they have no organic material at all left, and sometimes they cross over to not even having any trace of original structure left, and then they truly are just "rocks" because they can't be identified as anything else. but if you see enough of it, sometimes there's a little bit of structure left and you can recognize it was once a bone, even though there may not only be no remaining organic material, but also none of the original hydroxylapatite mineral left. i've got "bones" which are simply chert shaped like the original bones, or purely pseudomorphs. Link to comment Share on other sites More sharing options...
Harry Pristis Posted October 25, 2010 Share Posted October 25, 2010 Well, Neils, I'm glad we could sort that out. Big object...rock; smaller object...proximal phalanx (of a wooly rhino, you say). Sounds right to me. Except the use of the term "pseudomorph." I think of the degree of mineralization like this: --not mineralized . . . only the original bone-minerals present. --mineralized . . . mineral infiltration of the original bone-mineral crystal latticework. --permineralized . . . mineral replacement of the bone-mineral crystal latticework. --pseudomorph . . . complete mineral infiltration of the interior and replacement of the bone exterior. That's how I organize these term, and your experience may vary. I can't remember ever hearing a bone described as a pseudomorph. How could one be certain that the mineralization and replacement were complete! http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
tracer Posted October 25, 2010 Share Posted October 25, 2010 diagenesis and permineralization happen, somebody's gotta talk about it, and who you gonna call? read the abstract, puhlease quartz after apatite. as far as determining complete replacement, all i can say is that you'd have to see and hold some of this stuff, but i don't experience doubt that there's no "bone" left in some of it. besides i pretty much never feel obligated to qualify each and every reference i make. i can't be certain that the initial "bone" is really "bone" either, since it might have a speck of fly saliva on it or something. oh, here's a giant, weird (cuz i posted on it) thread on the subject from last year. link Link to comment Share on other sites More sharing options...
sjaak Posted October 25, 2010 Author Share Posted October 25, 2010 (edited) I have attached some USB microscope pictures of the big piece. Not sure what to think of it.... (sorry for the poor quality) Edited October 25, 2010 by sjaak Link to comment Share on other sites More sharing options...
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