abyssunder Posted July 16, 2019 Share Posted July 16, 2019 On 7/15/2019 at 5:30 AM, Plantguy said: Thanks Lori, I should have put more arrows on my specimen photo but yeah the transverse section of mine has an area near the core that has no lines and that was causing me to wonder...probably there but in reading some other posts it looks like sometimes the lines are just more visible along the outer portions of the tusk. Regards, Chris Hi Chris, thank you for your inside. What you said is correct. Classically, measurements of the Schreger lines are done in the dentine-cementum transition zone (with more than one samples) of a transverse section of a tusk to determine the angle between the lines, but those angles decrease from the outer layer to the inner layer (going down to the pulp cavity), also vary in relation to distance along the proximo-distal axis of the tusk. Toward the distal part of the tusk these are reduced to low values. Patterns are also changed. " This means that Schreger angles depend on their location within the transverse tusk section, on the diameter of the transverse tusk section, and also on the location of the section sampled along the proximo-distal tusk axis." (...) The smallest angles, ‘V’ pattern, and longest wavelengths occur near the pulp cavity. Angles become larger, patterns change from ‘V’, through ‘X’, to ‘C’, and wavelengths become shorter towards the tusk surface. " reference: Moravcova, M. (2008). Schreger pattern analysis of Mammuthus primigenius tusk: analytical approach and utility. Bulletin of Geosciences. 83(2) : 225-232. 2 " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
dbrake40 Posted July 22, 2019 Author Share Posted July 22, 2019 Met with Alex from the Science Museum of Minnesota today. He finally had the piece in hand and confirmed his belief that it is indeed the outer layer of fossilized tusk. He also asked to take a carnivore jaw, see image, that we had always suspected was just a coyote. But apparently not - so more to come later on that one! 3 Link to comment Share on other sites More sharing options...
Plantguy Posted July 23, 2019 Share Posted July 23, 2019 On 7/21/2019 at 10:26 PM, dbrake40 said: Met with Alex from the Science Museum of Minnesota today. He finally had the piece in hand and confirmed his belief that it is indeed the outer layer of fossilized tusk. He also asked to take a carnivore jaw, see image, that we had always suspected was just a coyote. But apparently not - so more to come later on that one! That is awesome! Glad you got some in hand/in person confirmation. Looks like you guys have all kinds of interesting stuff. Good luck with the jaw! Regards, Chris Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 23, 2019 Share Posted July 23, 2019 Looks to me like you did paleontology! Fun, ain't it? Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
Markfothebeast Posted July 23, 2019 Share Posted July 23, 2019 (edited) Could it be petrified wood that was carried down during the great midcontinent rift? I don't know. Just throwing ideas out there. I'm not too far away from south MN... Ahh. Read the final result just now. Awesome! Edited July 23, 2019 by Markfothebeast Link to comment Share on other sites More sharing options...
Mark Kmiecik Posted July 23, 2019 Share Posted July 23, 2019 19 minutes ago, Markfothebeast said: Could it be petrified wood that was carried down during the great midcontinent rift? I don't know. Just throwing ideas out there. I'm not too far away from south MN... Ahh. Read the final result just now. Awesome! Been there, done that. Welcome to the club. You've got lots of company here. Mark. Fossil hunting is easy -- they don't run away when you shoot at them! Link to comment Share on other sites More sharing options...
dbrake40 Posted March 22, 2020 Author Share Posted March 22, 2020 A few more images. 1 Link to comment Share on other sites More sharing options...
dbrake40 Posted June 23, 2020 Author Share Posted June 23, 2020 Update on this one. Before I recieved confirmation from my friend Alex at the Science Museum I also sent these photos to the infamous Dick "Sir Mammoth" Mol, a Dutch paleontologist, he also confirmed that is was "the out bark" of either a mammoth or mastodon. Here's his entire reply: Dear Sir, Peter de Bruijn, treasurer of the Dutch working group on pleistocene mammals asked me to answer your e-mail for the identification of a fossil which looks like a fragment of a proboscidean tusk. Yes, I can confirm the identification. It is a piece of a tusk of a mammoth or a mastodon. It is the bark (outer shell, so to say) of a large tusk. It is lacking the so characteristic Schreger lines whih can be found in all proboscidean tusks, except for Deinotheres, because this is not the dentine or ivory but cementum. The outer shell of a tusk of a proboscidean is built up of cementum and not of dentine and has no Schreger lines. I hope this information is of use for you. Yours sincerely, Dick Mol 1 Link to comment Share on other sites More sharing options...
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