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Haravex

Aust cliffs

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Haravex

Ok so some weeks ago I visited a friend in Bristol one of the days he was in work I ventured up north via public transport (which is always good fun especially when the buses run only every hour and stop at 6) so was limited on time a found a few rocks containing some surface but fragile fish scales, having never been there before I really should have thought on to bring some field tools but was a more spare of the moment type of thing, anyway so back home with the blocks and have just started processing them (and by them I mean 1 so far very nervously) by using a bolster and chisel and splitting along the sediment layers, first I was wondering if anyone has any tips on extracting fossils from this type of matrix yes it is limestone however I remember reading somewhere that using an acid such as vinegar can also damage the specimens. However what I have been ding is using a manual tool to very little effect and the dremel, the problem with this is the manual tool just isn't really helping with matrix removal and the dremel isn't chipping the matrix as effectively as I would hope and instead more crushes than chips (yes this is a dremel engraving tool however this vibrates rather than using a pneumatic action) the other thing I have been doing is using a syringe and very weak solution of b-72 protecting any specimens and using small amounts of vinegar on the surrounding matrix however again the amount that seems to be removed by the vinegar is minimal its probably soaking in to the matrix to be honest but I don't want to fully emerge the blocks and damage precious fossils, I understand this has almost become and essay of writing and was wondering if I should post in the preparations forum however I do have a few pieces I was looking for some id help with again first real exposure to fossils that are non dinosaur in origin, and first time ever dealing with this type of matrix. Any help is always appreciated Matt

PSX_20180314_004221.jpg

PSX_20180314_004321.jpg

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WhodamanHD

Hybodid sharks tooth, @JohnBrewer was kind enough to send me some (and I am still sending you that extra package John, I’ve been storing up some various teeth for it) and I was trying to do some similar things. It is annoying because it’s just hard enough to be annoying with a tool but just brittle enough that a wrong move can lead to disaster. I had a multi cusped one, and a dinged the tip off by accident after an hour of delicate manual work. Luckily, With some glue it was repairable, but a major pain. Just takes time and practice. Go slow, you can always take more time but can’t easily go back on a mistake.

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Haravex

Thanks I didn't know hybodus had teeth as I have seen many (and own two) fin's from the the kem kem beds but never any teeth, as for breaking the main matrix blocks apart hammer and chisel is good yes? I realize the last one is a really bad photo I will re take in better light but looks to be a limb bone or maybe rib perhaps?

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WhodamanHD
8 hours ago, Haravex said:

Thanks I didn't know hybodus had teeth as I have seen many (and own two) fin's from the the kem kem beds but never any teeth, as for breaking the main matrix blocks apart hammer and chisel is good yes? I realize the last one is a really bad photo I will re take in better light but looks to be a limb bone or maybe rib perhaps?

Yes, many different types of hybodid teeth exist there (used to be an open access paper that helped with IDs but not it’s all pay walled). The second thing is probably a bone, maybe fish. Can’t go much farther than that. I’ve been told that the best way to  extract teeth is breaking it into hunks and dissolving it in dilute acetic acid for a very long time. Once you see the teeth enough, you can prep them out. Good luck!

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Fossildude19
8 hours ago, WhodamanHD said:

Hybodid sharks tooth,

Did you mean hybodontid? ;) 

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WhodamanHD
43 minutes ago, Fossildude19 said:

Did you mean hybodontid? ;) 

Yes sorry, thanks:doh!:

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Troodon

Jaw from a Hybodus shark from Germany. 

IMG_1320.JPG.977b28adf9770bc181b9b3a65b71d2c2.JPG.fc805c0a7a02761c7348bbde81d84dfc.JPG

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Taogan

When I lived in Bristol I took the bus over to Aust every couple of months and I had problems with prep as well. The matrix is hard and the fossils are brittle to start off with.I found the lesser of the evils was the chemical method, using a bottle of vinegar diluted in a bucket of water and leaving the bone bed in there for weeks, then rinsing them in clean water for about the same time. It can make the fossils even more brittle, but a bit of Paraloid helps.

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Haravex

The dilution of vinegar to water what was the ratio @Taogan? And thanks for the advice how big of blocks would you place in by the way?

 

@Troodon Thats a really interesting photo, also great that it fossilized so well but odd that in the kem kem they dont seem to have teeth, maybe at that point they had some form of cartilages teeth?

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WhodamanHD
1 minute ago, Haravex said:

The dilution of vinegar to water what was the ratio @Taogan? And thanks for the advice how big of blocks would you place in by the way?

 

@Troodon Thats a really interesting photo, also great that it fossilized so well but odd that in the kem kem they dont seem to have teeth, maybe at that point they had some form of cartilages teeth?

They probably do, they just don’t sell them. Very tiny typically, and people won’t spend money on them.

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Taogan

The blocks tended to be about 10cm, about average for hand specimens, I just lined the bottom of the bucket with rock tipped a bottle of vinegar over it then filled it with water and left it. I got plenty of fish and shark bits out that way and occasional reptile fossils.

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Haravex

@WhodamanHDthe only thing I have ever seen come from the kem kem beds is the following image attached I also don' just buy but dig myself and document everything that comes out of each layer and sieve through all the Moroccan sand fill that they dig through.

 

@Taogan thanks for the information how much water would you say you used and any specific type of vinegar? Does it completey dissolve the matrix or make it crumble? Does it damage the fossils the way an acid prep would for example on keichosaurus where it eats away the bone or does it just leave it more fragile either way will probably try this method on a small block see what happens.

 

Edit forgot to upload the image whoops 

PSX_20180314_145859.jpg

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Troodon
2 hours ago, Haravex said:

 

@Troodon Thats a really interesting photo, also great that it fossilized so well but odd that in the kem kem they dont seem to have teeth, maybe at that point they had some form of cartilages teeth?

Probably because I have not seen Hybodus listed in the Kem Kem faunal list of the Aoufous Formation, is it present?  I see hybodontids like Lissodus, Tribodus or Asteracanthus on the list  

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Taogan

It was about half a litre of white vinegar from Tesco in a bucket with about six or seven litres of water. It only took off the first few millimetres of matrix, etching rather than dissolving completely. One thing I remember was that it made the matrix more brittle than the fossils, so a lot of teeth like your Acrodus ( I think it might have been changed to Lissodus, my books are a bit old) could be picked off of the surface using a mounted pin.

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Troodon
1 hour ago, Haravex said:

the only thing I have ever seen come from the kem kem beds is the following image attached I also don' just buy but dig myself and document everything that comes out of each layer and sieve through all the Moroccan sand fill that they dig through

That's an Asteracanthus tooth which is a Hybodontidae

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KimTexan

Does your Dremel spin? Are you using diamond tip attachments? The diamond work the best for me, but then again all limestone is not the same hardness. Some are harder than others.

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Haravex

@Troodon Ah ok I have only ever seen hybodus shark fin advertised and just assumed they where all the same again knowledge of sharks is very limited, I hope to improve on this knowledge in the future.

 

@KimTexan No it does not spin its more of an engraving vibration function, I did get some carbide drill bits that fit into it so I have a range of attachments for finer details.

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Troodon
7 minutes ago, Haravex said:

@Troodon Ah ok I have only ever seen hybodus shark fin advertised and just assumed they where all the same again knowledge of sharks is very limited, I hope to improve on this knowledge in the future.

 

Well I think those Hybodus spines you see sold is another example of uninformed sellers wanting to assign a species name versus a family name like Hybodontid.

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JohnBrewer

As @Taogan has already said Aust bone bed can only really be dealt with with diluted vinegar then Paraloid on the non matrix areas and keep going. Occasionally you can get reasonable chunks of matrix and bone like verts which pen fine. 

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WhodamanHD
6 hours ago, Haravex said:

WhodamanHDthe only thing I have ever seen come from the kem kem beds is the following image attached I also don' just buy but dig myself and document everything that comes out of each layer and sieve through all the Moroccan sand fill that they dig through.

That’s a cool tooth! Tis a hybodontid as @Troodon pointed out, so they do occur there, just hard to get.

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KimTexan
10 hours ago, Haravex said:

@Troodon Ah ok I have only ever seen hybodus shark fin advertised and just assumed they where all the same again knowledge of sharks is very limited, I hope to improve on this knowledge in the future.

 

@KimTexan No it does not spin its more of an engraving vibration function, I did get some carbide drill bits that fit into it so I have a range of attachments for finer details.

Mine spins. I have engraving, sanding, drilling and numerous other types of attachments. Yours sounds like it might work well for taking out chunks of matrix, which is where I have a problem.

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