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Ludwigia

Preparation of a Choffatia sp. Ammonite

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Ludwigia

I was out at my favorite spot in the Wutach Valley again on Tuesday and dug up a large one this time. It was in a huge block buried under a foot of dirt, leaves and rubble and first I thought that I'd struck bedrock, but that unfortunately didn't turn out to be the case. The area I'm exploring is an old landslide in the woods on the side of a small mountain and although I've found at least one spot where I can start following the bedrock layers up and down, I'm discovering more and more that the whole slope is just full of landslips and floes at various levels, so it's hardly possible to get your bearings in the horizontal and you just have to rely on luck and your nose. Anyway, I was quite struck with the size of this thing although I couldn't make out much due to the surrounding matrix, so I trimmed it down to a size that would fit into my knapsack and trudged back to the car with it. I spent a good 10 hours working on it over the last few days. Here are a few before pics. Front & back and you can just make out part of the keel in the last one.

 

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So I got down to trimming at first with the air pen. It went fairly well, since there was a good parting layer between matrix and fossil. The innermost whorls were unfortunately not there and I inadvertently punched a hole in it with the stylus. I fixed that up later with some stone meal. I placed a ruler in the first photo to show its size.

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I left a thin layer of matrix over the fossil, so as not to scratch it with the stylus. You can now see where part of the keel is broken off at the bottom in the first picture. I could have done some reparation there later with apoxy putty, but I'd already decided at this point to leave it as is, since it provides an interesting glimpse into the mineralized septa. The next few hours were spent mostly abrading with the odd swing back to the air pens to trim off some more excess matrix where it was possible. That was necessary to save some time, since a lot of the remaining matrix turned out to be quite hard and although I was working with 90psi it was still pretty slow going.

 

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Oops. Just run out of MBs. Have to move on to the next post.....

 

 

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Ludwigia

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And here's the finished product after coating it with a beeswax finish. A view into the septa with calcite crystals is in the last photo.

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The interesting thing about this fella is that, although it has a diameter of 30cm., it is only the phragmocone. Half a whorl is missing at the top on the outside from left to right. Just for fun I used my paint program to sketch it up to its projected full size. Not very artistic, but it suits the purpose. The arrow indicates the end of the phragmocone and beginning of the living chamber. This ammonite could have had a diameter in life of up to half a meter.

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Innocentx

Impressive!  Looks very fine.

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Ptychodus04

Roger, this guy would have been a monster! Well done on the prep. 

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ynot

Nice find.

Luving the geode part.

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RJB

Well Roger, after reading all that and seeing what youve done, Id have to say you are a man of patience and a man of talent!  Very nice job and good call on not repairing that part of the keel. 

 

RB

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Ludwigia
19 hours ago, Innocentx said:

Impressive!  Looks very fine.

 

6 hours ago, Ptychodus04 said:

Roger, this guy would have been a monster! Well done on the prep. 

 

5 hours ago, ynot said:

Nice find.

Luving the geode part.

 

Thanks, Guys :)

 

5 hours ago, RJB said:

Well Roger, after reading all that and seeing what youve done, Id have to say you are a man of patience and a man of talent!  Very nice job and good call on not repairing that part of the keel. 

 

RB

 

Makes it all that more interesting, doesn't it? Thanks for the compliments, Ron :)

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JohnBrewer

Hey Roger, how you saw the ammonite in the first place baffles me! Superb work with the air pen as always :dinothumb: however a little more practice maybe needed with ink pen :D

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RJB

however a little more practice maybe needed with ink pen :D

 

That johnBrewer bloke is one funny guy. 

 

RB

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Ludwigia
On 23.4.2017 at 11:42 PM, JohnBrewer said:

Hey Roger, how you saw the ammonite in the first place baffles me! Superb work with the air pen as always :dinothumb: however a little more practice maybe needed with ink pen :D

 

On 24.4.2017 at 5:48 PM, RJB said:

however a little more practice maybe needed with ink pen :D

 

That johnBrewer bloke is one funny guy. 

 

RB

 

I'm taking a sketching course right now, so there's still room for improvement :P

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JohnBrewer

Yeah. I'm rubbish with an ink pen and my prepping pen is worse!

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