Tx Placenticeras Ammonite Restoration Project

[Texas Fossil Hound]

I went out to a site where there was a few weathered Placenticeras Ammonites still in the rock. These ammonites in the layer I was digging them are notoriously brittle and as soon as a good rain comes along would have obliterated them. They were in a gritty gray mud bed of loose heavily fractures sediment. Here is what I did to get them out and restore one suitable for display.

Locating an intact one is the hard part. These are usually already scattered and you only find pieces of these downstream. We located a few and I picked one that looked like it would possibly hold together in a minimal number of pieces through the extraction process.

Extraction

I did not have time to do a thorough pedestal and plaster approach because of the long hike out and the >100 degree temps of the afternoon. I started with chisel and hammer parallel to the fossil around the edges to remove loose matrix and get a lip of the surrounding matrix/fossil exposed around the edges. Because of the natural fracture around the fossil itself, the simple vibrations in the rock popped the entire fossil loose from the matrix. This was not what I wanted, because I prefer to have the matrix attached when extracting the specimen so I can remove it in a more controlled environment.

Regardless, I continued to remove the surrounding matrix and partially pedestal the fossil till I could wrap heavy duty aluminum foil around it in several layers. Before covering the fossil, I took pictures frequently to help me later during the reconstruction process. I pressed the Aluminum foil into the fossil to help stabilize it when I was ready to flip it over. I jiggled a few of the ammonite pieces (it was in many pieces before I started) to ensure it was indeed separated from the matrix below. Once satisfied, I gripped as much of the fossil as I could using both hands to squeeze the loose pieces together and bracing the bottom of the ammonite with my knees to ensure it did not slide when I flipped it. I took a deep breath and turned it over.

I checked to ensure I got the majority of the fossil - Yep! There were several small pieces of both fossil and rock that did not flip with the wrapped fossil. Some were clearly parts of the fossil, but others appeared to just be pieces of matrix. I took all of these and put them in a separate piece of foil - there were maybe 5-8 small pieces. I double checked for any other potential pieces - Nope - then wrapped the rest of the fossil in more aluminum foil. Once it was good and tight, I wrapped this in a heavy towel and stuck it in a backpack to lug it all the way back to the car which was miles away.

At Home Prep

I opened the Aluminum wrap by carefully cutting across the top in an 'X' and peeling back the aluminum foil till it was a kind of aluminum bowl. I took each piece out one at a time and cleaned it with a little water and a medium bristle toothbrush. Some pieces were crumbly in water, so I stabilized these with some thin cyanoacrylate (superglue). I started with the easiest piece to remove and worked around the fossil cleaning and photographing and gluing piece after piece. When I found a piece missing from the assembly, I would stop and look through the aluminum bowl in the location where the piece should be sitting and tried all the small bits till I found the one that fit. If I could not find it there, I would go to the secondary aluminum pouch and go through those pieces. Being methodical and ensuring pieces always remained where they were when the fossil was wrapped is critical to reassembly.

Tools

Water tub for washing pieces, several different toothbrushes for various bristle stiffness, several picks for removing excess matrix, Good light, reading glasses (cause I can't see as good as I used to), towel to avoid small parts bouncing off the table, Thin and thick Superglues - thin for stabilizing and small pieces, thick for connecting big pieces together, and a camera for documenting progress and the location and position of all the little pieces.

...continued pics on next post...

The final result is a nicely restored fossil.

Jon

Edited September 17, 2013 by Texas Fossil Hound

[Texas Fossil Hound]

More pictures of the progress...

Pulling out and cleaning pieces one at a time.

Gluing them together as you go...

Keeping a good position on all small pieces

Lay them out prior to gluing

The final assembly front...

...and back.

The only thing I have left to do is cleaning up some of the glue lines from the little spots where it squeezed out between the cracks. I will use acetone to do this.

Hope this is helpful.

Jon

Edited September 17, 2013 by Texas Fossil Hound

[Dave pom Allen]

nice prep and photos . nice to see someone using the same restoration methods that i do.

[bone2stone]

Patience and a skillful touch yields another classy specimen.

Question: Are you hunting the Eagleford?

Jess B.

[Foshunter]

Jon, Nice prep job------Tom

[PFOOLEY]

Great job on restoring an excellent find! Thanks for the step by step documentation.

[vertman]

Nice report and good ammonites! I, too, am curious as to the geology of the site you are hunting. I am wondering if you are not high above the Eagle Ford, in either the Taylor or Navarro groups. And if you are, I would ask if you are sure of the I.D. on these guys. Is there a chance they could be Sphenodiscus instead?

[Texas Fossil Hound]

Patience and a skillful touch yields another classy specimen.

Question: Are you hunting the Eagleford?

Jess B.

I have not in a long time, but would like to sometime soon.

Thanks for your comments!

Jon

[Texas Fossil Hound]

Nice report and good ammonites! I, too, am curious as to the geology of the site you are hunting. I am wondering if you are not high above the Eagle Ford, in either the Taylor or Navarro groups. And if you are, I would ask if you are sure of the I.D. on these guys. Is there a chance they could be Sphenodiscus instead?

I am going to have to do some map checks to see what formation it is exactly. It is very possible I have the wrong ID on this Ammonite. I could not find a good resource on the Identification. Do you know of a source I can use to help pinpoint the type?

Jon

[Uncle Siphuncle]

Compare sutures of Sphenodiscus to Placenticeras using Akers if possible.

[rejd]

Great prep job. I see you are using cyanoacrylate. I have used it in the past and now I only use paraloid B72. It is much easier to work with and cleans up easier as well. Also it is much easier to redissolve if you need to reposition a piece. Just my thoughts.

[Ludwigia]

Nice job! I collect at a site in the middle Jurassic where I often have to take home jigsaw puzzles and also find as you that aluminum foil is a great help for saving all the pieces in their original positions. Thanks for the detailed documentary.

[Texas Fossil Hound]

Nice report and good ammonites! I, too, am curious as to the geology of the site you are hunting. I am wondering if you are not high above the Eagle Ford, in either the Taylor or Navarro groups. And if you are, I would ask if you are sure of the I.D. on these guys. Is there a chance they could be Sphenodiscus instead?

Vertman,

I am not an expert on ID, but I have a couple Sphenodiscus ammonites with their distinctive sutures. But I am not seeing the same patterns and the keel is not rounded. It is very thin and pointy. I looked at a lot of ammonites online to try to figure it out, but I still may be wrong. I will comment back here if I can figure out a better ID. Thank you for the information!

[donckey]

Great how you explained all the stepps made in recovering and restoring this beautiful ammonite

Thanks for sharing

Peter