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ParkerPaleo

I was recently out vacationing in Wyoming and spent Saturday morning (7/24/21) hunting in the badlands.  As I sat down to rest for a moment, I looked down and saw what I thought were a radius/ulna pair from a small mammal.  Upon closer inspection, it was a pair of lower jaws freshly exposed on the edge of a nodule and on the backside, a small skull.  Needless to say, I was ecstatic.  I spent a bit of time making sure the specimen was consolidated (Paleobond Penetrant, wish I had brought some 4417) and packed it up for the trip home. 

 

IMG_0022.jpg.83da17af50f840cd65fc5ae3804a029f.jpg

 

IMG_0020.jpg.64c6c7629b2d81766ce2f96368b4fe70.jpg

 

I was thinking it would make a great Vertebrate Fossil of the Month but as I am unsure of my identification and being a skilled preparator, I thought it would be more interesting to show the process.

 

I do suspect the specimen to be the marsupial, Herpetotherium fugax.  However, without seeing the teeth, this is mostly a guess.  I do have another specimen with a similar endocast which is what I am using as my basis for an identification at the moment.  Though I am quite unsure if the endocasts of the Insectivores have the same character.  Pardon my anatomy if I get this wrong but there is a fold between the parietal lobes and the occipital lobe that you can see in the above photo and that is what I'm guessing my ID on.  Once we get the teeth exposed, we will know for sure.

 

Here are the pieces on my desk with some better lighting and measurements.

 

A bit of cranium on the negative.

IMG_2533.jpg.758f688e68c78512d6c3bf923c244294.jpg

 

The top of the skull.

IMG_2530.jpg.20ba0edf09575e398119ac4d5af054cc.jpg

 

And the lower jaw that was seen exposed.

IMG_2534.jpg.3c11851c0ecf64cd009fa381121e4025.jpg

 

The plan is as follows:

1.  Clean the blocks of any mud/loose chips

2.  Glue the blocks solidly back together

3.  Bulk matrix removal with pneumatic tools (ARO/Paleotool Microjack-3)

4.  Fine matrix removal under a scope/micro abrasion

 

I'll write up each step as I progress.  Enjoy!

 

And @jpc  I apologize for not visiting you, but it was a whirlwind trip.  I'll catch you next time!

 

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ParkerPaleo

A bit about tools.

 

Here is my microscope setup.  I would hate to think of anyone attempting a specimen this size without a scope.

 

I use a Bausch and Lomb StereoZoom 3.  I have 2 sets of oculars, 10x and 20x.  The zoom ranges from 1x to 2.5x.  The scope is suspended from a boom arm.  One the bottom of the scope, I typically have a 1/2x field multiplier (this reduced the magnification but extends the depth of field so I have room to use tools beneath the scope).  And finally, I have a LED ring lamp clamped around the field magnifier.

 

IMG-2543.thumb.jpg.369c97a080f1178f8c30935896538867.jpg

 

For hand tools, I have a set of pin vices.  The carbide needles were fabricated by Paleotools.  

 

IMG-2544.thumb.jpg.11a41c78dff6766095223bc310fe5c37.jpg

 

I'll show my workbench, Swamblaster and pneumatic hammers when I get to that step.

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ParkerPaleo

Day 1, step 1!

 

My goal for today was to assemble the block.

 

I started by examining each block under magnification to see if anything was loose.  Then used a toothbrush and water to remove any dirt from the edges of the block.  I do want to stress that putting water directly onto the specimen is a no-no.  I used a paint brush and a pin vice to clear any debris on or immediately adjacent to the specimen.  The reason for this is that water is very invasive and will float bit of bone away without you realizing it. 

 

During this process, I did discover a single premolar from the lower jaw was free floating.  It had broken between the joints of the block.  I was able to pick it up on the head of a pin, place it back in the jaw, and glue it down.

 

Stray premolar, I found it on the adjacent block but moved it to this side as I could find a better fit.

 

IMG-2540.thumb.jpg.91dab9308c93bc17bec9689b04d3c7af.jpg

 

Glued down:

 

IMG-2542.thumb.jpg.10c2559d25be8980967e7a0daf5479b8.jpg

 

I had to use a micro pipette and a pin vice to move the tooth into position and glue it down.  Controlling where glue ends up is important on a specimen this size.

IMG-2541.thumb.jpg.35f7dd8c6e038548faa6ee72309e6eb9.jpg

 

After everything was dry, I glued the piece back together.  I used Paleobond PB-100.

 

Assembled block:

 

IMG-2546.thumb.jpg.74e1311384f9a9cee945abf71faf1b1e.jpg

 

 

And here with a scale.  The lower jaws were the only thing exposed in the field. 

 

IMG-2545.thumb.jpg.85a5f33787a65ce752bd033d71f18753.jpg

 

Next prep session, we will start roughing the block out and removing some of the excess matrix.

 

I also did look around in the blocks for indications of other skeletal elements but could not find any.  Would be nice if I owned a CT scanner to be sure  :)

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Wow I’m jealous! Can’t wait to see the next installment!

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ParkerPaleo

More tools:

 

Here is my prep bench in the garage.

 

IMG_2555.jpg.fd60d98d84c85a08224334bcb5c60058.jpg

 

This is a hand built dust box.  Nothing crazy about it other than the size.

 

IMG_2556.jpg.af8b65a526554d30836afcf3799faae8.jpg

 

I own two Swamblasters, this is the LV-1 model currently hooked up.  I also have a MV-1.  I will need to swap to the smaller, more controllable MV-1 to work on this skull.

IMG_2554.jpg.c230c2e4bac20f3189d39f1af1f270d4.jpg

 

Here is my dust collector.  I bought a large cyclone from a wood working supply company.  If my dust box were smaller, I could have gotten away with a smaller cyclone.  That being said, it filters a large amount of the dust and keeps the actual dust collector without much in the bag.

 

IMG_2558.jpg.cef6e769df8b744bfd4c162d51c27dd5.jpg

 

My trusty 20 gal compressor, there is a fair amount of piping and wiring behind the workbench to filter the air, move it where I want it, get power to the right places, etc.

 

IMG_2559.jpg.53cedaccaef46113919134d7c0777fbb.jpg

 

And finally, the air tools I am planning to use.  On the left is an Ingersoll Rand 8315 and on the right is Paleotools Microjack-3.  I've had both for ~20 years.  They are very reliable and precise.  I have broken them down completely and rebuilt them in the past(same goes for my Swamblasters).  Keep care of your tools and they will work for you for a long long time.  :)

 

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ParkerPaleo

Day 2, step 3?

 

Having assembled the block yesterday, I was looking to rough prep the block.  For this I am using the 8315.  The goal here is to remove material far away from the specimen.

I wanted to remove 'triangles' of material to get the block to a workable size and reduce the depth of matrix over the skill.

 

My plan is to come down on top of the cranium and then work around underneath.

 

A quick picture from the workbench 

 

IMG_2561.jpg.02bf73aeabef9de1ef1ecdf9caf6d8ba.jpg

 

And here on my desk a bit later.

 

IMG_2563.jpg.88e06c132c37bf8a650c46ced0133eb8.jpg

 

I left a little pencil mark roughly where the back of the skull is so as not to lose track of it in the assembled block.  I know that the top of the cranium is at the seam above, so we have a few millimeters to go before we reach it.

 

The plan for the next prep session is to continue removing matrix but as we are getting closer to bone, I will switch to the Microjack.

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Looks like a lot of fun.  Amazing how small that is. 

 

RB

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FossilDAWG

Thanks for the very detailed documentary.

 

Don

 

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Ludwigia

:popcorn: :D

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ParkerPaleo

Not much time today but I did want to thin the block a bit and find the edge of the specimen.

 

I started with the ARO and just took layers, millimeter by millimeter, from the block coming down on the cranium.

 

IMG_2573.jpg.4cb1ac26e649420980083ffe086a4d32.jpg

 

Periodically, I would redraw where I thought the skull was located based on the other pictures and the small marks I had on the block previously.

IMG_2574.jpg.3a7900628a57bf32261c326a67a89aa9.jpg

 

As the layers got closer to the seam between the two blocks, I caught the edge of the cranium.  I had to inject some glue at this point as the bone looked loose.

 

IMG_2575.jpg.2faf45ca93d9e0c1013d4d3dc8895cbd.jpg

 

And finally doing more cleanup and a bit of exploration with the microjack.  I may just switch to hand tools soon.  The goal here is to remove as much matrix mechanically without damaging the specimen and we are rapidly approaching that limit.  I don't have a scope over my workbench, just at my desk, but I am using magnification via an Optivisor for the portion (5x magnification).

 

IMG_2576.jpg.9f42d70ef64f46e236461dc62fda41a0.jpg

 

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Yo paleo-p.  Looks like you went out with Kent.  I have never done this but I have seen good results from it... before you glue the skull cap back on, use drill (press if you have one) and drill four holes into the block about an inch away from the skull cap, to a certain depth.  These concretion are quite drillable . When you start removing large quantities from the top of the glued skull, you can go fast and furious until the drill holes show up. If you stuff something colorful in the drill holes you can faster and furiouser.

 

great find. Looking forward to the final product

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ParkerPaleo

@jpc  We did.  The White River wasn't the point of the trip but it's hard to resist a day hunting.  I was bringing my little budding paleontologists out to help/experience a dinosaur quarry.  

 

I'll have to try the drill method on another piece.

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LordTrilobite

Ooooh. Looking forward to seeing how pretty this becomes!

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ParkerPaleo

Did a bit of scope prep today to make sure the specimen was consolidated well.  Over my lunch hour I expanded my window over the skull a bit.  I injected more glue as a few fragments were a bit loose.  This made things look a bit dusty as I captured a bit of dust in the glue.

 

IMG_2578.jpg.3762aa03330f10fbdb4699c62a06a11f.jpg

 

And this evening I used the ARO again to moved some 'bulk' matrix away now that I could easily tell what plane the specimen was in.  As small as it is, it can be deceptive where it is going.  I finished up with some more cleaning under the scope.

 

IMG_2579.jpg.603355169ad9eb610b91d2ba3993df79.jpg

 

Coming along nicely now!  The rear of the cranium is a bit of a mess still, there does appear to be a gap between where the bone ended on one block and the reattachment of the cranium bits from the other.  As small as this is, it is common that a few chips flew out when I split it open in the field.  So it won't be a perfect specimen, and I am okay with that, It's still way cooler than anything else I've found recently.  

 

As I'm exposing the specimen now, I'm starting to think more about how I want it to view when done.  I am considering only preparing the left face and leaving the right in the matrix for now.  I'd like to finish this month and doing a full museum prep may be more than I want to tackle right now.

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ParkerPaleo

This evening I worked the block down a bit more.  I am leaving the rear of the cranium for later.  But I did take a large corner off in front of the face so that I could begin exposing it.

 

Worked with an ARO to this point:

 

IMG_2585.jpg.4aaec5cfd0fdcadefeef0a3a2c4d42e4.jpg

 

And then I switched to hand tools under the microscope.

 

IMG_2587.jpg.b6154dc7202e52dc1847afdd02168bb4.jpgIMG_2586.jpg.cb003f5878c9274a94df9c3d1918d582.jpg

 

We are coming down on the canine here.  I'll start working my way back to expose the tooth row now.  I've also intentionally left some matrix at the end of the nose.  This is so that as I work and turn the specimen in my hand, I don't knock the nose off. 

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ParkerPaleo

So last night after working by hand under the scope, I revisited an old thought of getting a 'quiet' compressor to run my Microjack at my desk.  The main requirement for the Microjack is that it needs to run at pressures over 100 and it needs ~1 cfm of air.  

 

Here is what I ended up with...  (claims 2.4scfm@90psi)  There was a slightly smaller version but I didn't want to risk a return.  If I am lucky, the ARO will run off this too.  I'm pretty sure my CP won't run off this setup but maybe I will get surprised.  

 

IMG_2589.jpg.41c20ffa66c204ed39370d2067c14c7d.jpg

 

This runs the tool great.  I tried it for a few minutes last night and the first thing I noticed was water coming out of my tool.  So I bought a water trap this morning and the problem was solved.  I run a water trap in my garage lab so not surprised at all.

 

It is quiet, I can talk over the motor and hear music.  I'm sure if I rolled it into a closet, I would barely hear it at all.

 

And a little more eye candy from the work after setting this up...

 

IMG_2588.jpg.d44475bcf4730d3076795b1d8dc4a90e.jpg

 

I'm not 100% at this point since I haven't counted the cusps on the molars, and not sure I will be able to as the jaws look to be tightly closed, but I'm confident its Herpetotherium fugax now.  I found a very cool scan of one on the internet to compare it to.  http://digimorph.org/specimens/Herpetotherium_fugax/

 

This setup will significantly increase my rate of progress.

 

 

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hadrosauridae

The problem with those small compressors is that it will have to run almost constantly to supply the tool.  Make sure you read the manual about the cycle rate it needs.  Running it in excess of that, will result in rapid death of the compressor.  You can always plan to stop prepping for a few minutes at a time as needed.

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ParkerPaleo

Understood on the cycle time.  I couldn't find anything in the manual but most compressors assume 4-5 cycles per hour.  I find it very difficult to work under a microscope for more than 15-20 minutes at a time without break.  Especially as this isn't my main profession.

 

I'll keep an eye/ear out for it but at the moment I'm not doing more than 2-3 cycles before breaking.

 

Today I did a bit more ARO work to remove a mass of matrix beneath the zygomatic and back of the jaws.  Still continuing to work my way to the back of the specimen.  I think I will start tackling the cranium a little tonight to clean it up back there.  I printed a scale drawing of a Herpetotherium from a paper (citation at bottom) I found.  I then used it as an overlay to draw a rough line of where I thought the zygomatic should be.  I already knew it was along the split in the nodule as I saw it at discovery.  This was to be sure I avoided getting too close with my air tool.

 

IMG_2592.jpg.b8e93fef9b9077da1e0062098737d5a5.jpg

 

And here is the current side view.  It appears that P1 is missing, and the canine has slid out of position, but all the molars appear to be there.  There is room from underneath to see the cusps once I get to the point of air abrasion.

 

65039117720__1207CC3E-E889-4F1E-8755-EBF28B1C988A.jpg.2f9e0d33fb92b408971d160a88c083da.jpg

 

Paper:

 

Horovitz, Ines & Ladevèze, Sandrine & Argot, Christine & Macrini, Thomas & Martin, Thomas & Hooker, Jeremy & Kurz, Cornelia & de Muizon, Christian & Sánchez-Villagra, Marcelo. (2008). The anatomy of Herpetotherium cf. fugax COPE, 1873, a metatherian from the Oligocene of North America. Palaeontographica Abteilung a -Stuttgart-. 284. 109-141. 10.1127/pala/284/2008/109. 

 

 

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ParkerPaleo

Typing up and picturing the progress has given me a lot of enthusiasm to finish this project.  It has been a great deal of fun discovering this piece.  I had some time between meeting today and did some additional work to expose the zygomatic.  I also started cleaning up the edges of the cranium, slow going here, the cranium bone is so delicate.  

 

IMG_2595.jpg.bf8722c99c99b66fdc67c025b8315fa1.jpg

IMG_2594.jpg.9d4e705504c4f153bb3e38ac729d6430.jpg

 

I am beginning to wonder if reattaching the cranium over the endocast was the right call, there are quite a few gaps and just the endocast may have been prettier.

 

Task list of things left to do.

1.  Sculpt/prepare out the eye orbit.  Right now it looks like a mess.  Some sculpting of the matrix in the eye should make it look much better.

2.  Clean up the top of the cranium.

3.  Track the rear of the zygomatic back to the cranium.

4.  Prepare the nose and incisors.

5.  Lightly abrade the tooth row.

 

I was also having some issues controlling the very fine dust that is generated by the Microjack.  I ordered a fish pump and was planning to pass a light stream of air near the specimen to hopefully keep the dust in better control.  I'll add it to the tools pictures if it works as I expect.

 

 

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:popcorn::popcorn:

Looking good! really interested  to hear how the air pump works.. right now I’m using a battery powered fan with mixed results….

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ParkerPaleo
Posted (edited)

So here we are at a stopping point.  I can definitely say the specimen is Herpethotherium fugax now, and that was really the main goal of starting this.  I am waiting to prep further until I can show/discuss it with a researcher.

 

I was able to clean a good amount of glue from the cranium, work here can continue for some time but it is very slow and painstaking.

 

I have not abraded the teeth.  They are smaller than my pin vice so I am avoiding picking on them at the moment.  My MV-1 is a few hundred miles away at the moment.  I did not want to attempt abrasion on something this small with the LV-1.  It's designed for much larger things.

 

The entirety of the zygomatic was preserved, which I find amazing.  I left a good deal of matrix in the orbit to give it strength and stability for now.  I am also expecting this specimen to have a really nice basicranial region preserved.  That's a project for another day though.

 

Here are some better pics of where it is currently.

 

IMG_2606.jpg.2a86ebda08301bde7530b622930c0291.jpg

 

IMG_2604.jpg.5830586397069341d17eb935941dc434.jpg

 

IMG_2605.jpg.b97be1463e46c02e13aee7bdcc178bff.jpg

 

In reflection, there are a few things I should have considered.

 

1.  I should have mentioned a safety tip.  I was working under a scope with an air tool and little ventilation, should have remembered to mask up.  Luckily this is not an everyday job for me and my main lab has these precautions in place.

2.  I should have more closely pondered putting the top of the cranium back on the endocast.  Maybe I would have made the same decision but in hindsight, it would have been better looking if I left the other block off the top.  And saved alot of prep time.  (Didn't track hours but I'm guessing 10-15 hours were expended in this prep so far)

 

I hope you have all enjoyed the journey with me.

Edited by ParkerPaleo
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Looking great! Thanks for taking us on this prep journey with you!

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This was extremely satisfying to read! Great stuff. Living the dream, I wish I could do this.

There is not much point were I live in Belgium, no Fossils like that to be found.
Traveling and then take the unprepped fossil along is a little over the top I think. 

Looking forward to the finished result ! 

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Gotta say this is a very interesting thread.  You do some nice work fella.  Glad to know your gunna start wearing a mask too. 

 

RB

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