White River Rhino Skull Prep

[LordTrilobite]

Today I got this mostly complete Subhyracodon skull from the White River formation, South Dakota. Right now it still looks a bit rough since it's been crushed a bit and there's a bunch of sediment stuck all over the place. The specimen has been pretty well stabilised. So it's not very fragile thankfully enough. Almost all the teeth are present. Only one maxillary tooth is gone and the very tip of the premaxilla is gone. The 2 posterior premax teeth are still there, but the anterior ones are gone. Roughly half of the braincase is also missing on the back of the skull. Otherwise the skull is quite complete.

 

Initial unpacking.

 

Starting prep outside

 

 

After some exploratory prep using dental picks. I will likely start removing much of the bulk of the matrix in areas such as the orbit and nares with powered tools. The different isn't very visible right now since I was mostly working on small areas and further cleaning up areas where bone was already mostly exposed.

Stay tuned for more!

[RuMert]

Looking forward to seeing it finished

[LordTrilobite]

Some more progress today. I've been removing a bunch of material mainly from the orbits on both sides.

[RJB]

Youve just reminded me that ive one of these in a huge jacket that ive got to attack someday.  Cool fossil.

 

RB

[LordTrilobite]

Some more progress from Friday.

 

[LordTrilobite]

I made a little more progress. I've been cleaning the teeth a bit more. Besides the one big missing tooth and one broken one in the back th other teeth are in pretty good condition. They're emerging pretty nicely from the matrix.

 

And a little more progress.

[Ruger9a]

2 hours ago, LordTrilobite said:

I made a little more progress. I've been cleaning the teeth a bit more. Besides the one big missing tooth and one broken one in the back th other teeth are in pretty good condition. They're emerging pretty nicely from the matrix.

 

 

And a little more progress.

Nice work so far!  Thanks for keeping us posted.

[LordTrilobite]

Some more progress. I've pretty far digging out the orbits. I'm leaving some matrix behind the eye under the zygomatic arch since it would be quite fragile otherwise. The whole skull is very squished. But there is also some shearing going on. Most notably in the back of the skull that can be clearly seen on the forehead. But on the front of the skull part of the snout is also moved around. But here there is more matrix between the bones. Besides some fairly thin layers of hard glue, the matrix under here is really soft. I think this break might be fairly recent as the matrix is basically just dried mud at this point. So I'm gonna remove that whole front part, clean the breaks and hopefully put the bone back into it's original place. In the photos I haven't removed anything yet but I've done some cleaning around the edges of the breaks.

[ParkerPaleo]

Nice work so far!

[Ruger9a]

That's quite a task, I can hardly wait to see the finished results. 

[LordTrilobite]

Another update.

 

As I said before. The front part of the skull was misaligned and there was enough soft matrix in the cracks that I could remove this section completely. So part of the nose and front of the jaw are now completely separated from the skull. This also allowed me to more easily clean out the nose area from matrix.

 

Having much smaller pieces separate I wondered if I could dissolve the sediment in water while leaving the bone intact. The matrix is basically really hard caked mud after all. I had a few tiny bone fragments with some sediment attached. I then used those as experiments to see if it yielded good results. Depending on the type of fossil, submerging in water can have disastrous effects on the bone. But this seemed to go really well. The bone stayed nice and strong while the matrix mostly either dissolved or became very soft.

So I scaled up the experiment and tried it on part of the nose that I had removed from the main skull piece. And again this turned out really well. Since it's fairly thin bone and there were already old cracks present the bone did break in a few places in the process of manually removing the now softer matrix. This wasn't a problem though, since all the pieces we big enough and the breaks were clean. After glueing all the pieces back together I have a much cleaner piece of the nose that would otherwise have taken much longer to prep.

 

Having removed the front bone pieces I had much better access to the rest of the nasal cavity. So I've been prepping away at that. I might still remove a bit more. And I will only glue back the bones in their original place when I'm completely done with the rest of the prep, as those bones are now much more fragile with little to no matrix supporting them.

 

With such good results on the nose I decided I would also dip the bigger piece of the jaw under water. This, also worked really well. At this point I've removed much of the matrix other than some in between the two jaw halves for support. The erupting incisor teeth are now also better visible.

[JohnJ]

A less risky option than the longer drying time of water would be rubbing alcohol.  That aside, your reconstruction should look great. 

[Ruger9a]

Very nice work!!  The pieces came out awesome.  I hope everything fits back perfectly.  I can hardly wait to see the finished product! 

[LordTrilobite]

Thanks! And yes, the pieces already fit much better than they did at the start.

[Ruger9a]

That's great!!!!  As long as you don't rush it, I believe it'll turn out wonderful.  

[LordTrilobite]

Alright I'm mostly done now.

Here are some photos from a previous state that I forgot to post. At this point I finished most of the heavy work of cleaning out the nasal area, eye sockets, braincase and smoothing out the remaining matrix that is still in place for stability. I've also filled in some matrix with some spare pieces as there was a gap there. The bone is gone in that area so roughly filling it up with matrix makes it less noticeable. While cleaning the back of the skull, sadly I did not find much of the underside of the braincase. It seems to have mostly exploded when the skull was crushed.

 

 

And this is what it looks like now. I've glued back the nasal bones and premaxilla. Having cleaned out the break surfaces they all fit much better now. There used to be quite an offset before. And having had those pieces separate allowed me much better access to clean out the whole nasal area. It will of course be much more fragile now though. So I plan to make a display stand so that I can show it off properly. So stay tuned for that.

 

[Randyw]

Looking great!

[Ruger9a]

1 hour ago, Randyw said:

Looking great!

Ditto.................

[brad2274]

Very nice, any plans for a mount to display it? would look killer floating 

[LordTrilobite]

10 hours ago, brad2274 said:

Very nice, any plans for a mount to display it? would look killer floating 

Yes I bought some plexiglass that I plan to make some supports out of. I will make a base as well. But I haven't completely figured out how I want it to look. But yes, it will most likely be a floating style with transparent supports.

[LordTrilobite]

Aaand it's done! Now the rhino skull sits on a custom plexiglass stand. I kinda messed up a little on glueing the two parts together, so the join is not as clean as I would like. But overall I'm quite satisfied. Perhaps I will revisit the stand at a later date once more.

Now it's nice and stable in any case and the teeth can be viewed clearly too.

[ParkerPaleo]

Looks awesome!  I'm always amazed at how much crushing there is in some of these skulls.  

[Ruger9a]

Wonderful job!!

[LordTrilobite]

Thanks!

[Sjfriend]

Very good work!