Messel Fossil Gar

[JUAN EMMANUEL]

Hey guys I came across this fossil on the internet. I dont think this is necessarily fake, but what are the chances this fossil has had some restoration or frabrication done? 

 

[Praefectus]

I'm not seeing anything that suggests restoration. Some better quality photos would be helpful.

[oilshale]

Real, but difficult to tell how much of the bones are real or only plastic impressions are left.  The scales look good, but the complete tail is missing and the jaw is incomplete.

 

This is from a Senckenberg web site:

 

 

"Since the water-containing oil-shale would fall apart if allowed to dry out in the air, fossil specimens need to be embedded in a different substrate, and thus transferred. A specimen – the perch Palaeoperca proxima shown here, for example – is first prepared on one side, which is then covered with artificial resin. After this artificial substrate hardens, the other side of the specimen is prepared. This preparation technique is known as the artificial resin transfer method."

[RJB]

2 hours ago, oilshale said:

 

"Since the water-containing oil-shale would fall apart if allowed to dry out in the air, fossil specimens need to be embedded in a different substrate, and thus transferred. A specimen – the perch Palaeoperca proxima shown here, for example – is first prepared on one side, which is then covered with artificial resin. After this artificial substrate hardens, the other side of the specimen is prepared. This preparation technique is known as the artificial resin transfer method."

Not that I will ever get the chance to do this but this would be a kick to try someday.  Very interesting.

 

RB

[oilshale]

1 hour ago, RJB said:

Not that I will ever get the chance to do this but this would be a kick to try someday.  Very interesting.

 

RB

Pretty easy to do. This method works with almost all soft and not too porous substrates. So not only for Messel but also for Frauenweiler (Oligocene, Germany). Even Green River material (from the split fish layers) could work (here I would not remove the substrate mechanically but with diluted acetic acid). I also prepped these small fish from Frauenweiler with the transfer method.

 

[Harry Pristis]

 

Here is another example:

 

[oilshale]

5 hours ago, Harry Pristis said:

 

Here is another example:

 

The valid name is now Cyclurus kehreri

 

[Harry Pristis]

Thank you!  @oilshale

[caldigger]

Just better hope when doing the "transfer method" the new side you are prepping out doesn't turn out to be the fossil's ugly side! 

[oilshale]

4 hours ago, caldigger said:

Just better hope when doing the "transfer method" the new side you are prepping out doesn't turn out to be the fossil's ugly side! 

This could not happen in Messel - the corpses were embedded very quickly. Both sides are equally well preserved. When splitting, the fossil is often torn through the middle - with a little luck, you can get two perfect sides of the surface of the fossil with this method.

[RJB]

23 hours ago, oilshale said:

Pretty easy to do. This method works with almost all soft and not too porous substrates. So not only for Messel but also for Frauenweiler (Oligocene, Germany). Even Green River material (from the split fish layers) could work (here I would not remove the substrate mechanically but with diluted acetic acid). I also prepped these small fish from Frauenweiler with the transfer method.

Very nice fish Mr oilshale.   I had no idea is was that easy.   Found a Notogoneus about 12 inches a long time ago and had to leave it behind because the rock would have fallen apart.  Wish I knew about this then.  Dang     Can I ask what kind of resin is used?

 

RB

[oilshale]

2 hours ago, RJB said:

Very nice fish Mr oilshale.   I had no idea is was that easy.   Found a Notogoneus about 12 inches a long time ago and had to leave it behind because the rock would have fallen apart.  Wish I knew about this then.  Dang     Can I ask what kind of resin is used?

 

RB

Hi RB,

I'm not sure that the transfer method works with GR, but I would guess so. At least it works with Solnhofen fish. The fossil must not be too thin and you must not prepare it with an air scribe (the vibrations would probably be too strong). But if you dissolve the limestone carefully with acid you can use the transfer method.

 

(Nevertheless not my preferred method with Solnhofen fossils - it is much better to glue the split fish together again and to prepare it from above).

 

The resin used is either a low viscosity polyester resin (similar to Bondo® All-Purpose Fiberglass Resin for repair projects https://www.3m.com/3M/en_US/company-us/all-3m-products/~/Bondo-All-Purpose-Fiberglass-Resin/?N=5002385+3293240937&preselect=8711351&rt=rud ) or a low viscosity epoxy resin. Resins shrink during polymerization (up to several centimeters per meter!). With large fossils it can happen that the resin layer shrinks too much and the compound (slab and resin) bulges and even delaminates.  Epoxy resin has the advantage that it shrinks less compared to polyester resin, less heat is released during curing and it cures more slowly (more time to work with). But it is more viscous and higher priced.

 

I personally prefer polyester resin.

I always use cooled resin from the refrigerator - so I have more time available. It is important to dose the amount of hardener correctly - if too much hardener is used, the resin can become so hot (due to the heat of Polymerisation) that cracks appear.
You first pour the resin onto the fossil, remove any air bubbles and then insert one or two layers of glass fiber fabric into the still liquid resin. This significantly increases breaking strength and reduces shrinkage.

I prepared crocodiles up to 1,5m long with the transfer method (the resin plate was about 2m long, 50cm wide an 1cm thick) without any problems.

Thomas

 

[RJB]

@oilshale.  I can see you certainly know your stuff.  If i was younger I would actually try this but now, I can see its too much work for me.  Now watch me find another fish that needs this!!!  I will be at the quarry's this June. 

 

RB