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Saurorhynchus, a very rare fish jaw from Whitby, UK.


TqB

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Saurorhynchus acutus (Agassiz, 1844) rostropremaxilla.

Lower Jurassic, Mulgrave Shale Member (bed 42), Falciferum Subzone. Near Whitby, Yorkshire.

 

I spotted this little fish rostrum when I was looking for belemnites a couple of weeks ago. It was about to flake off the outcrop and I hadn't found anything else interesting so I brought it home as a consolation prize.

 

After some research, it seems it's very rare here. The only recorded specimens I can find are a few (5?) 19th century ones, including the holotype which is also just a jaw. Other workers at the time (Tate & Blake) doubted their Yorkshire provenance, assuming them to have been from the Dorset Lower Lias, sold by dealers - a similar species is quite well known from there. 

 

Here's a very recent paper: Saurorhynchus revision.

It is a lot more common in Germany, with more complete material. 

 

I prepped its hidden teeth today  - 5 hours with a scalpel under a x20 binocular microscope. I think an air abrader would have blown them away.

 

IMG_2510.thumb.jpg.e7d6a0f1df192c647ae5f244427de7f3.jpg

 

IMG_2511.thumb.jpg.f808cc56bcc81e11f83076b7b9b215d0.jpg

 

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As found:

 

IMG_2499.thumb.jpg.68ec618aaa1e28aa846a391daa01a8bf.jpg

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Tarquin

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Hey @TqB,  that tip can be repaird and the rest prepped out to expose the rest of those teeth, including making all the other teeth look much better.

 

RB

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9 hours ago, RJB said:

Hey @TqB,  that tip can be repaird and the rest prepped out to expose the rest of those teeth, including making all the other teeth look much better.

 

RB

 

Hi RB, there's certainly room for improvement but it's very fragile. I haven't dared use pneumatic tools on it though I do have an upgraded pneumatic dental descaler which might be up to it.

I really don't know how I'd go about restoring such a thin tip successfully...

Tarquin

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I wouldn't use modern tools on this one, I would get traditional. Nothing wrong with a mounted pin and patience, it gives you a connection to the fossil. Nice piece, I haven't heard of one coming out of Whitby for years.

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3 hours ago, Taogan said:

I wouldn't use modern tools on this one, I would get traditional. Nothing wrong with a mounted pin and patience, it gives you a connection to the fossil. Nice piece, I haven't heard of one coming out of Whitby for years.

 

Thank you, I'll go along with that. I'd be interested if you know of any others besides the ones in the literature - the paper I linked to, published this year, doesn't mention any more modern material from the area.

Tarquin

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@TqB  I think one would use air abrading tools and the right media for this, along with a glue, some 2 part putty with small sculpting tools and colorants for the putty.

 

RB

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@RJB Thanks, that might work although I think my abrader would blow bits off, even at low pressure and with a soft medium. The shale is quite hard and you need something like iron or dolomite powder, bicarb doesn't do anything. Maybe a micro-abrader, if that exists? 

I need bits to practise on but fish of any sort are hens teeth in this rock...

Tarquin

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Thats not good.  Always much easier and much nicer to work on when the rock is softer than the fossil.  Now im wondering if you should even try?  

 

RB

You need @Ptychodus04 to add his input for this.

 

RB

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Thanks for the ping @RJB I missed this threat completely.

 

@TqB I would probably not go after this with abrasives as my experience with U.K. shale is that it is often almost slate it is so hard. It does respond well to mechanical prep with a small scribe (something like the Paleo Tools Micro Jack). I would consolidate the bone before starting.

 

Very nice specimen.

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Just now, Ptychodus04 said:

Thanks for the ping @RJB I missed this threat completely.

 

@TqB I would probably not go after this with abrasives as my experience with U.K. shale is that it is often almost slate it is so hard. It does respond well to mechanical prep with a small scribe (something like the Paleo Tools Micro Jack). I would consolidate the bone before starting.

 

Very nice specimen.

 

Thanks, Kris, that sounds like a good way to go. I use paraloid but haven't put any on yet (apart from one tooth that was already broken). The real problem is going to be the tiny intermediate teeth either side of the main ones that mostly aren't exposed yet...

 

For comparison, here's the 1844 holotype from probably the same matrix - looks like they had trouble with it!

595bce883dfeb_ScreenShot2017-07-02at16_25_37.thumb.png.4a73c82485c971f3eeb20678447fba03.png

Tarquin

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Wow! Yours looks much better.

 

Definitely consolidate before proceeding. I would use a large sewing needle in a pin vise if I didn't have my small scribe. Keep the needle sharp so you don't have to use much force to scrape matrix away. On the small teeth, only uncover the top edge of the entire length. Don't try to prep down the sides or they will tend to break off. Definitely use a minimum of 10x magnification.

 

Go slow and you will be fine.

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@Ptychodus04 Thanks, good advice, I'll do that. My binocular microscope just does 20x but that seems about right for manipulating a needle.

Tarquin

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Just now, Ptychodus04 said:

@TqB I'm sure you will do it justice. If you get in a bind, you can always send it on a Texas holiday and I'll give it some low cost dental work. :D

 

Thank you for the kind offer, wish Texas was nearer! :D I'll get around to doing it eventually, need to schedule some days in the prep shed.

Tarquin

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