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Aurelius

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I got this jaw in the post today. It's 26 inches long, and seems to be the upper left jaw of a large-ish mosasaur, perhaps Prognathodon?

 

The teeth don't provide much of a clue, since the crowns are, sorry to say, all added in afterwards. I knew this when I bought it, and I paid what I consider to be a fair price for a jaw of this size with botched-up teeth. My aim is ultimately to extract it, and mount it. At that point, I can sort the teeth out to a better standard, and replace the worst examples.

 

I'm interested in any thoughts about the jaw in general - whether you see any obvious signs of tampering or anything unusual. I really wish people wouldn't interfere with these fossils to begin with!

 

Thanks.

 

 

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To start with, the jaw itself looks real. All the bone looks correct. It looks to be a complete left maxilla too.

I agree that it looks like Prognathodon sp., but as you say, if all the teeth are composited in, that would make an ID harder.

 

But, I don't think all the teeth are composited in. Some definitely are, Ive numbered the teeth so it's easier to talk about them. I think especially number 7 looks the most suspicious. But the teeth numbers 8 and 9 look like they might be original. Number 3 and 4 also look like they might be original. And number 11 isn't what I would expect from a composite, so I think that one belongs there as well. I am unable to tell from these photos, but it looks like 6 might also be original.

 

So in summary, I think 3, 4, 6, 8, 9 and 11 might be original.

 

Behind number 10 there seems to be another bone that doesn't belong with the maxilla. That might be interesting as well. And it also looks like there's a large part of a disarticulated skeleton of a fish scattered around the block. There's an enchodus tooth lodged in the jaw between 2 and 3 as well.

 

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Olof Moleman AKA Lord Trilobite

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Nice jaw! Congratulations. Looks fantastic :)

"Faith is to believe what you do not see; the reward of this faith is to see what you believe" - Saint Augustine

"Those who can not see past their own nose deserve our pity more than anything else."

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  This January im taking along my Opti-visor #5 to Arizona.  Gunna be checkng out moso material real close-up this time.  Nice jaw by the way!

 

RB

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There's nothing unusual about this jaw, nor do I see signs of tampering.

 

How did you know the crowns were all added in?

Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday!

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Thanks for the replies, I appreciate it.

 

Whilst I'd love it if even some of the teeth were original, I don't think they are. I think perhaps the photos weren't high enough resolution, combined with the fact that the teeth have been added in quite well. From a distance, you'd be hard pushed to find much fault with them, unlike some of the examples you see.

 

I enclose close-ups of the teeth Lordtrilobite said he felt might be authentic.

 

This one looks quite rough at the join between the crown and the root.

 

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This one seems to have a very plaster-y join.

 

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This one is much better, but it looks quite gluey.

 

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These joins don't look very convincing to me up close (although they are good at a normal viewing distance)

 

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Okay that's very interesting.

 

3.

This one is hard to tell. On the middle and left there does seem to be some filling. Either that or those horizontal scratches are prep damage. But on the far right of the join between the crown and root there does seem to be some part that looks genuine. So what I'm hoping is that this is an original tooth that was just partially repaired.

 

4.

Yeah, I agree this one definitely looks fake. Especially on the left it's really obvious up close.

 

6.

Yes, there is some tampering on this one as well. But the root does seem to extend quite far. On the middle left there is some filling that is spilt over the crown. As a result, this one looks like an easy one to prep. Might be a good place to start and see how extensive the tampering is.

 

8.

Yeah, fake. It looks all smudgy and the root seems to go into the matrix further while the crown doesn't seem as deep. There is a discrepancy on the right of the join where the crown doesn't seem to match.

 

9.

This one looks all smudgy as well. I think I can even see something that looks like a fingerprint.

 

 

So if these are the most convincing ones, then yes, I think you are right in saying that they might all be composited in, sadly. Are you going to post the prep process? It would be interesting to see what the result would be.

Olof Moleman AKA Lord Trilobite

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I think you are spot on Aurelius. Im no expert by any means, but its fairly easy to see what you are saying with those close up photos. but still, a nice piece.

 

RB

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Excellent photography. Such detail is obviously very helpful in the Forum's efforts. I wish all posters had the equipment and skill to present their posts in such a lucid, graphic manner.

Human beings, who are almost unique in having the ability to learn from the experience of others, also are remarkable for their apparent disinclination to do so. - Douglas Adams, Last Chance to See

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Thanks for your comments. I fell in love with this piece the moment I saw it, replacement teeth or not! 

 

@LordTrilobite - I will document the prep process, but it won't be for a short while. I'm hoping to move house soon. My current home is tiny, and I wouldn't have the space to prep a monster of this size.

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  • 3 weeks later...

As a little addendum to this, I recently obtained this jaw, which I thought might possibly be the opposing jaw to the one in my original post. I know it would be impossible to prove definitively, but they are very similar (right down to the teeth, which have had the crowns replaced in exactly the same way as the original jaw, and using the same type of filler). This one is crushed near the snout, which might explain why it's a few inches shorter.

 

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Are they from the same seller? Technically it's possible, however unlikely. As it happens, I have actually at one time bought two separate jaw pieces of a Prognathodon from the same seller that turned out to be from the exact same individual. I was able to confirm that my two pieces were from the same individual because they were two parts of the same dentary and matched exactly. But without an exact match, there is not a lot of hope of finding out if they belong together.

 

What you could do though, for starters, is compare the size. See how they match up. Do the number of tooth positions match? Do the foramina match? Is it even the same species? Are the replacement teeth in the same position around the roots?

 

 

Olof Moleman AKA Lord Trilobite

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Yes, it was the same seller, and I know that he obtained both specimens at the same time. There's just under 4 inches between the two jaws, the newer being smaller, but I think that could be accounted for by the crushing to the front. The roots are exactly the same size, and I suspect there were the same amount of teeth - but I will have to confirm that when I prep them both. I'm pretty sure they must be the same species at least, they're just too similar for it to be otherwise, although goodness knows what I'll find when I start the prep process!

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Yes, prepping will likely give you more information. If you plan on reconstructing the jaws into their original form you might be able to more properly judge the size as well. But keep in mind that similar size and similar preservation does not mean they nessecarily belong together. Though I don't know about Khouribga, some fossil locations have biases for certain sizes of animals. There can be multiple similar sized animals around the same area for all sorts of reasons.

Olof Moleman AKA Lord Trilobite

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  • 1 month later...

Little addendum to this post - I did a bit of exploratory prep on the second jaw, and the whole thing basically popped out of the matrix. I just dug around the top of the jaw (the bottom, in this photo), got my hand behind it, and gently pushed it out.

 

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I'm not sure what to make of it. It came out in two large pieces, which I've glued together. I'm not sure, but I'd assume that this could be a sign that the whole jaw (which, apart from the crowns, is certainly genuine) was placed in a block of fake matrix with a fake jacket. I can't imagine that it should be this easy to get it out, although it is a very solid piece.

 

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The matrix, beneath the first inch (which is very hard) is extremely dry, sandy and easy to break up. I suppose this could be explained by the entire top of the block being treated with some sort of glue solution to harden it. There were numerous fish bones and small shark teeth in the matrix.


The jaw is 3 inches thick at the widest point, although the tip on the left is smaller. I was wondering whether this could be a crushed or martial pre-maxilla, with part of the actual jaw bone missing? I might be imagining that.

 

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I don't think you have part of the premaxilla. If you look on the photo from the side, on the bottom you'll see a dent, which is part of the nares where the nostril would be. So the premaxilla would be more towards the front. I think it might just be an almost complete right maxilla.

Olof Moleman AKA Lord Trilobite

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Looking at the photos of the first piece I suspect some restoration to the bone material as some looks to be sanded smooth above left side tooth.

Overall still a nice display piece.

 

Mike

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4 hours ago, Mike from North Queensland said:

Looking at the photos of the first piece I suspect some restoration to the bone material as some looks to be sanded smooth above left side tooth.

Overall still a nice display piece.

 

 

I think that may be an artifact of the photo. I think what you're seeing is where the "preparator" (and I use the word quite wrongly) has smeared plaster up onto the jaw for their fake 'root'. 

 

I agree that this is a nice display piece. In fact, for what I paid, I am over the moon with it. My aim is to extract it from the block, tidy it up a bit, and (using other similarly sized pieces) create a composite set of jaws. And the skull, if I can find one. The skull material is harder to come by. The fact that the teeth are fake, whilst intensely annoying, at least makes it affordable.

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