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cynthia

My first fossil jaw

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cynthia

Hi there,

I'm new to the fossil forum and I am hoping to learn a lot from all of you! I live in Akaroa, New Zealand. This fossil supposedly comes from the Sahara. Any guesses as to what it was? I was hoping for Pakasuchus kapilimai, but that is not likely :D

post-20116-0-65424700-1448083837_thumb.jpg

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jpc

It is a mosasaur from Morocco. Certainly not Pakasuchus, which is from Tanzania and there is only one specimen of it. It is much smaller than this jaw fragment... the skull is only three inches long.

I am intrigued, though... with all the beasties coming form Africa, what made you guess Pakasuchus? I have a close affinty to this animal.

Edited by jpc

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cynthia

Hi Jpc,

Thank you for that! It must be a baby mosasaur. I thought that the teeth looked almost mammal-like and I read that Pakasuchus had unusual teeth and that they were very small. I hadn't realized that Pakasuchus were THAT small.

Do you think my jaw fragment is a Dallasaurus turneri or a very young something else?

Have you seen the skeleton of the Pakasuchus? Why do you have a close affinity with it?

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Troodon

Cannot help you with an ID but the matrix and jaw preservation does looks like something from the Kem Kem beds of Morroco. Nice small jaw.

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LordTrilobite

I'd say it looks like it came from Khouribga, not Kem Kem. Definitely looks mosasaur-ish. For a proper identification I think better pictures are needed. Closeups, sharper and with better lighting.

Nice jaw though.

Edited by LordTrilobite

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cynthia

Thank you! I'll try & take some better photos

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Troodon

I'd say it looks like it came from Khouribga, not Kem Kem. Definitely looks mosasaur-ish. For a proper identification I think better pictures are needed. Closeups, sharper and with better lighting.

Nice jaw though.

Correct actually meant Khouribga not sure why I said Kem Kem

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cynthia

hopefully, this photo is a bit better? If it's a mosasaur, which one?

post-20116-0-88660800-1448135156_thumb.jpg

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LordTrilobite

Well, i think you have a rightside lower jaw due to the jaw piece being so narrow and straight on the bottom.

But I don't really recognise the teeth right away. The shape reminds me a bit of Prognathodon. But they seem really tiny. Who knows, maybe you really do have a baby Mosasaur.

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cynthia

thank you Lord Trilobite!

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JohnJ

Cynthia, I'll play the skeptic. Based on your photos, the likely origin of the piece, and the strange teeth, you may have something concocted of unrelated parts. I don't think a determination can be made from these photos. This one may require an in hand review by someone that knows mosasaur bones. ;)

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cynthia

that's an interesting idea JohnJ...with that thought in mind, I've had a REALLY close look at it under my jeweller's specs. The teeth are definitely attached to the jaw bone. The missing teeth "spaces" are approximately the same area as that occupied by the teeth. Have people "fabricated" this kind of sandstone matrix? If that is common, then the whole thing could be a trump, but it is really consistent with other Sahara sandstone I've seen with vertebrae and teeth, etc. but they might be fakes too. Here are some more shots

post-20116-0-85660500-1448171740_thumb.jpg

post-20116-0-61594200-1448171983_thumb.jpg

post-20116-0-09361000-1448172162_thumb.jpg

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jpc

I am no good at mosasaur genus ID, so I can't help you there.

I wasn't the guy who discovered Pakasuchus, but I did find the skull when we collected it, and I got to prep the skeleton. It was for sure one of my most rewarding and exciting prep jobs.

Yes Pakasuchus teeth are mammal-like. Mammal teeth (except for the canine teeth) have multiple cusps, or points. (see the recent post about Nebraska Micro fossils). These mosasaur teeth are not at all mammal-like. They are simple conical pegs... more reptile-like., but even that is a bit oversimplified. If you have a cat or dog at home...have a look at their teeth... fairly complex,and at your own teeth...also fairly complex.

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cynthia

wow jpc, that is really exciting! Lucky you :D Thanks for the info on teeth...I see what you mean about the variety in mammal teeth. These little "fossilized" teeth reminded me of canines, but they are all the same. Do you have some good photos of the Pakasuchus teeth?

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JohnJ

Yes; that kind of matrix is fabricated often. It's usually a blend of glue and the native matrix. Many examples can be found in this sub-forum.

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cynthia

thank you JohnJ, I'll go have a look

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jpc

wow jpc, that is really exciting! Lucky you :D Thanks for the info on teeth...I see what you mean about the variety in mammal teeth. These little "fossilized" teeth reminded me of canines, but they are all the same. Do you have some good photos of the Pakasuchus teeth?

I do not. The teeth were not well exposed. The best views they got of them were by CT scanning the skull. Heck, I can't even find my pix I took of the project. I think they are all on my work computer. This shows some good pix of the specimen. Yes, I have been pretty lucky over the years.

Edited by jpc

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cynthia

thank you jpc--I would love to find one of these!

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LordTrilobite

I'm going to say that this jaw is 100% genuine. While faked Mosasaur jaws are very, very common. I see nothing suspicious here. It just looks completely real. Fakes have certain tells, none of which are visible here. Even though the photos could still be a lot better.

What might help with the identification, is finding out if the teeth have serrations and if they have ridges on the side or if they are completely smooth. That might eliminate some types of Mosasaurs.

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cynthia

thank you Lord Trilobite,

There are no serrations on the teeth (looking thru my jeweler's headset). They are completely smooth

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JohnJ

The tooth orientation appears to be curved toward the inside of the 'jaw'; typically, there is a curve toward the back of the jaw on mosasaurs. Also, the base of the teeth look strange. "Matrix" covering parts of the teeth on a mostly prepped jaw is usually done to hide unnatural assembly.

I looks like you've removed some matrix on the later photos...?

post-420-0-54636700-1448219282_thumb.jpg

A study of the details on known mosasaur specimens can help you spot inconsistencies on the popularly constructed pieces.

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cynthia

Hi JohnJ,

I haven't removed any matrix from the previous photo. Looking at it again under magnification, the curve of the teeth is towards the back. There isn't much curve, because the teeth are so small! But altho they are embedded, it looks like the inside plane is quite flat and the teeth are centered over the jawbone (not tilting in, when you look at it from the top). Would a definitive test be to wet the matrix and see if it falls apart? Then I'll know if it is a fake?

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LordTrilobite

Don't wet the matrix without stabilising the jaw first. Sometimes Khouribga material completely falls apart in water even if it's completely real. I still don't think there is anything suspicious on this. Imo this is a 100% authentic mosasaur jaw. It's just a question of what species.

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JohnJ

Agreed, rather than wet the whole thing, you might try dipping an old toothbrush in rubbing alcohol and lightly cleaning the exposed surface. Doing so under magnification will help.

After cleaning, additional photos directly from the side would help. It may be that artifacts of lighting could be source of my doubts.

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cynthia

thank you. So especially around the base of the teeth: gently brush with rubbing alcohol? I'm not sure if I'm brave enough!

For clidastes propython the toothed area looks about 20 cm long (that's the only photo with a measurement reference. My little segment is only 6 cm and looks to be the back third of the bottom jawbone, so if I extrapolate the whole thing might be 18 cm. Which seems about right.

I noticed in the photos of clidastes liodontus, that the back bottom tooth is smaller than the more anterior ones. That's what my little teeth look like too. I'm still a bit bothered by the size of my teeth overall--they just seem too small for a mosasaur!

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