Upper or lower jaw ?

[Brevicollis]

Hello, my father bought yesterday this nice mosasaur jaw, now he wants to know if its a dentary or a maxila, as we want to present it in the right position.

Thanks !

[Jaybot]

@pachy-pleuro-whatnot-odon

[Brevicollis]

Hello, anyone got an answer by now ?

[Moth.11]

I'm not an expert on this, but it looks Lower Jaw to me. 

PS. Nice jaw!

Edited December 15, 2024 by Moth.11

[minnbuckeye]

Looks to me like a random bunch of bones with a set of teeth placed in a row not associated with the bones. So in my novice opinion, one can not answer your question based on what is presented in the photo.

[North]

Can you post close up from the largest bone parts, so we can see the texture?

[FB003]

Most jaws I've seen the teeth have looked to be embedded into the jaw vs all the teeth having all the root exposed.  I do not see any sort of physical bone on bone connection from teeth to the bone in these two pictures which to me makes it a little suspect but that could also be the angle. It may benefit to add additional pictures from other angles as North mentioned. Hopefully some mosasaur experts come on to take a look.

[doushantuo]

for comparative purposes

( copyright free image,from DOLLO's  ( " Belgian mosasaurs ")

(They might even be the type specimens of the genera )

Edited December 16, 2024 by doushantuo

[North]

Im more concerned that Im not seeing bone texture seen in mosasaur bones.

On a first look it seems more like bone in this jaw.

https://www.thefossilforum.com/topic/144684-help-id-a-moroccan-fossil-jaw/

 

But should not say for sure without closer look.

[Brevicollis]

I took some more pictures, I hope they will help !
@pachy-pleuro-whatnot-odon, @Praefectus

[pachy-pleuro-whatnot-odon]

I agree with the others here in that this, unfortunately, is a composition. From the rooted teeth having been placed and sometimes created, to bones from a different animal, probably fish, being used to create the illusion of an exploded jaw. Great for display, but little in terms of scientific merit... 😞

[Brevicollis]

@pachy-pleuro-whatnot-odon So, you think that all of the matrix, the whole bonebed, with all sorts of different bone fragments like fish verts, mikro shark teeth, pieces of turtle carapace and shell bits is fake ? I have seen fake matrix from there, its just clean sand. This is in my opinion real matrix, I mean, who would spend so much time assembling fish verts, miniature bone fragments, micro teeth, and shell bits to create a good looking fake matrix for a horrible jaw ? The jaw might have been disarticulated, explaining the positioning of the teeth, wich are definetly not composite for the lack of plaster and carvings on the root, and then just badly preserved, maybe the pressure crushed it or some minor movement of the surroundings could have caused it. Also, the jaw biggest piece of bone there has one bigger groove for a nerv or blood vessel, and ends abruptly not in an unnatural way, its really the end of that bone. So could it be the back part of the dentary ?

[North]

27 minutes ago, Brevicollis said:

@pachy-pleuro-whatnot-odon So, you think that all of the matrix, the whole bonebed, with all sorts of different bone fragments like fish verts, mikro shark teeth, pieces of turtle carapace and shell bits is fake ? I have seen fake matrix from there, its just clean sand. This is in my opinion real matrix, I mean, who would spend so much time assembling fish verts, miniature bone fragments, micro teeth, and shell bits to create a good looking fake matrix for a horrible jaw ? The jaw might have been disarticulated, explaining the positioning of the teeth, wich are definetly not composite for the lack of plaster and carvings on the root, and then just badly preserved, maybe the pressure crushed it or some minor movement of the surroundings could have caused it. Also, the jaw biggest piece of bone there has one bigger groove for a nerv or blood vessel, and ends abruptly not in an unnatural way, its really the end of that bone. So could it be the back part of the dentary ?

Im sorry, but as mentioned earlier. Bone in your piece does not look like mosasaur bone, rather like in the other topic's bone texture.

[pachy-pleuro-whatnot-odon]

18 hours ago, Brevicollis said:

@pachy-pleuro-whatnot-odon So, you think that all of the matrix, the whole bonebed, with all sorts of different bone fragments like fish verts, mikro shark teeth, pieces of turtle carapace and shell bits is fake ? I have seen fake matrix from there, its just clean sand. This is in my opinion real matrix, I mean, who would spend so much time assembling fish verts, miniature bone fragments, micro teeth, and shell bits to create a good looking fake matrix for a horrible jaw ? The jaw might have been disarticulated, explaining the positioning of the teeth, wich are definetly not composite for the lack of plaster and carvings on the root, and then just badly preserved, maybe the pressure crushed it or some minor movement of the surroundings could have caused it. Also, the jaw biggest piece of bone there has one bigger groove for a nerv or blood vessel, and ends abruptly not in an unnatural way, its really the end of that bone. So could it be the back part of the dentary ?

 

It's confusing to have so many microfossils in the matrix, that's true. At the same time, maybe this vendor was experimenting with creating more realistic artificial matrix? Because it's not like these microfossils are rare, and they could probably have pulled them off of the shelf, just like that (or have mashed existing pieces of matrix together). They could also have simply used a block rich in microfossils as a base for their "artwork".

 

In any case, I'd say it's clear that this is a composite, because not only is the bone-texture off, it's also extremely rare to find a perfectly spaced preserved row of teeth, moreover of sizes and morphologies that don't consistently match jaw positions, and - from what I can tell - existing of at least two different species (the left-most two appear to be halisaurine teeth, whereas the rest are prognathodontine). And then there's this whole weird thing with so many roots showing. I'd say this is extremely rare as well, as normally the roots would've been ankylosed to the jaw, only to be exposed by natural replacement of the teeth or by the jaw bone being equally worn down to the same level across the length of the jaw-line - which seems very unlikely to naturally occur. Speaking of natural, since tooth replacement is an ongoing process in most reptile species - including mosasauroids - it's very unlikely for all the roots to stick out of the jaw at the same height - which would be even more so if they had fallen out of the jaw and washed away parallel to one another for distances that happened to align them perfectly in their final resting place.

 

No, there's jut too many things off about this piece for it to be authentic. I'm sorry...

[hadrosauridae]

Sorry, bu I agree with the others.  90+% of these "jaws" coming from morocco are composites and fakes.  If youre not extremely well versed in mosasaur species and morphologies, you should never buy things like this.  Assume everything is fake until you can prove it to be real.