One mosasaur? SD

[Slow Walker]

Could these all be from 1 animal?  Found these scattered about in Pierre shale but all within 50ft. Wonder if I should try to find the origin of where they are coming from. The paddle bone looked small compare to the verts. Would this be an adult? ID on parts would be helpful to. Thanks

[jpc]

yeah, that arm bone looks too small.  Looks like you found some well preserved material out there.... Woo hooo!!!

[Praefectus]

Nice find. I am not sure there is any reason to think these are from the same skeleton, though. 

[pachy-pleuro-whatnot-odon]

Seems to be at least a couple of caudal vertebrae in there. The paddle bone could come from a rear paddle, explaining why it might be smaller. Still, it's difficult to identify mosasaur vertebrae to species and, as such, hard to say if they'd be from the same individual. Never hurts to look for the origin of the vertebrae, though

 

All the same, great finds!

Edited January 29, 2023 by pachy-pleuro-whatnot-odon

[Slow Walker]

1 hour ago, Praefectus said:

Nice find. I am not sure there is any reason to think these are from the same skeleton, though. 

Well there location was close together. but size seemed different to me. 

[Slow Walker]

1 hour ago, pachy-pleuro-whatnot-odon said:

Seems to be at least a couple of caudal vertebrae in there. The paddle bone could come from a rear paddle, explaining why it might be smaller. Still, it's difficult to identify mosasaur vertebrae to species and, as such, hard to say if they'd be from the same individual. Never hurts to look for the origin of the vertebrae, though

 

All the same, great finds!

Thanks!

I meant name of bone types. One looked to flat for vert.

Not spieces. 

[pachy-pleuro-whatnot-odon]

9 minutes ago, Slow Walker said:

Thanks!

I meant name of bone types. One looked to flat for vert.

Not spieces. 

 

All of them, except one, are vertebrae. The rounded ones with the two "nubbins" close together on the hollow end of the vertebra are terminal caudal vertebrae, those with the "wings" to their sides are lumbar or pygal ones (can't make all of them out with sufficient detail). The flat paddle bone is probably a tibia (these bones can have slightly different morphologies depending on genus and species, which I'm unfortunately not familiar with, hence the presumption).

 

(source)

 

Rear paddle of Prognathodon overtoni (Konishi, Brinkman, Massare and Caldwell, 2011)

[Slow Walker]

On 1/29/2023 at 5:04 PM, pachy-pleuro-whatnot-odon said:

 

All of them, except one, are vertebrae. The rounded ones with the two "nubbins" close together on the hollow end of the vertebra are terminal caudal vertebrae, those with the "wings" to their sides are lumbar or pygal ones (can't make all of them out with sufficient detail). The flat paddle bone is probably a tibia (these bones can have slightly different morphologies depending on genus and species, which I'm unfortunately not familiar with, hence the presumption).

 

(source)

 

Rear paddle of Prognathodon overtoni (Konishi, Brinkman, Massare and Caldwell, 2011)

Do you know if the 2 limbs shown are both rear limbs? The either tibia look a bit different from each other. Thanks

[JohnJ]

41 minutes ago, Slow Walker said:

Do you know if the 2 limbs shown are both rear limbs? The either tibia look a bit different from each other. Thanks

 

Note that both have "fe" = femur, "ti" = tibia, and "fi" = fibula.

[pachy-pleuro-whatnot-odon]

4 hours ago, Slow Walker said:

Do you know if the 2 limbs shown are both rear limbs? The either tibia look a bit different from each other. Thanks

 

3 hours ago, JohnJ said:

Note that both have "fe" = femur, "ti" = tibia, and "fi" = fibula.

 

I agree both do superficially look a bit different. But if you look at the morphology of the bones more closely, you note that they do actually look quite similar. Thus, they're just differentially preserved paddles from opposite sides of the body, as can also be seen from the skeletal overview photograph.

[Slow Walker]

8 hours ago, JohnJ said:

 

Note that both have "fe" = femur, "ti" = tibia, and "fi" = fibula.

 

5 hours ago, pachy-pleuro-whatnot-odon said:

 

 

I agree both do superficially look a bit different. But if you look at the morphology of the bones more closely, you note that they do actually look quite similar. Thus, they're just differentially preserved paddles from opposite sides of the body, as can also be seen from the skeletal overview photograph.

I understand they are labeled the same but there are a few noticeable shape differences. Could that be from pieces missing or disfiguring of it during preservation? 

Also do you know why photos often in research papers are black and white?

[Kane]

Just now, Slow Walker said:

 

Also do you know why photos often in research papers are black and white?

Colour can be distracting. Generally, black and white photos will better show the contrast of the diagnostic features. It can also be common with some fossils to add ammonium chloride vapour to accentuate those diagnostic features, so showing colour would be moot in such a circumstance.

[pachy-pleuro-whatnot-odon]

43 minutes ago, Slow Walker said:

I understand they are labeled the same but there are a few noticeable shape differences. Could that be from pieces missing or disfiguring of it during preservation?

 

Well, apart from the fact that both paddles would be mirror image from one another, and the second paddle being incomplete, I think it's perfectly possible that there could be some plastic deformation, as well as differential taphonomic effects that would change the appearance of either paddle. Overall, though, I'd say these differences are but minor variations when you compare them to interspecific or intergeneric variability. That is, I don't see the differences here as being overly big...