Unknown Cretaceous limb bone from eastern North Carolina

[fossil_lover_2277]

I just recently found this bone in the Cretaceous Black Creek group deposits of eastern North Carolina. I think it is either crocodile or turtle. I am almost positive it isn’t mosasaur, dinosaur, or plesiosaur (some other tetrapods found in the Black Creek group). Also, is it a radius, ulna, tibia, fibula, femur, etc.? Or is it even a limb bone? I have no idea. Thanks!

Edited November 19, 2021 by fossil_lover_2277

[val horn]

I have no idea what you have.  I doubt it is turtle because of the deep central grove.  It is very solid looking , what does the broken end look like.  Also if you look into the pinned topics coco has a printable  cm paper.  You should print some, please.

[val horn]

@Troodon , @pachy-pleuro-whatnot-odon

[JohnJ]

It reminds me of a mosasaur ilium.

 

[fossil_lover_2277]

12 hours ago, val horn said:

I have no idea what you have.  I doubt it is turtle because of the deep central grove.  It is very solid looking , what does the broken end look like.  Also if you look into the pinned topics coco has a printable  cm paper.  You should print some, please.

It’s definitely fossil bone, but it’s heavily mineralized, you can see the cancellous bone inside both ends. Here’s several pics I took of the broken end:

 

 

Edited November 20, 2021 by fossil_lover_2277

[val horn]

I agree thst it looks like bone,  i wanted to see if it looked hollow like s bird bone or if it looked crushed.  Unfortunately the pictures dont really help me but maybe someone more knowledgeable will see something. 

 

 

[fossil_lover_2277]

11 hours ago, JohnJ said:

It reminds me of a mosasaur ilium.

 

I looked at some images of mosasaur ilium online, it looks spot on. That would explain why it’s so flattened and it narrows towards the end

[fossil_lover_2277]

Here are some examples specifically of a tylosaur, which would be reasonable for the stratum it’s from:

 

 

[Coco]

20 hours ago, val horn said:

I have no idea what you have.  I doubt it is turtle because of the deep central grove.  It is very solid looking , what does the broken end look like.  Also if you look into the pinned topics coco has a printable  cm paper.  You should print some, please.

Have a look on my signature

 

Coco

[pachy-pleuro-whatnot-odon]

On 11/19/2021 at 7:55 PM, fossil_lover_2277 said:

I think it is either crocodile or turtle.

 

Unfortunately, my knowledge of turtles is really minimal, so can't really make an argument for or against that. What I can say, however, is that, in my opinion at least, this doesn't look like a limb bone of either, since 1) those are generally much curvier and less flat; and 2) they wouldn't have a groove starting past the articulation surface like your specimen does: if a depression is present, this normally connects to the articulation surface. Ruling out skull bones and vertebrae, this, for turtles, I believe, mainly leaves peural bones as a potential match. However, this also doesn't seem to make too much sense, as those kind of bones look kind of like a rib with a backing plate, much as these examples from @Al Dente's collection below (see this thread for more information on turtle pleurals):

 

 

 

On 11/20/2021 at 12:46 PM, val horn said:

It is very solid looking , what does the broken end look like.

 

13 hours ago, fossil_lover_2277 said:

It’s definitely fossil bone, but it’s heavily mineralized, you can see the cancellous bone inside both ends.

 

7 hours ago, val horn said:

I agree thst it looks like bone,  i wanted to see if it looked hollow like s bird bone or if it looked crushed.

 

I think there's a good reason to have taken a look at the internal structure of the bone, as this allows us to confirm the dense nature of the bone, thereby that it almost assuredly belonged to a marine creature, by extension, considering the geological context, a marine reptile.

 

As to what the bone could be or belong to I find very difficult. Of course there is a certain semblance to rib, and ribs may have a central depression running their length (as is the case in ichthyosaurs, plesiosaurs and mosasaurs, to name a few), but such a depression, when present, is often found on both sides of the rib. Moreover, this particular specimen lacks the curvature you'd normally associate with rib and, additionally, tapers very rapidly and out of sync with the depression. I therefore doubt this being a rib fragment either.

 

19 hours ago, JohnJ said:

It reminds me of a mosasaur ilium.

 

I can get behind this hypothesis, though, knowing @JohnJ's experience with mosasaurs. Unfortunately, mosasaur material is quite rare here in Europe, even in museums, and I have therefore had little opportunity to familiarise myself with these mosasaur skeletal parts: they were almost always missing in the museum specimens I've seen, and I have yet to be able to acquire some mosasaur pelvic bones for my collection... However, I did find these photographs from the Naturmuseum Senckenberg in Frankfurt which seem to perfectly illustrate the bone you've found. And from all suggestions we've heard and gone through, I think it is the best one by far.

 

 

Tylosaurus proriger from Tweed Gore in Kansas

 

 

However, just for completeness, let me tag @Carl and @caterpillar. May be they've still got something to add...

Edited November 21, 2021 by pachy-pleuro-whatnot-odon

[fossil_lover_2277]

Thank you so much for your time @pachy-pleuro-whatnot-odon in figuring this one out, I really appreciate the help!!! So cool to know it’s the hip bone of a mosasaur 

Edited November 22, 2021 by fossil_lover_2277

[pachy-pleuro-whatnot-odon]

7 hours ago, fossil_lover_2277 said:

Thank you so much for your time @pachy-pleuro-whatnot-odon in figuring this one out, I really appreciate the help!!! So cool to know it’s the hip bone of a mosasaur 

 

Thanks for the praise! 

It was @JohnJ's suggestion that got me on to it, though

[Carl]

On 11/21/2021 at 8:32 AM, pachy-pleuro-whatnot-odon said:

 

Unfortunately, my knowledge of turtles is really minimal, so can't really make an argument for or against that. What I can say, however, is that, in my opinion at least, this doesn't look like a limb bone of either, since 1) those are generally much curvier and less flat; and 2) they wouldn't have a groove starting past the articulation surface like your specimen does: if a depression is present, this normally connects to the articulation surface. Ruling out skull bones and vertebrae, this, for turtles, I believe, mainly leaves peural bones as a potential match. However, this also doesn't seem to make too much sense, as those kind of bones look kind of like a rib with a backing plate, much as these examples from @Al Dente's collection below (see this thread for more information on turtle pleurals):

 

 

 

 

 

 

I think there's a good reason to have taken a look at the internal structure of the bone, as this allows us to confirm the dense nature of the bone, thereby that it almost assuredly belonged to a marine creature, by extension, considering the geological context, a marine reptile.

 

As to what the bone could be or belong to I find very difficult. Of course there is a certain semblance to rib, and ribs may have a central depression running their length (as is the case in ichthyosaurs, plesiosaurs and mosasaurs, to name a few), but such a depression, when present, is often found on both sides of the rib. Moreover, this particular specimen lacks the curvature you'd normally associate with rib and, additionally, tapers very rapidly and out of sync with the depression. I therefore doubt this being a rib fragment either.

 

 

I can get behind this hypothesis, though, knowing @JohnJ's experience with mosasaurs. Unfortunately, mosasaur material is quite rare here in Europe, even in museums, and I have therefore had little opportunity to familiarise myself with these mosasaur skeletal parts: they were almost always missing in the museum specimens I've seen, and I have yet to be able to acquire some mosasaur pelvic bones for my collection... However, I did find these photographs from the Naturmuseum Senckenberg in Frankfurt which seem to perfectly illustrate the bone you've found. And from all suggestions we've heard and gone through, I think it is the best one by far.

 

 

Tylosaurus proriger from Tweed Gore in Kansas

 

 

However, just for completeness, let me tag @Carl and @caterpillar. May be they've still got something to add...

I can't really add much here, but I agree that of what has been proposed, the mosasaur ilium looks like the strongest bet.