Is this a Spinosauridae partial spine or rib?

[-Andy-]

Hi all, I acquired a partial Spinosauridae caudal spine recently from the Kem Kem Beds. However, I was told that this is a dinosauria indet. rib.

 

The digger who provided me the fossil is experienced and trustworthy. Still, I would like to hear your thoughts on this fossil.

 

Thank you.

 

EDIT: Two others suggested that this is part of a scapula

 

[caldigger]

@Haravex look familiar?

[-Andy-]

@Troodon

@LordTrilobite

 

May I have your thoughts on this?

[LordTrilobite]

In the first photo it kinda does look like a neural spine of a Spinosaurid.

 

However, in the other photos we see that one side seems to be more rounded than the other. The edge also seems pretty sharp. The whole piece also has a slight bend to it. So if it's a spine it would have been leaning to the side.

 

Now, the slight bend itself is something that can happen in neural spines. I have a partial cervical neural arch of a Spinosaurid where the neural spine it bent to one side and it doesn't seem to be taphonomic. I don't have a lot of experience with the more distal parts of the neural spines in Spinosaurids as they are generally broke off at the base. But in my experience, at least at the base of the spine it should have a much more rounded edge.

 

It does actually look more like some type of rib of scapula. I don't think it's a neural spine.

I don't think it's the scapula of a Spinosaurid though. Here's one from my collection as reference. The bulge on you specimen doesn't quite match.

 

 

I'm actually also in the process of scanning a partial neural arch of a dorsal vertebra that has part of the base of the neural spine. When I'm done it might be good reference as well.

 

 

Photos of the broken surfaces would help with ID too btw.

[Troodon]

Not a lot of good comparative material around.  The neural spines I've seen including the dorsal in my collection are more flatish with rounded edges that don't come to a sharp edge.   It does seem to be more scapula like but like LordTrilobite said not that of a Spinosaurid given his specimen and the reconstructions Ive seen, photo below.  If not a Spino begs the question what animal.  Not sure it will change my mind but photos of the broken ends would be beneficial.

 

[-Andy-]

Thanks for the replies. Here's more pics of the cross section.

 

 

7 hours ago, LordTrilobite said:

In the first photo it kinda does look like a neural spine of a Spinosaurid.

 

However, in the other photos we see that one side seems to be more rounded than the other. The edge also seems pretty sharp. The whole piece also has a slight bend to it. So if it's a spine it would have been leaning to the side.

 

Now, the slight bend itself is something that can happen in neural spines. I have a partial cervical neural arch of a Spinosaurid where the neural spine it bent to one side and it doesn't seem to be taphonomic. I don't have a lot of experience with the more distal parts of the neural spines in Spinosaurids as they are generally broke off at the base. But in my experience, at least at the base of the spine it should have a much more rounded edge.

 

It does actually look more like some type of rib of scapula. I don't think it's a neural spine.

I don't think it's the scapula of a Spinosaurid though. Here's one from my collection as reference. The bulge on you specimen doesn't quite match.

 

 

I'm actually also in the process of scanning a partial neural arch of a dorsal vertebra that has part of the base of the neural spine. When I'm done it might be good reference as well.

 

 

Photos of the broken surfaces would help with ID too btw.

 

Yes, one side has a sharp edge, the other is rounded. There's indeed a slight bend to it.

 

Your scapula 3d scan is amazing and helpful. I have no idea what I have now. Hopefully these new pics will help.

 

3 hours ago, Troodon said:

Not a lot of good comparative material around.  The neural spines I've seen including the dorsal in my collection are more flatish with rounded edges that don't come to a sharp edge.   It does seem to be more scapula like but like LordTrilobite said not that of a Spinosaurid given his specimen and the reconstructions Ive seen, photo below.  If not a Spino begs the question what animal.  Not sure it will change my mind but photos of the broken ends would be beneficial.

 

 

Yeah, my seller has changed his mind about this ID too. He agrees it isn't neural spine. Here's more pictures.

[Troodon]

Cross-section of broken end has that Spino look, lots little pores.   Any chance its one of the hip bones like pubis 

 

Spino

 

 

[LordTrilobite]

I was thinking pubis or ischium as well.

 

Here's another slightly different angle of that same mount.

[-Andy-]

@hxmendoza is leaning towards scapula based on this. I think his analysis is valid

 

[LordTrilobite]

While the sharp edge fits, the bulge doesn't. Is that area at all broken? Because if it is and it was originally more straight then it might still fit. If that area is intact I still don't think it's a Spinosaur scapula since there shouldn't be such a bulge there on the underside of the scapula.

[Troodon]

The bulge is definitely an issue unfortunately  you cannot see the other side but you cannot rule it out.   Sadly we do not have good comparative bones to look at,  including all the others that might work.  Having said that the best one I see is LordTrilobites 3D specimen and that one does not seem to fit.   The scapula on this reconstruction, by the way,  was an isolated bone found in the KK so not associated with any skeleton.  It would be nice if you access all the bones on this reconstruction, I'm sure images were made.  Well what we can rule out are those bones in your orginal Q a spine or a rib. 

[-Andy-]

5 hours ago, LordTrilobite said:

While the sharp edge fits, the bulge doesn't. Is that area at all broken? Because if it is and it was originally more straight then it might still fit. If that area is intact I still don't think it's a Spinosaur scapula since there shouldn't be such a bulge there on the underside of the scapula.

 

It's not broken. There is a noticeable bulge there

 

59 minutes ago, Troodon said:

The bulge is definitely an issue unfortunately  you cannot see the other side but you cannot rule it out.   Sadly we do not have good comparative bones to look at,  including all the others that might work.  Having said that the best one I see is LordTrilobites 3D specimen and that one does not seem to fit.   The scapula on this reconstruction, by the way,  was an isolated bone found in the KK so not associated with any skeleton.  It would be nice if you access all the bones on this reconstruction, I'm sure images were made.  Well what we can rule out are those bones in your orginal Q a spine or a rib. 

 

Yeah any bit of info helps. For now, I will tentatively label it as a scapula/pubis/ischium. @hxmendoza also mentioned it could be a Carch

[Troodon]

I looked before to see if could find a Carch scapula from south america but no luck.    I think its Spino looking at the bone structure 

 

Edit:

Here is one

[LordTrilobite]

That looks like a bulge on that Carch scap.

 

Also for reference here's the scapula for Baryonyx.