North Sulfur River - Unknown Fossils Group #4

[Metafossical]

Newbie Notes          

                                                                                                                            

I’ve had these fossils for a while. I’ve had a chance to research them and I have an idea of what they might be  . . .  but as a newbie I’m not positive. So, I defer to the professionals for the final ID.

 

With the help of the veterans at this forum, (11) fossils were ID in my first two posts.

 

Thanks. 

 

The following pics are group number four.  The first fossil in this group was found a great distance away, but the depositional environment appears to be the same or similar. 

 

 

[JohnJ]

Do you have any additional views of the second fossil?  Do you think it is complete, or does there seem to be at least one broken surface?

 

The third fossil could be a very beat up mosasaur frontal.

[Metafossical]

22 hours ago, JohnJ said:

Do you have any additional views of the second fossil?  Do you think it is complete, or does there seem to be at least one broken surface?

 

The third fossil could be a very beat up mosasaur frontal.

 

Attached see additional views of the second fossil.  I believe it has one broken surface.  You are looking down at the broken surface in the first photo in situ.  Is this fossil posterior lower jaw, articular?  (Russell pg 51/52)

~

Is the first fossil in the series part of Xiphactinus?

~

Does the fourth fossil show Meckellan Canal as referenced by praefectus in North Sulfur River - Unknown Fossils Group #2?

 

 

[JohnJ]

6 hours ago, Metafossical said:

Attached see additional views of the second fossil.  I believe it has one broken surface.  You are looking down at the broken surface in the first photo in situ. 

 

I'm fairly sure this is part of a mosasaur quadrate.  

[JohnJ]

  I'll crawl out further on a limb and suggest it is the distal end of the suprastapedial process, possibly from a Clidastes sp..

 

@pachy-pleuro-whatnot-odon

[pachy-pleuro-whatnot-odon]

Not really sure where to begin on this... Difficult to make anything more than chunkosaur from this. But lets try anyway

 

On 7/5/2022 at 12:15 PM, Metafossical said:

Is the first fossil in the series part of Xiphactinus?

 

While I personally don't have any experience with Xiphactinus (or any significant knowledge on fish in general), the first fossil does strike me as a fish vertebra with spinous process still attached. The vertebra-nature of the specimen is best illustrated by the last photograph of it, as this most clearly preserves and shows the concavity that is that of a fish vertebra, and the spinous process attached to it. Xiphactinus could indeed be a good option.

 

On 7/4/2022 at 7:18 PM, JohnJ said:

The third fossil could be a very beat up mosasaur frontal.

 

Personally, I have a bit of difficulty identifying this specimen as a mosasaur frontal, as those would have a raised ridge rather than a depression, as seen in this specimen. Rather, I think that what we're seeing here is some kind of suture. Could be a palatal element - e.g., something like the vomer or palatine - but, to be honest, my anatomical knowledge falls a bit short in this area.

 

I'm pretty sure, though, that the final fossil is a bit of jaw bone, based on the internal texture, thinness, as well as the way it seems to consist of superimposed bits of bone.

 

On 7/5/2022 at 6:37 PM, JohnJ said:

I'm fairly sure this is part of a mosasaur quadrate.

 

On 7/7/2022 at 11:55 PM, JohnJ said:

I'll crawl out further on a limb and suggest it is the distal end of the suprastapedial process, possibly from a Clidastes sp..

 

While Clidastes sp. is a very reasonable guess for material found on the NSR, I don't have enough experience with mosasaur quadrates yet to confirm or deny this identification. However, looking over some photographs of this particular specimen (specific photographs cited below), I do think John is right in that the specific curvature and roughened texture are very much like the tympanic ala of a mosasaur quadrate. However, I don't think it's from the suprastapedial process, since the bone doesn't show the narrowing/tapering you'd normally expect to see there, and wouldn't be able to tell the species. For comparison, take a look here.

 

 

On 7/4/2022 at 3:28 PM, Metafossical said:

 

On 7/5/2022 at 12:15 PM, Metafossical said:

 

[JohnJ]

On 7/8/2022 at 7:51 PM, pachy-pleuro-whatnot-odon said:

 

While Clidastes sp. is a very reasonable guess for material found on the NSR, I don't have enough experience with mosasaur quadrates yet to confirm or deny this identification. However, looking over some photographs of this particular specimen (specific photographs cited below), I do think John is right in that the specific curvature and roughened texture are very much like the tympanic ala of a mosasaur quadrate. However, I don't think it's from the suprastapedial process, since the bone doesn't show the narrowing/tapering you'd normally expect to see there, and wouldn't be able to tell the species. For comparison, take a look here.

 

If I am envisioning @Metafossical's find properly, my reasoning is based on the features, texture and shape of some mosasaur quadrates.  From a recent paper, Palci, Konishi, Caldwell 2021

A COMPREHENSIVE REVIEW OF THE MORPHOLOGICAL DIVERSITY OF THE QUADRATE BONE IN MOSASAUROIDS (SQUAMATA: MOSASAUROIDEA), WITH COMMENTS ON THE HOMOLOGY OF THE INFRASTAPEDIAL PROCESS

 

Quote

In Clidastes there is a prominence posteromedially and in alignment with the quadrate shaft, the posteromedial process, and a distinct depression on the dorsal surface of the distal end of the suprastapedial process. 

 

 

Their image shows the right quadrate in lateral, medial, and posterior views. There seems to be very slight damage to the lateral edge on the end of the suprastapedial process.

 

@Metafossical's find shows similarity to the left quadrate suprastapedial process of a Clidastes sp.  I see the orientation as follows:

 

 

 

Bear in mind that twists and bends in the bone influence perimeter outlines in these images.

[pachy-pleuro-whatnot-odon]

19 minutes ago, JohnJ said:

If I am envisioning @Metafossical's find properly, my reasoning is based on the features, texture and shape of some mosasaur quadrates.  From a recent paper, Palci, Konishi, Caldwell 2021

A COMPREHENSIVE REVIEW OF THE MORPHOLOGICAL DIVERSITY OF THE QUADRATE BONE IN MOSASAUROIDS (SQUAMATA: MOSASAUROIDEA), WITH COMMENTS ON THE HOMOLOGY OF THE INFRASTAPEDIAL PROCESS

 

Sounds like a very interesting publication! Too bad it's paywalled, though In any case, for others trying to find it, here's the link.

 

But, yeah, I see what you mean with the depression. I don't think I've seen this in other mosasaurs, so quite interesting to see. And, if this is indeed unique to Clidastes spp., I'd most certainly agree that this is what OP has here. Pretty cool piece!

[Metafossical]

On 7/8/2022 at 7:51 PM, pachy-pleuro-whatnot-odon said:

Not really sure where to begin on this... Difficult to make anything more than chunkosaur from this. But lets try anyway

 

 

While I personally don't have any experience with Xiphactinus (or any significant knowledge on fish in general), the first fossil does strike me as a fish vertebra with spinous process still attached. The vertebra-nature of the specimen is best illustrated by the last photograph of it, as this most clearly preserves and shows the concavity that is that of a fish vertebra, and the spinous process attached to it. Xiphactinus could indeed be a good option.

 

 

Personally, I have a bit of difficulty identifying this specimen as a mosasaur frontal, as those would have a raised ridge rather than a depression, as seen in this specimen. Rather, I think that what we're seeing here is some kind of suture. Could be a palatal element - e.g., something like the vomer or palatine - but, to be honest, my anatomical knowledge falls a bit short in this area.

 

I'm pretty sure, though, that the final fossil is a bit of jaw bone, based on the internal texture, thinness, as well as the way it seems to consist of superimposed bits of bone.

 

 

 

While Clidastes sp. is a very reasonable guess for material found on the NSR, I don't have enough experience with mosasaur quadrates yet to confirm or deny this identification. However, looking over some photographs of this particular specimen (specific photographs cited below), I do think John is right in that the specific curvature and roughened texture are very much like the tympanic ala of a mosasaur quadrate. However, I don't think it's from the suprastapedial process, since the bone doesn't show the narrowing/tapering you'd normally expect to see there, and wouldn't be able to tell the species. For comparison, take a look here.

 

 

 

 

 

On 7/10/2022 at 2:16 PM, JohnJ said:

 

If I am envisioning @Metafossical's find properly, my reasoning is based on the features, texture and shape of some mosasaur quadrates.  From a recent paper, Palci, Konishi, Caldwell 2021

A COMPREHENSIVE REVIEW OF THE MORPHOLOGICAL DIVERSITY OF THE QUADRATE BONE IN MOSASAUROIDS (SQUAMATA: MOSASAUROIDEA), WITH COMMENTS ON THE HOMOLOGY OF THE INFRASTAPEDIAL PROCESS

 

 

 

Their image shows the right quadrate in lateral, medial, and posterior views. There seems to be very slight damage to the lateral edge on the end of the suprastapedial process.

 

@Metafossical's find shows similarity to the left quadrate suprastapedial process of a Clidastes sp.  I see the orientation as follows:

 

 

 

Bear in mind that twists and bends in the bone influence perimeter outlines in these images.choose files...

 

 

Thank you all for your replies.

 

 

 

Sorry I haven’t replied sooner.

 

I’ve been reading some interesting papers, reviewing historical maps, comparing and reviewing mosasaur anatomical diagrams and pics, taking photos of fossils to post and preparing for the next fossil hunt.   In short, fossils on the brain.

 

Looking forward to the next fossil hunt  . . .  

~

With respect to quadrate fossil, please see attached pics.

 

I believe the pictures show said fossil is the “broken off” top of the quadrate where it articulates w/skull.  The arrow points at articulation w/cervical vertebrae.

Considering the size of the fossil and earlier comments by JohnJ, this appears to be a “large animal.”