Lance Formation Fossil ID

[Jurassicbro238]

I was able to dig in the Lance Formation last summer and finally got the chance to look at this find more closely. I don't think this is a dinosaur fossil and I'm not familiar with the skeletal anatomy of the other vertebrates at the site. Anyone know what it is? I tried taking all the relevant angles.

 

This one came from Niobrara County in Wyoming if that helps.

[Jurassicbro238]

Oh and I also wanted to mention that the scale bar is in cm

[Jurassicbro238]

Hello! Does anyone know what it is? Should I get better pictures? That massive indentation at one of the ends is seriously throwing me off.

[ThePhysicist]

@Troodon@jpc

[jpc]

That is a fun little bone.  I regret to say that I have no idea.  Your pictures are plenty good.  There are just so many little bones in the Lance.  While I may be able to ID many of them, many more remain a mystery.  Having said that, don't hesitate to post more fun finds.  I am almost thinking frog ilium, which has a big square end, but I don't think they have that hollow cupped surface on the other end. And it looks awful big for that.  

[Jurassicbro238]

15 minutes ago, jpc said:

That is a fun little bone.  I regret to say that I have no idea.  Your pictures are plenty good.  There are just so many little bones in the Lance.  While I may be able to ID many of them, many more remain a mystery.  Having said that, don't hesitate to post more fun finds.  I am almost thinking frog ilium, which has a big square end, but I don't think they have that hollow cupped surface on the other end. And it looks awful big for that.  

Oh well, at least I have a little bit more direction than I did before. Thanks jpc.

[Troodon]

Ditto no answers.  The first thing that crossed my mind when I saw it was Champsosaurus cervical rib but cupped end did not seem to fit.

[Jurassicbro238]

So I began comparing this bone with amphibian material since jpc begun leaning towards it being frog. I managed to stumble onto a paper about birds and found this reference. I'm starting to think it may be bird, especially when comparing it to A. What do you all think?

 

Thanks again @jpc and @Troodon for your time.

[jpc]

this looks pretty good.  What paper did you stumble upon? I would love to see the whole thing. 

[Troodon]

Checkout the images of this newly released paper in this topic

 

http://www.thefossilforum.com/index.php?/topic/128528-new-postcranial-specimens-of-ichthyornis-published/

[Jurassicbro238]

55 minutes ago, jpc said:

this looks pretty good.  What paper did you stumble upon? I would love to see the whole thing. 

I've attached the paper below. It's really fascinating.

 

25 minutes ago, Troodon said:

Checkout the images of this newly released paper in this topic

 

http://www.thefossilforum.com/index.php?/topic/128528-new-postcranial-specimens-of-ichthyornis-published/

Thanks Troodon! I didn't know that much Icthyornis material was reported on. I'll go through this paper carefully with my mystery bone. This paper will definitely be helpful in the future as well.

Western NA Maastrichtian Birds.pdf

[jpc]

Thanks for the paper link, Jurassicbro

 

[Jurassicbro238]

No problem jpc!

[DarasFossils]

Bird would be even cooler than Dinosaur if it is from the Cretaceous! Lucky find!

[Troodon]

12 hours ago, Jurassicbro238 said:

What do you all think?

 

Any way to determine if its thin walled and hollow?   That one end has matrix on it, can you exposed more of it.

[Troodon]

I showed the photos to a paleontologist, he did not have an answer but said we should consider an ilium of a mammal

[Jurassicbro238]

6 hours ago, Troodon said:

 

Any way to determine if its thin walled and hollow?   That one end has matrix on it, can you exposed more of it.

I'll spend some time removing more of it and give an update in a little bit.

 

Mammal ilium sounds pretty interesting too. Is mammal skeletal material known from HC/Lance? I was under the impression it was mostly teeth and jaws.

[Troodon]

At Tucson a few years ago Triebold displayed a skeleton of a Didelphodon don't recall how much was real.   Teeth and Jaws are what you see published but clueless to know how much isolated material is found and not identified.

 

[Jurassicbro238]

Makes sense. Hopefully in the future they find associated mammal skeleton from these sites. I can definitely seem some similarities in shape to my mystery bone.

 

Speaking of which, I managed to clean off the head(?) a bit more and it certainly looks hollow, though the matrix has filled up the larger holes and I'm not sure its safe to remove it. I did notice on the other end that there might be a hole on that little bump but the dirt won't come off so I just left it.

[jpc]

Thanks forthis photo, troodon.  I had no idea there is a Didelphodon skeleton out there in the world.  I do indeed wonder how much is real and how much is made ujp based on say, the modern opposum.  

[jpc]

just a gut feeling but I am leaning into the corcaoid camp.

[Troodon]

26 minutes ago, jpc said:

Thanks forthis photo, troodon.  I had no idea there is a Didelphodon skeleton out there in the world.  I do indeed wonder how much is real and how much is made ujp based on say, the modern opposum.  

Thats also my bet.  I'll ask them at Tucson

[Troodon]

37 minutes ago, jpc said:

just a gut feeling but I am leaning into the corcaoid camp.

 

Of what .....

[Jurassicbro238]

19 minutes ago, Troodon said:

 Its not hollow, I would not do any more for risk of damage

Darn, was starting to hope for an enantiornithine coracoid haha. Considering they look so similar to my mystery bone. I'll start looking for any references on small mammal hip elements if its possible.

Edited January 2, 2023 by Jurassicbro238

[Jurassicbro238]

Hmm, I think I'm leaning back towards the coracoid camp. I was able to find some references on ScienceDirect for small mammal/rodent hip morphology and while it looks similar, I noticed that it's not straight as my mystery fossil.

 

I also found this paper

Maga AM, Beck RMD. Skeleton of an unusual, cat-sized marsupial relative (Metatheria: Marsupialiformes) from the middle Eocene (Lutetian: 44-43 million years ago) of Turkey. PLoS One. 2017 Aug 16;12(8):e0181712. doi: 10.1371/journal.pone.0181712. Erratum in: PLoS One. 2017 Nov 9;12 (11):e0188132. PMID: 28813431; PMCID: PMC5559079.

 

They mentioned a lateral flaring of the ilium which was "unlike the condition in didelphids." Unsure what that means as the citation is locked behind a pay wall.

After comparing the bone to these citations and to the Maastrichtian bird and Ichthyornis papers, it seems that this bone most closely resembles enantiornithine A in Fig 1B from the Maastrichtian bird paper. Unfortunately one of the characteristics, a medial flange, is in the spot where the bone is missing so it's unclear. Although a bit of it may be preserved? I put it under the microscope and tried to take some pictures