Help with Fossil ID - Beltzville

[fossilisa]

I found these two fossils today and am hoping someone can help me positively identify.

[Caaaleb]

The first picture I think is most likely a fish spinal column or a Trilobite, but I'm not totally sure. The second picture I'm not sure.

Edited May 15, 2021 by Caaaleb

[PaleoOrdo]

I rather suggest a nautiloid, a longtitudal cross section, with visible siphuncle?

[Fossildude19]

Orthocone nautiloid for the first item, and spiriferid brachiopod internal mold for the second. 

[Tidgy's Dad]

I think the second one is the internal mold of a spiriferid brachiopod. 

[Rockwood]

First one is a partial mold of a trilobite. The camerae of the would be siphuncle don't line up right to match with those of the would be nautiloid in my opinion.

[Top Trilo]

The lines on the side don't look like a trilobite to me especially since they are not very symmetric

[Fossildude19]

39 minutes ago, Rockwood said:

First one is a partial mold of a trilobite. The camerae of the would be siphuncle don't line up right to match with those of the would be nautiloid in my opinion.

 

The first item is an inch long. Beltzville is a Devonian spot, and Eldredgeops rana is probably the most common trilobite found there. 

I don't see this as a thorax, but if it were, it would have had to have been a pretty big trilobite. An Eldredgeops of that size would be pretty rare, I think. 

The only larger trilobites there would possibly be Dipleura dekayi, which does not resemble this item.

This is why I went with cephalopod on this one.  

[Rockwood]

15 minutes ago, Fossildude19 said:

 

The first item is an inch long. Beltzville is a Devonian spot, and Eldredgeops rana is probably the most common trilobite found there. 

I don't see this as a thorax, but if it were, it would have had to have been a pretty big trilobite. An Eldredgeops of that size would be pretty rare, I think. 

The only larger trilobites there would possibly be Dipleura dekayi, which does not resemble this item.

This is why I went with cephalopod on this one.  

But the cross section is a dead ringer for a trilobite. And you know how I feel about 'what is supposed to be there' IDs. 

[Fossildude19]

2 minutes ago, Rockwood said:

But the cross section is a dead ringer for a trilobite. And you know how I feel about 'what is supposed to be there' IDs. 

We'll have to agree to disagree on the "dead ringer" thing.   

[westcoast]

+1 for orthocone siphuncle for first one

[EMP]

I have to go trilobite thorax on the first specimen and spiriferid brachiopod for the second. 

 

 

 

OP's specimen appears to have pleural furrows. Note also the rounded structures near the middle-left pleural lobe contact.

 

 

Compare this with an orthocone:

 

 

Note the lack of the rounded structures as exist near the contact of the middle-left pleural lobes in OP, and how the orthocone does not have furrows as OP's specimen does. 

 

As for the large size, I've seen fairly large phacopids from the Devonian of Virginia. It appears, if OP's specimen is a trilobite, most of the thorax is actually there, and so the specimen wouldn't have been much larger in life. Partial disarticulation post-death, camera angle, and other things can affect how large the specimen appears to be relative to the ruler. 

 

But that's my layman opinion, so take it with a grain of salt. 

[Top Trilo]

@Kane @piranha what do you see?

[Ludwigia]

Maybe a pic of the underside of that first one may help.

[PaleoOrdo]

On 5/16/2021 at 2:05 AM, Rockwood said:

The camerae of the would be siphuncle don't line up right to match with those of the would be nautiloid in my opinion.

If you look at the first picture (the other is unclear and gives a distorted view on the left side), the camarae is lined up perfectly with the segments of the siphuncle between the suture lines which I suggest is represented in the white "lines" on the left. 

[Rockwood]

12 minutes ago, PaleoOrdo said:

If you look at the first picture (the other is unclear and gives a distorted view on the left side), the camarae is lined up perfectly with the segments of the siphuncle between the suture lines which I suggest is represented in the white "lines" on the left. 

I believe the theory has a fatal flaw however. You can not dismiss the other views as evidence entirely.

Camera do not bifurcate to my knowledge. This would appear to exhibit such a condition.  

[PaleoOrdo]

5 minutes ago, Rockwood said:

I believe the theory has a fatal flaw however. You can not dismiss the other views as evidence entirely.

Camera do not bifurcate to my knowledge. This would appear to exhibit such a condition.  

I am discussing, not dismissing anything, the right side is puzzeling for me, but the left side have attributes which suites nautiloids. Suture lines, as far as I know, show a divide of the shell into chambers, not dividing each chamber. Am I wrong in that? Please correct me.

Edited May 18, 2021 by PaleoOrdo

[Fossildude19]

Dale, 

I'm slowly coming around to your way of thinking. 

I guess this is an EXTREMELY worn/eroded specimen. 

 

[Rockwood]

4 minutes ago, PaleoOrdo said:

I am discussing, not dismissing anything, the right side is puzzeling for me, but the left side have attributes which suites nautiloids. Suture lines, as far as I know, show a divide of the shell into chambers, not dividing each chamber. Am I wrong in that? Please correct me.

Notice in Tim's illustration that the area isn't where a suture between the septa and shell would be expected.

[PaleoOrdo]

6 minutes ago, Rockwood said:

Notice in Tim's illustration that the area isn't where a suture between the septa and shell would be expected.

Sorry, but I cannot see that. In which way? And how does it explain the right side? I still belive you should not use the second picture but the first. Moreover, actinocerid nautiloids (which are othoconic) are known to have flat ventral sides.

[Rockwood]

8 minutes ago, PaleoOrdo said:

Sorry, but I cannot see that. In which way? And how does it explain the right side? I still belive you should not use the second picture but the first. Moreover, actinocerid nautiloids (which are othoconic) are known to have flat ventral sides.

My bad. I missed the dimensional effect in the illustration. I see the post as a curved two (nearly) dimensional surface however. How it is seen as a cylinder sectioned is a mystery to me.

[PaleoOrdo]

5 minutes ago, Rockwood said:

How it is seen as a cylinder sectioned is a mystery to me.

If you mean the siphuncle: yes, it is not very clearly visible sectioned, but in actinocerids a siphuncle is composed of expanded segments that extend into the adjacent chambers, so this would made the sections not so clear. Also it could be cameral deposits near and around the siphuncle. A view of the underside might really help...

[Rockwood]

Mainers can be stubborn. 

[PaleoOrdo]

I checked if actinocerids nautiloids have cameral deposits. In general, according to Andy King and David Evans (High-level classification of the nautiloid cephalopods: a proposal for the revision of the Treatise Part K | Swiss Journal of Palaeontology | Full Text (springeropen.com) the occurrence of cameral deposits "appears to be restricted to members of the Orthoceratia", that is, the orders Astroviida, Endoceratida, Orthocerida and Pseudorthocerida. But Wikipedia writes that at least also in some actinocerids, namely Actinoceras, chambers are "short and contain cameral deposits which are more concentrated apically and ventrally". It is difficult say, if it is a nautiloid, about the overall concentration of deposits, since the OP seems to have broke off a part of the mature chambers, leaving intact the apical part. The sihuncle of actinocierids also often swells out in the chambers. The Cambridge university press website writes that cameral deposits are developed "commonly" in the order Actinoceratida.

I wonder also if the structures visible on the right side is something called viniculum or connecting tissue of calcite.

Edited May 18, 2021 by PaleoOrdo

[Rockwood]

3 hours ago, PaleoOrdo said:

I checked if actinocerids nautiloids have cameral deposits.

Yes. I guess there is a resemblance. If it means anything.  I somehow doubt they would fossilize the same way as the shell.