Dicranurus spine?

[TNDevonian]

This is from the Devonian Birdsong shale in Parsons, TN USA. It is a solid spine resting across a Dalmanites retusus tail molt. I can’t think of anything with this slender taper and length other than a rare-for-Tennessee, Dicranurus spine. Is this a correct assumption?

[Lone Hunter]

Just refreshing this, also curious.

[Top Trilo]

I find it odd that its a different color than the trilobite its resting upon. If they are both trilobite parts I'd expect them to be the same or similar. As to what else it may be, I don't know.

[Mark Kmiecik]

4 hours ago, Top Trilo said:

I find it odd that its a different color than the trilobite its resting upon. If they are both trilobite parts I'd expect them to be the same or similar. As to what else it may be, I don't know.

It may be part of a different trilobite.

[Top Trilo]

3 hours ago, Mark Kmiecik said:

It may be part of a different trilobite.

Yes, the OP said it was a Dalmanites retusus pygidium, but I believe they both should be composed of the same mineral and since their preserved in the same place I'd expect the same color.

[TNDevonian]

23 hours ago, Top Trilo said:

Yes, the OP said it was a Dalmanites retusus pygidium, but I believe they both should be composed of the same mineral and since their preserved in the same place I'd expect the same color.

This formation sports brown and black trilobites together quite often, and I have a set of tan Dicranurus "horns" next to a black D, retusus pygidium, next to a tan Phacops longi, next to a brown unidentified pygidium, so color is not definitive here. The Dicranurus sp. here tend to be quite small from my experience, and it is the length, and smooth extended taper that leads me to believe it is from one of them. 

[Top Trilo]

29 minutes ago, TNDevonian said:

This formation sports brown and black trilobites together quite often, and I have a set of tan Dicranurus "horns" next to a black D, retusus pygidium, next to a tan Phacops longi, next to a brown unidentified pygidium, so color is not definitive here. The Dicranurus sp. here tend to be quite small from my experience, and it is the length, and smooth extended taper that leads me to believe it is from one of them. 

Thank you for explaining this to me, that sounds like a really cool plate! I can't think of anything else it may be, is Dicranurus the only trilobite with spines that fit this size in the formation? I'll tag one of our resident trilobite experts, @piranha

[piranha]

Similar coloration to Dicranurus hamatus elegantus from the Haragan Fm of Oklahoma.

 

[Mark Kmiecik]

On 11/29/2022 at 5:00 PM, Top Trilo said:

Yes, the OP said it was a Dalmanites retusus pygidium, but I believe they both should be composed of the same mineral and since their preserved in the same place I'd expect the same color.

 

Looked at the post again. Missed that the first time around. Thanks for the heads up.

 

[TNDevonian]

17 hours ago, Top Trilo said:

Thank you for explaining this to me, that sounds like a really cool plate! I can't think of anything else it may be, is Dicranurus the only trilobite with spines that fit this size in the formation? I'll tag one of our resident trilobite experts, @piranha

 

Yes, the Dicranurus is the only one that I know of that has spines that would have such a thin taper over that much distance. The pygidial and genal spines of the more common species would have quickly increased width over that much length.

 

Edited December 1, 2022 by TNDevonian
Complete answer to missed part of question.