Anyone know what it is? Northern Lithuanian boulder find

[D.N.FossilmanLithuania]

Good evening everyone,

 

Today I found this fossil similar to trilobite cranidium but it has very primitive features. 

I noticed some similar imprints earlier in similar kinds of erratic boulders but they were poorly preserved- I also can say that one dolomite limestone with similar partial imprint had orthogastropod like remains. I am not sure if this taxon is from Ordovician or is it even Cambrian in age, what would be more possible talking about primitive arthropods including trilobite ancestors. 

Please help me to know what it is, then I could know the precise age of this type of erratic boulders.

The fossil is taken as two halves with internal and external armor imprint, it is about 1 cm length.

 

Best Regards

Domas  

[fifbrindacier]

Hi, i really don't know if it is a trilobite. If this layer is Cambrian, and, a fortiori if it is Ordovician, this isn't a trilobite ancestor because trilobites existed yet in the early Cambrian.

Your photos are too "bad" for me, they seem "shiny" and "silver plated" i can't see more precise features. Could you, please, just take pics without too much improvement ?

[D.N.FossilmanLithuania]

1 hour ago, fifbrindacier said:

Hi, i really don't know if it is a trilobite. If this layer is Cambrian, and, a fortiori if it is Ordovician, this isn't a trilobite ancestor because trilobites existed yet in the early Cambrian.

Your photos are too "bad" for me, they seem "shiny" and "silver plated" i can't see more precise features. Could you, please, just take pics without too much improvement ?

Dear fifbrindacer,

I recently took the pictures by simple camera, maybe they could help. 

 

[Ludwigia]

Maybe @piranha can help you.

[westcoast]

This is reminding me of inarticulate brachiopod but I can't find a good match

[D.N.FossilmanLithuania]

I recently noticed that my specimen is very similar to early aglaspidid.

Here is the link in Glypharthrus (Family Aglaspididae): https://www.researchgate.net/figure/Glypharthrus-magnoculus-sp-nov-from-the-Jiangshanian-Furongian-part-of-the-McKay_fig3_309549546

And another link in the all history of aglaspidids and other primitive arachnomorphs: https://www.nature.com/articles/s41598-017-11610-5?WT.feed_name=subjects_evolution

 

@piranha I think the specimen is the most typical to aglaspidid arthropod cephalon, and it is more similar to Late Cambrian Aglaspididae than Ordovician Tremaglaspididae because the eyes of aglaspididae are inclined in bottom as in my specimen.  What would you think, I am correct?

 

Best Regards

Domas  

[piranha]

 I don't see any arthropod features.  I agree with @westcoast they are brachiopods.  A colleague commented:

 

"The bilobed structure looks like a brachial valve cardinal process.  The round one may be an adductor scar."

[D.N.FossilmanLithuania]

19 hours ago, piranha said:

 I don't see any arthropod features.  I agree with @westcoast they are brachiopods.  A colleague commented:

 

"The bilobed structure looks like a brachial valve cardinal process.  The round one may be an adductor scar."

Ok maybe it is brachiopod fossil, but could you show literature in brachiopod families with the most similar appearance of valves (the cardinal process and adductor scar that you mentioned)? I just need to compare my fossil find with the most similar brachiopod remains to know the exact age of these erratic boulders.

Thank you.

 

[piranha]

There is a mountain of brachiopod literature.. .. sounds like a fun research project.  Hopefully one of our brachiopod specialists can assist further.

 

[fifbrindacier]

You also can show your specimen on that site : http://www.braquiopodos.es, but, as Piranha said, it's a mountain because brachiopods existed yet in the Kimmerigdian and still exist now.

 

Maybe could you also narrow the epoqua down by looking a geologic map of the place you found them. Or, if those erratic boulders were brang by humans activities, ask questions about from where they come and have a look on the geologic map of that area.

[D.N.FossilmanLithuania]

10 hours ago, fifbrindacier said:

You also can show your specimen on that site : http://www.braquiopodos.es, but, as Piranha said, it's a mountain because brachiopods existed yet in the Kimmerigdian and still exist now.

 

Maybe could you also narrow the epoqua down by looking a geologic map of the place you found them. Or, if those erratic boulders were brang by humans activities, ask questions about from where they come and have a look on the geologic map of that area.

Thank you very much, I am going to show this brachiopod in the site you mentioned