Ordovician unknown...?

[mbarco]

Upper ordovician, Italy. Scale bar 5mm.
Decalcified specimen preserved as the internal and the external mould.

So the calcified occupied the space between the two moulds.

 

1) the only part of the external mould available. I think to see an ornamentation of narrow oblique parallel lines (red arrow).

 

2-3) two images of the internal mould.

 

4) an image of the external mould (overturned. Blue coloured) placed upon the internal mould.  I think almost in the same position it was before cracking the rock.

 

I had an idea, but the cross-shape at the bottom of the internal mould doesn't match anything in mind

Edited February 9, 2022 by mbarco

[piranha]

It looks like a possible genal or caudal spine of a trilobite. The intersecting 'cross' appears to have faint overlying lines that would suggest it is unrelated to the spine itself.

 

 

figures from:

 

Hammann, W., Leone, F. 2007

Trilobites from the Post-Sardic (Upper Ordovician) Sequence of Southern Sardinia. Part 2.

Beringeria: Würzburger Geowissenschaftliche Mitteilungen, 38:1-138

[mbarco]

Yes, but the cross shape of the interior mould? 

Do you talk about 2 perfectly overlyin' specimens?

Sorry, I don't understand

Edited February 10, 2022 by mbarco

[mbarco]

8 hours ago, piranha said:

It looks like a possible genal or caudal spine of a trilobite. The intersecting 'cross' appears to have faint overlying lines that would suggest it is unrelated to the spine itself.

 

 

figures from:

 

Hammann, W., Leone, F. 2007

Trilobites from the Post-Sardic (Upper Ordovician) Sequence of Southern Sardinia. Part 2.

Beringeria: Würzburger Geowissenschaftliche Mitteilungen, 38:1-138

Which "faint overlying lines" are you talking about?

[mbarco]

Looking the second picture I see a slight change of colour in the point I've marked with an arrow (picture #3)

[piranha]

13 hours ago, mbarco said:

Which "faint overlying lines" are you talking about?

 

Perhaps the 'overlapping' is only an optical illusion in this photo.

In that case, I have no other ID on this mysterious specimen.

[mbarco]

I understand your idea, but I'm not so sure it could be.