Please help ID these two fossils

[PaleoOrdo]

I wonder what the line in this rock could be, to the right of the brachiopod. The line is less than 1 mm in diameter. Also if it is possible ID the genus or family of the braciopod? The age is Mid or Late Ordovician.

[kgbudge]

My first thought is stem bryozoan.

 

My second is a vein of calcite in the rock.

 

Gotta warn  you, though, that I'm the guy who mistook flow-banded rhyolite for an algal mound once.

[PaleoOrdo]

Thank you for your reply and suggestions. About the line; I also was thinking for a while it might be a bryozoan, because of the small size and bryozoa have tube-structures. Bryozoa should have a more complex structure, but it could, as you suggest, be a stem part. A vein of calcite I not think it is, because having looked at many rocks in the area, I didn't see such intrusions. The line could be part of a bigger animal, but I think it may be impossible to know.

By the way, thanks for the link to your nice website.

Edited January 24, 2022 by PaleoOrdo

[PaleoOrdo]

 

Could the brachiopod be an orthid, a specimen of the genus Glyptorthis or Plectorthis? This genus has moderately sized, biconvex shell with clear radial ornament, and shell shape ranges from subquadrate to subelliptical. The genus' age is from uppermost Darriwilian to mid Katian in Laurentia. The finds in Baltica is much less in numbers. Occurrences of Plectorthis in Baltica, according to Sproat and Jin (2016), are represented by "a few moulds of Plectorthis sp. from the Kalstad Limestone of Norway and from the Norderhov Formation and the Kirkerud Group. None of these unnamed species are particularly abundant, and the first two are known only from moulds and casts. If these species can be confirmed to be true Plectorthis, their occurrences would be in cool-water subtropical environment similar to the Cincinnatian Arch area in Laurentia." So the age is within my estimate of the OP-formation.

Edited January 24, 2022 by PaleoOrdo

[Bobby Rico]

Maybe our mate @Tidgy's Dad can help 

[PaleoOrdo]

I think this may be the same species, found at the same location, and same size:

To other bachiopods from the same location:

[Tidgy's Dad]

Yes, they're orthids, but not Plectorthis nor Glyptorthis. 

Do you have a more precise location, please? 

Edited January 28, 2022 by Tidgy's Dad

[PaleoOrdo]

5 hours ago, Tidgy's Dad said:

Do you have a more precise location, please?

The location is Tyrifjorden in the Oslo-field, Holsfjorden at the western side. I checked the geological map again and it is somehow difficult to see exactly just from the map, as it is many faults there, with many formations just within a few kilometer. I believe it is Late Ordovician, but it may be very earliest silur. I need to go back to the location to check more with the map to be sure where the border between these two formations is. A paleontologist I spoke with last year said that if the rock in the whole area there is sandstone, then it is Silurian (but I know that is a simplification and not absolutely true). My rocks are limestone ...

Edited January 28, 2022 by PaleoOrdo