Cretaceous sponges?

[FranzBernhard]

Hello,

 

again I would like to ask for your kind help. I have two sectioned fossils from the Campanian Gosau basin of Kainach, Styria, Austria (St. Bartholomä-Formation). They are accompanied by radiolitid rudists (R), but I don´t think that they are rudists by itself. Could these be some kind of sponges? But I can not see any spicules. Frist specimen is 13.5 cm high, sections are ca. 3 mm apart. Second specimen is 11.5 cm wide, sections are ca. 16 mm apart. There is nothing visible on the wheatered surface, except some Radiolitid fragments.

 

I know this website:

http://www.cretaceous.de/

But I have not found anything definitive about sponges of the Austrian Gosau formations. Maybe someone can give me a hint?

 

Thank you very much for your help!
Franz Bernhard

 

Specimen 1

Specimen 2

[Arizona Chris]

It does look pretty spongey.  Usually, you cant see spicules in fossil sponges, they are too small to fossilize well or are mixed in with the silica entombing the sponge.  Maybe a Leucon Hexactanellid?

[abyssunder]

They look to be rudists, to me, but it will be difficult to make an assignment to a genus or species.

If I compare the picture of your specimen with the one from here, I can see similar patterns suggesting rudist, not sponge.

 

 

 

[FranzBernhard]

Thank you for your comments, Arizona Chris and abyssunder!

So it is even difficult to assign a phylum...

 

I forgot do mention, that the lowermost, small radiolitid is clearly growing on the fossil in question.

 

Thanks again,

Franz Bernhard