GuidesMagazineShopBuy FossilsJoin Hunts
RJC
Hello all,
Can anyone confirm my id of this fossil coral from the Carboniferous Limestone of North Wales as Diphyphyllum?  Each corallum is about 5mm in diameter. The photo background is square centimetres.

Many thanks IMG_20200204_161943.jpg  IMG_20200204_162114.jpg  IMG_20200212_143022 (2).jpg
Quote 0 0
prep01
Welcome to the forum. What a lovely colony. Hopefully Tarquin (TqB) will see it.
Colin Huller
Quote 1 0
TqB
Actually, it's hard to tell from Siphonodendron.

The critical thing is the mode of budding - in Diphyphyllum, it's parricidal which means the parent corallite discontinues, being replaced by two or more similarly sized smaller ones that then grow. So you see equal splitting. I'm not sure if that's what's happening here, it looks as if there may just be initially side branches which would mean Siphonodendron - it probably needs sections, or at least good closeups of the side view.

Also, I think I can see axial columns in some corallites which also means Siphonodendron. However, the single corallite in the last shot could be diphyphylloid (complete tabulae, no axial column) which does happen in Siphonodendron, often just in a few corallites. Or it may just be near the top of the calyx.
So it's not easy - to sum up, Siphonodendron can have diphyphylloid corallites, you need to see the budding to distinguish them!
 
Tarquin
Quote 1 0
RJC
Thanks Tarquin.  I have a lot to learn and your explanation is very useful.  I have attached a photo of a much bigger specimen collected from the same site which exhibits some branching.  Do you cut and polish to see detail or use acetate peels? IMG_20200212_200806.jpg 
Quote 0 0
CurtKnap
Hi RJC,

Do have a look at Tarquin's 'Carboniferous corals' thread in British Fossils  (https://www.discussfossils.com/post?id=8032312&pid=1297043892#post1297043892). This will show you as many cut and polished sections as you could ever wish to see and is also very informative.

Regards.
Quote 2 0
RJC
Oh yes, full of goodies! Thank you. 
Quote 1 0
TqB
RJC wrote:
Thanks Tarquin.  I have a lot to learn and your explanation is very useful.  I have attached a photo of a much bigger specimen collected from the same site which exhibits some branching.  Do you cut and polish to see detail or use acetate peels?  


Hi - I'm pretty sure that one is Siphonodendron, with clear lateral branches. Very nice specimen!
As you can see from the thread that Curt mentioned, I use polished sections. I have the materials for acetate peels but never bother! For photography, I nowadays just submerge the surface in water (by 1mm or so), and photograph with a DSLR camera (manual focus) on a copy stand with good lighting. 
Tarquin
Quote 0 0
RJC
Thanks again Tarquin. I will experiment on a few pieces. 
Quote 0 0
Write a reply...


Discussions on fossils, fossil hunting, rocks, locations, and identifying your finds.
(C)opyright 2019 - UKGE Ltd and UK Fossils - Contact us