Rudist

[drbush]

Dear friends can you help me with this?

It is a horn like fossil , 7cm by 4 cm  , in matrix , the matrix is oyster texture .

It was a surface find under Aruma mountain , 80 km to the North of Riyadh city, the capital of Saudi Arabia.

The area is Cretaceous, Aruma Formation.

[Rockwood]

I've never seen a rudist, but it's what I would guess. 

[Tidgy's Dad]

+ 1 for possible rudist. 

Nice find. 

[daves64]

I like the matrix on it, especially the banded, wavey, rippled part. 

[Manticocerasman]

indeed likely a rudist.

 

@FranzBernhard can you confirm?

 

 

[FranzBernhard]

From the pics, I would also have said rudist, too, mostly a steinkern. But I am not completely sure. The matrix is really strange, maybe its mostly the shell of the rudist?

I think, I can see the contact beween the upper and lower valve in the first pic, but, again, I am not completely sure what I am seeing here.

And in the second pic, this seems to be the typical cellular outer(!) shell of a radiolitid rudist, but everything is somewhat strange.

(I have only some first-hand experience with hippuritid and radiolitid rudists, but there are many more families!)

Franz Bernhard

[abyssunder]

It's definitely a rudist, with both valves partially preserved, and maybe there is or was a rudist colony. A polished transverse section (1-1.5cm below the commissure) may reveal more details.

 

excerpt from here

 

If the specimen is from the Aruma formation, then is probably from the upper part of the Khanasir Limestone, where the rudist biostrome is located.

 

" The rudist biostrome, approximately 2 m thick, is placed in the uppermost part of the Khanasir Limestone Member and consists mainly of Durania specimens. "

 

reference: S. Ozer & A. S. El-Sorogy. 2017. New record of Durania cornupastoris (rudist) from the Campanian of the Aruma Formation, Riyadh, Saudi Arabia: Description and biogeographic remarks. Journal of African Earth Sciences 129: 380-389

 

[drbush]

thank you all for the informative information 

[marguy]

+ 1 :rudist; probably a second smaller specimen on the right side (1st picture)

 

[fifbrindacier]

I agree with the rudist identification.

I'm glad to see fossils from that part of the world. We don't see ones very often.

[drbush]