Cerithid(?) gastropods, shells replaced by carnelian, possibly late Cretaceous (Maastrichtian), western Sahara Desert Dakhia Region, Morrocco

[AllenAigen]

These came with only vague data: Sahara Desert, Morocco.  They are apparently three species of Cerithioidea. A similarly preserved gastropod (a stromboid) with a carnelian shell that I came across had good data: (late Cretaceous (Maastrichtian), western Sahara Desert, Dakhia Region, Assa, Morrocco).  They have fine white silica sand with silica cement infill and attached, making cleaning very difficult.    Any help would be appreciated.

 

 

[val horn]

Missing the photos 

[Tidgy's Dad]

Yes, no photos showing, I'm afraid.

Also, I think this means Dakhla. 

Assa and Dakhla in the Moroccan Sahara are hundreds of km apart. 

[digit]

Photos restored.

 

 

Cheers.

 

-Ken

[siteseer]

Those started appearing at the Tucson shows a number of years ago - maybe around 2010?  I was told they were agatized and were Eocene-age.  The site was said to be about 300km inland from Dakhla.  I have one that shows some translucence.  Because they are steinkerns, you might not be able to identify them to species especially if you can't find any specimens with shell remaining.

[digit]

27 minutes ago, siteseer said:

I was told they were agatized and were Eocene-age.  The site was said to be about 300km inland from Dakhla.  I have one that shows some translucence.  Because they are steinkerns, you might not be able to identify them to species especially if you can't find any specimens with shell remaining.

They certainly do appear to be agatized but they do seem better than most steinkerns that only preserve the inside texture of the gastropods. These appear to have infilled the cavity left by the shell providing a complete duplicate of the outside texture of the shell. True, there is no actual shell material so any latent color patterns on the shell may be long gone but the texturing should at least provide a chance to make these down to family or possibly even genus. They are likely outside of the scope of the Florida material that @MikeR knows so well but he may recognize these at some taxonomic level.

 

 

Cheers.

 

-Ken

[hemipristis]

Pretty!

[MikeR]

There was a similar discussion on the agatized Moroccan mollusks just last year.  I have seen them at shows and online as Cretaceous and sometimes as Eocene.  They appear Eocene to me; the top three as the same species of Cerithiidae, lower left a different species of that genus and the lower right in Potamididae.  I'm surprised that a European researcher has yet to describe the fauna.  Maybe someone has, but I just don't know.  I have a few species myself that I would like to identify.

 

Mike

[MikeR]

...also not steinkerns which are interior molds of molluscan shells.  Their preservation could be described as permineralization resulting in a silica pseudomorph, but you are looking at the exterior shell of the original gastropod.

[digit]

Thanks, Mike! A much better term than 'steinkern'.

 

 

Cheers.

 

-Ken

[Tidgy's Dad]

I understand that these beautiful gastropods are found occasionally in Algeria and a belt stretching though the Sahara in Morocco to around Dakhla on the coast. 

I also have not seen any paper describing them.