Cornuella, a very rare ornamented cyrtocone, Carboniferous, UK

[TqB]

This post is prompted by finding a near complete specimen of Cornuella cf. ornata, Brigantian, (Mississippian) shale above the Four Fathom Limestone. Co. Durham, UK. 

 

Apart from one fragment from the early 19th century I can find nothing comparable in the UK literature.. 

Fine specimens have been found in Russia from the Serpukhovian Stage (upper Mississippian, slightly later than this one).

See at the end of the post for both of these.

 

I previously had just a single, small fragment which was a mystery. A friend then gave me another fine 3D fragment from Scotland and this was kindly identified by a Russian collector on another forum (@valh on here,  thank you Valerij!). 

Details on TFF here: ornamented orthocone, scotland

 

Here's my new specimen which was in a wet, disintegrating mudstone.

I held it together in the field with cyanoacrylate then dried it for a few days. 

Prepping was with a scalpel under a 20x microscope, consolidating the matrix and shell with 5-10% paraloid as I went along. (Took about 25 hours I think.)

It's too fragile to risk air abrading - the shell was already gone from the living chamber and barely attached to the rest of it.

 

As collected:

 

The first UK reference is Orthocera rugosa, Fleming 1828, a fragmentary specimen with a description only.

This was figured in 1835 in Phillips "Illustrations of the Geology of Yorkshire" Vol. 2, plate 21, no. 16 naming it as Orthoceras rugosum Fleming.

I can't find another figured specimen in UK literature. (Phillips simply gives "Northumberland" as the locality - the next county up from Durham.)

 

 

Below is the plate of Russian Cornuella ornata (Eichwald) from Shimansky, 1968.

(Shimansky, V. N., 1968: Kamennougolniye Orthoceratida, Oncoceratida, Actinoceratida i Bactritida (Carboniferous Orthoceratida, Oncocerida, Actinoceratida and Bactritida). Akademiia Nauk SSSR, Trudy Paleontologicheskogo Instituta, vol. 117, p. 1–151, pls. 1–20. (in Russian).

 

And here's my original mystery fragment:

 

 

 

 

 

 

 

 

 

 

[TqB]

One more specimen: while prepping the previous one, I suddenly realised that a flattened fossil from the same bed that I'd had for years and IDd cursorily as a Calamites tip is in fact a compressed Cornuella impression.

Making three from here. 

 

 

For completeness on this thread, here's the beautifully detailed Ayrshire fragment (Dockra Limestone) that was posted before. The collector who gave it to me said that other, not so good, fragments were in the same shale bed but it has now been quarried away (commercial quarrying, not collectors...).

It's 26.5mm long.

 

[doushantuo]

Awesome!

[doushantuo]

I'm looking into the possibility that this is a (hypseloconid) monoplacophoran.(NOT saying that it is,BTW)

Edit:Stinchcombe mentions C.Parva as a monoplacophoran,that's why.

(he also seems to describe Orthoconus striatus ,BTWj

Russian taxonomy in those days might have been different from the rest of the world for geopolitical reasons

Large nowakiid or dacryoconarid of some kind??

[TqB]

26 minutes ago, doushantuo said:

I'm looking into the possibility that this is a (hypseloconid) monoplacophoran.

Edit:Stinchcombe mentions C.Parva as a monoplacophoran,that's why.

(he also seem to describe Orthoconus striatus ,BTWj

Russian taxonomy in those days might have been different from the rest of the world for geopolitical reasons

Tentaculitid of some kind??

 

I've seen that, Cambrian/Ordovician things, and if the genus is Stinchcomb 1986 he was predated by Shimansky 1968.

This one's definitely a nautiloid , the last couple of camerae before the living chambers are clear in my specimen. 

And Fleming's specimen, with chambers and siphuncle. (Not come across tentaculitids in the Carboniferous?)

[doushantuo]

Okay,after all you have the specimen

Judging from fig 10 in the Shimansky,it would have to be cephalopod,I guess

My ability to read Cyrillic is very limited,alas

[TqB]

Mine's non-existent. I back-tracked from the beautiful specimens and details on ammonit.ru, using Google Chrome (search Cornuella ornata images if you haven't already).

http://www.ammonit.ru/foto/46254.htm

[TqB]

1 hour ago, doushantuo said:

Awesome!

 

And thank you!

[jewelonly]

Congratulations on this important find, Tarquin! Your ability to prep such fragile specimens so wonderfully is amazing to me!

 

Leah

[doushantuo]

And kudo's for the research,very thorough.

Amazing prep effort too.

 

Mouthwatering fossil ,but I didn't expect any less from the Collections Manager

[Miocene_Mason]

That's beautiful fossil, not to mention the rarity! Nice find!

[TqB]

1 hour ago, jewelonly said:

Congratulations on this important find, Tarquin! Your ability to prep such fragile specimens so wonderfully is amazing to me!

 

Leah

Thank you, Leah, much appreciated!

 

57 minutes ago, doushantuo said:

And kudo's for the research,very thorough.

Amazing prep effort too.

 

Mouthwatering fossil ,but I didn't expect any less from the Collections Manager

Thanks again - and for your discursive input as always! 

 

52 minutes ago, WhodamanHD said:

That's beautiful fossil, not to mention the rarity! Nice find!

Thank you! The ornament is certainly remarkable.