Carboniferous Corals From The Uk

[TqB]

It's about time I started posting some fossils . A couple of years ago, I got interested in my local Carboniferous (after a lifetime of collecting mostly Jurassic stuff). The corals quickly became an obsession and holidays are now planned around the possibility of new species...

They are mostly from northern England, a mixture of more or less in situ specimens and glacial erratics from the coast.

First up are Actinocyathus laticlavia and A. floriformis (A. laticlavia may just be a large form of A. floriformis). These are all from the basal Namurian (upper Mississippian equivalent).

There's a range of preservations; colony surfaces are hard to find (first specimen), blocks to section are more common and hard to resist!

A. laticlavia

A. laticlavia - sectioned river pebble, partially silicified in limestone

A. floriformis - in dolomitic limestone with haematite staining

Edited August 1, 2013 by TqB

[t-tree]

Beautiful specimens keep them coming.

Cheers John

[Terry Dactyll]

Tarquin....Fabulous....Great to see and nice polishing...

[TqB]

John & Steve - thanks! - a few more to come as you know .

Some more Actinocyathus, all from NE England, basal Namurian:

This rough chunk of A. laticlavia from an old quarry shows a lot of voids, wasn't sure if a section would polish well but was pleasantly surprised:

This an 8"x6" chunk of A. floriformis, about a third of a dome shaped colony. The surface was badly worn so it's been polished:

2.25" beach pebble, A floriformis:

[Auspex]

This is all very cool!

[Ridgehiker]

Thanks. Most of my formal paleo work in geology revolved around biostratigraphy using Carboniferous and Permian corals.

I also really like them. There's something aesthetic about them when examined closely.

In study, we slice them and use either polished thin sections or take a series of acetate peels to study the minutia of the septa.

If you ever want a thin section, happy to send you one.

[Beach Boy]

Hi Tarquin

So intricate and beautiful.

A pleasure to look at, you must get a buzz when you find one.

Regards

Dave

[Terry Dactyll]

Fabulous detail (and polishing).... It would be good to see some examples from around the world.... It would make a brilliant topic....

[TqB]

Thanks very much, everyone!

Northstar - many thanks, I agree the combination of taxonomic rigour and aesthetics is very appealing! I've just started doing some acetate peels but need to practice...

Steve - thanks again! - there's loads of good stuff on Frank Menser's "show us your coral" thread .

Edited August 3, 2013 by TqB

[TqB]

This is also Actinocyathus laticlavia despite the corallites being separate (phaceloid) - it's a growth form that occurs at the edges or top of the "normal" cerioid colonies.

This makes it effectively indistinguishable from the genus Lonsdaleia (which it used to be called) - very awkward in practice but the two genera are official at the moment...

Here's the first specimen of that growth form that I found, thinking it was Lonsdaleia duplicata but it probably isn't.

It's partially silicified and naturally etched which shows the delicate outer dissepimentarium well.

One side of it is mineral stained from the stream it was in, near its source quarry and copper rich lead mines.

Edited August 3, 2013 by TqB

[TqB]

This one is out of the sequence I was going to do but I only found it yesterday and am still excited by it.

It's rare at this horizon (Namurian Great Limestone, N.E. England - more common a lot earlier) - and nicely preserved. I've only found one other in hundreds of hours of searching.

I believe it's an Axophyllum but don't have a species for it yet.

This section, taken from just behind the weathered surface in the first photo, shows traces of the lonsdaleoid (big and bubbly) dissepiments around the outside - these are delicate and very often lost prior to fossilisation.

For comparison, here's my only other specimen - the dissepiments are better preserved in this one.

Edited August 5, 2013 by TqB

[Ridgehiker]

You 'earned' your find.

Thanks for the great photos. Any camera tips? Your photos are better than some in journals. I dip the coral in diluted hydrochloride acid for a few seconds then rinse really well. This brings out more detail but your specimen already has a lot.

About naming your find to species. It's really difficult to identify a coral to species level without a cross section to study the minutia of the parts of the septa. Even then it can get 'iffy'. This is why corals are important in dating some ages of rocks. The subtle evolution of a genus can be followed in time and matched to co-existing conodonts, foraminifera, etc.

We have a lot of Namurian exposures in our Alberta Rockies. However the fossil province is more from Russia across the Arctic down through Alberta and into parts of the Western USA. The British fauna is slightly different as is that of the Namurian in the Eastern USA (Mississippian)

There is a really interesting old volume from the Paleontological Society. Great drawings. It's from 1850 and called 'British Paleozoic Corals'. I picked up a copy when visiting the UK. It's dated of course but gives a foundation for a lot of late studies.

Curious if you are finding any phaceloid tabulate corals such as syringopora?

[Terry Dactyll]

Beautiful.... I've seen the copper church roofs green with the copper oxide that forms and now I have seen a fossil coral turned green by copper.... thanks for sharing...

[TqB]

Steve, thanks again - the green staining happens quite often in these streams but that's my favourite so far.

Northstar - thanks for your kind comments; I'll try the HCl trick - perhaps a photo before doing a peel would be a good idea?

My camera's just a Canon SX20IS, and I use a cheap overhead tripod with a pair of 55W 5400K studio lights. The camera's set to macro or supermacro and a delay of 2 seconds to reduce wobble. That's about it really - then Photoshop to sharpen up if necessary.

I think I have the monograph you mention - Edwards and Haime? - and I agree, the illustrations are stunning - I might put a few on here with the relevant specimens. (Oddly enough, mine came from the USA... cheapest available at the time.)

Yes, Syringopora is generally quite common - I don't know of any other Carboniferous phaceloid tabulates in Britain. A quick glance through the Treatise shows me that you have a few others over there (Pleurosiphonella etc.). I'll see if I have any to photograph.

The only other tabulates I've collected so far are "Aulopora", Cladochonus and various Michelinia including a Namurian one (several specimens) that doesn't seem to have been recorded before.

[Kosmoceras]

These are really special Tarquin, looking forward to seeing more of your collection.

[TqB]

Some Lithostrotion next - in the current sense this is restricted to cerioid species. There are four commonly identified ones in the British Visean/Namurian. There's a tendency for the corallites to reduce in size as you move up the sequence.

This is the earliest and generally largest - the species are determined statistically on number of septa and diameter of tabularium (rather than diameter of the whole corallite) - in practice, it's reasonable to count the maximum number of septa in a few mature corallites.

Lithostrotion araneum, Holkerian, N.W. England.

As found:

Surface partially ground (this was before I got a saw which is much quicker!):

[TqB]

Thanks, Thomas! - here's the next Lithostrotion, a large corallite L. vorticale. I can't find any corallites with more than 24 major septa but that puts it at the top end for this species. It's only one or two septa short of the L. araneum in the last post - I don't actually know if the series is continuous or if the species are discrete.

This is a glacial erratic from the Yorkshire coast and it will have come from north or west of there.

It's supposed to be restricted to the Holkerian and Asbian stages.

Pebble as found, can be hard to spot unless they're wet, this one does show a worn calicular surface but they often don't:

Cut & polished:

Edited August 8, 2013 by TqB

[DE&i]

Hi Tarquin,

Stunning finds...the only down side on my part is the serious stiff neck I'll probably develope as I walk along the coasts if the IOW looking at all the pebbles ...thanks for showing finds.

Regards,

Darren.

Edited August 8, 2013 by D&E

[Terry Dactyll]

I like collecting in the rain but I never see anything like that... mores the pity...I'm enjoying this thread unfold and hear the stories behind the finds...

Keep them coming....

[Ludwigia]

Not only very nice but also quite informative. I haven't come across much in the way of carboniferous corals as yet in my wanderings, so it's good to see such fine samples for comparison with my Devonian ones.

[DE&i]

Hello Tarquin,

Ive a PDF file you may be interested in or have all ready :

The authors for this are Duncan, P. Martin (Peter Martin), 1821-1891 and Milne-Edwards, H. (Henri), 1800-1885.

Titled : A monograph of the British fossil corals. 2d ser (1866)

There are corals from the Tertiary and Cretaceous UK from Edwards and Haime A monograph of the British fossil corals (1850)

also corals from Oolitic and Liassic formations UK .

Regards,

Darren.

[TqB]

Darren - thanks for the kind comments - I do have that monograph and the illustrations are stunning!

Steve - thanks, perhaps Weston super Mare in the rain?

Roger - thanks, I hope to collect some Devonian ones myself (in Devon!) - as I'm sure you know, the origins of most Carboniferous rugose corals are rather obscure following the Devonian mass extinction so comparisons are intriguing.

Some more Lithostrotion vorticale, all Yorkshire coast erratics:

A pebble that I ground and polished, very laborious and I've stopped doing it (carpal tunnel!);

A rather recrystallised one still showing the basic structure nicely:

Better preserved corallites in this one with calcite veins that makes an attractive cut pair (I confess I can't stop picking these up - they're of little scientific value but look good on the shelf!):

Edited August 9, 2013 by TqB

[TqB]

I've neglected this thread for a while but now have a better camera and lots more specimens .

I don't collect that many solitary corals but this is an agatised Siphonophyllia sp. from the Arundian (mid-Mississippian) of N. W. England.

I like the blue preservation of the large dissepiments that help characterise this genus; they're often damaged and lost before fossilisation.

[Ammojoe]

Lovely specimen Tarquin, and great photography as usual - thanks for sharing.

[TqB]

Thanks, Joe! - you'll have seen this next one...

It's Siphonodendron junceum, probably the commonest Carboniferous coral in many places but I haven't come across another preserved quite like this, in an iron rich limestone nodule.

Brigantian (upper Mississippian), Northumberland coast.

Scale in mm, corallites about 2mm diameter.

Edited June 8, 2014 by TqB