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Tidgy's Dad

The thread http://www.thefossilforum.com/index.php?/topic/84678-adams-silurian/ was getting rather enormous, so I have decided to leave that one to deal with the Llandovery and Wenlock and put my specimens from the Late / Upper Silurian here, though I don't have a great deal of material from the Ludlow and Pridoli yet. However, I do still have some jolly nice specimens to show off here. 

Here are my other collection threads for the Cambrian and Ordovician ;


and :



In the mid 1980's, on the way home from one of my annual visits to the Hay-on-Wye second-hand bookshops, I managed to persuade my girlfriend at the time to take a bit of a detour and stop off at a roadcuttting just outside Aymestrey,, Herefordshire in the Welsh Borderlands. The rock here is the Aymestry (sic) Limestone Formation, part of the Upper Bringewood Beds and is Gorstian, Lower Ludlow in age, so about 426 mya and a little younger than the Much Wenlock Shale Formation. Many species of coral, trilobites and brachiopods found in the formation are the same as those found at Dudley, but the bed is noted for its massive numbers of the brachiopod Kirkidium knighti (was K. knightii),a lovely, large pentamerid. In fact, during my hour or so searching, I found almost nothing but this species, the only exception being a couple of Atrypa reticularis. The problem was that this limestone is thick and seriously hard, even the broken bits are generally huge, but I managed to obtain half a dozen reasonable specimens and about the same number of fragments. Over the years I have traded, given away or sold them, so that now I only have the best one left. Here is Kirkidium knighti :







It's a shame the tip of the beak is broken off :



I make index cards for all my fossils, this is the one I made for the specimens at the time, back in the mid 1980's :


And today's version :



There was a minor extinction between the Wenlock and the Ludlow, known as the Mulde event and it is often said to have primarily effected graptolites and conodonts, but it seems to me it had a massive impact on the bryozoan faunas of the time too. Gone are the varied stony stick and mound trepostomes that made up such an integral part of many faunas from the Middle Ordovician through to the Middle Silurian and even  cystoporid groups such as the Constellariidae became extinct at this time. Trepostomes and cystoporids did survive until the end of the Triassic, but were never as important again, the bryozoan faunas would start to become dominated by fenestrids in the Devonian, though they reached their peak of diversity and distribution in the Carboniferous. I will look closely at my limited number of rocks, but I don't think I have a single Late Silurian bryozoan. I know our friend @Mainefossils studies the Late Silurian Leighton Formation in microscopic detail, but I can't recall him posting any bryozoans. Are  there any, Asher, old chap? 



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Tidgy's Dad

An Austrian brachiopods species now! Yessss!!!.gif.b5d7fdb80a815b2939c0f9c908526993.gif

These are Septatrypa subsecreta from the K2 layer of the Eggenfeld Member, Kötschberg Formation, Rannach Nappe (Upper Nappe Group), Graz Paleozoic which Pridoli. The location was Eggenberg hill, near the hamlet of Eggenfeld, Gratwein, Styria, Austria. 

This specimen is 1.5 cm wide. brachial valve :



Pedicle valve :


A characteristic high, U-shape commissure but thin shell, no plications or thickened growth lines :


Beak :


Lateral views :



The second specimen, slightly smaller at 1.3 cm wide:







Interestingly, referring back to the previous post and the lack of bryozoans in the Late Silurian, the faunal list that I read for the Eggenfeld Member mentions crinoids (including Scyphocrinites, which I'll return to later in this thread), orthocerids, one bivalve, gastropods, indeterminate brachiopods a couple of corals, occasional trilobites and conodonts, but there is no mention of bryozoa. :zzzzscratchchin:


Thanks a million to the Frankly Fantastic @FranzBernhard for these little beauties. :b_love1: 


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6 hours ago, Tidgy's Dad said:

no mention of bryozoa.

It seems we are having a blind spot for bryozoa here. For example, the Eifelian Plabutsch-Formation is full with tiny tabulate corals (Thamnopora, Striatopora etc.), but bryozoa are very rare there. I am not sure that all of those tiny corals in that formation are corals.

Franz Bernhard

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Tidgy's Dad

Let's pop across The Pond for minute and have a look at some athyrids. These are Merista tennesseensis from Decatur County, Tennessee. They are Ludfordian, which is Lower Ludlow in age, about 425 mya. They come from the Brownsport Group, and probably the Beech River Formation. 

Here is the medium-sized one of the three that I have, courtesy of Rather Radiant Ralph @Nimravis :fistbump:













The smallest of the three :












Stunningly beautiful. 


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I saved the largest specimen of Merista tennesseensis for a separate post because


....as you can see, a great deal of the shell surface is encrusted with a bryozoan colony. It doesn't have any influence on the comments I made about bryozoa in the first two posts of this thread, as I was talking about the disappearance of the stick bryozoan mounds and 'forests', due in part to the partial annihilation of the trepostomes. This particular specimen seems to be an encrusting cystoporid, probably one of a few species of Fistulipora said to occur in the Brownsport Group. 







The contact of the overgrowth with the shell :



Close ups




I did as much research as I could on the bryzoan fauna of the Brownsport Group. The Brownsport Group used to be the Brownsport Formation with three members, but now it seems to be a group with three formations. The Beech River Formation is the lowest and a lot of the fossils seem to come from there in Decatur County. Then there is the Bob Formation. and finally the Lobelville Formation at the top. The bottom part of the latter is sometimes referred to as the Bryozoan Limestone as it is so rich in 'moss animals' and bryozoa occur in the other formations as well, even in 'stick' form. But they are mostly cystoporids, cryptosomes and a couple of fenestrids. There are a few trepostomes; small domes of a couple of species of Monotrypa, a tiny Leioclema and the quite common old Wenlock survivor Hallopora elegantula. But this last mentioned genera didn't make it out of the Silurian, perhaps finished off by the Lau Event, another minor extinction that occurred in the late Ludfordian. It has been noted that after this event, the stromatoporoids enjoyed an evolutionary radiation, but the bryozoans don't seem to have done the same.   

There is a wonderful variety of fossils in the Brownsport; sponges, corals, brachiopods, echinoderms and trilobites, but little mention of the bryozoa. 

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Tidgy's Dad

Back to Blighty and my early years of collecting now. 

Some specimens collected from a road cutting not far from Longhope and Hobbs Quarry where I found a lot of my wonderful Much Wenlock Limestone Formation material. 

This road cut on Longhope Hill exposes the Upper Longhope Beds, Leintwardine Group, which is the very top of the Ludfordian close to the junction of the Ludlow and  Pridoli epochs of the Late Silurian. 

This first rock is pretty much a brachiopod coquina in a fine grey-green siltstone matrix 



The vast majority of the brachiopods are Protochonetes ludloviensis. Though the chonetds had first evolved, probably from sowerbyellid strophomenid ancestors, towards the end of the Ordovician, they didn't become common until the Late Silurian when they began to dominate some of the brachiopod faunas, a sign of what was to come as they, and the later productids, would become increasingly important through the rest of the Palaeozoic.  I have a single specimen of P. minima from the Wenlock of Dudley, but these are much bigger and more numerous and represent a very successful genus in the Upper Silurian. 

Even though I turned the light of my microscope off, these photos have come out very orange. Strange. Here are lots of Protochonetes ludloviensis :


Many of these are internal molds of both the convex ventral pedicle valve and the concave dorsal brachial valve. The spines are limited to the posterior edge of the pedicle valve, so spine bases are seen only in a few specimens here. Note the diductor attachment points with the gap between. 
















The rock is pretty much made up of smashed up bits :







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Tidgy's Dad

There's always a rhynchonellid lurking about.

The other species of brachiopod in the above rock is Microsphaerirhynchia nucula. Two fragments and one decent specimen. I also have the same species from the Much Wenlock Limestone Formation as it, like many species from the Wenlock, was a widespread and long ranging brachiopod 


And continuing my interest in Late Silurian bryozoa, I don't remember noticing any in the field, but under the microscope ;


Maybe a bryozoan. I can only find another long lasting species, Ptilodictya lanceolata listed for this formation, as well as bryozoa indet. 


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These next couple from the Longhope Hill Ludlow are wonderful and fascinating. Book.gif.b930345a3a043bc0b82fb4fb61d003f3.gif

I saw a few of them along the bedding planes, but thought that they were just the end of a nautiloid and didn't want to just break off one chamber. Two were loose anyway, so I took those. 

It turns out that these are the internal molds of the orthocerid  Leurocycloceras whitcliffense, which was Orthoceras imbricatum and is still sometimes seen listed as L. imbricatum which was never valid. 

This is a fascinating species as the individual camarae always become detached after death so never have two or more chambers been found preserved together.  So these are not the ends of the animals, but individual segments / chambers / camerae from along the length of the mollusc shell. 


These horizontal lines are not septa, but pseudosepta and surface ornamentation


Most of the 'top' of this specimen has been broken away, unfortunately


We'll see the brachiopod again later on..................


The chambers were almost entirely filled with cameral deposits, with only a small gas filled area in the gaps between the hydroseptal and episeptal deposits :



The second specimen with sub-central siphuncle. Also note some lateral grooves running out from the siphuncle





And on the margins, on the next layer down, some episeptal vascular marks. :



Siphuncle ; 


I do wonder what they were eating though. It usually says orthocerids ate trilobites ans other arthropods, but there aren't any in this bed. Maybe soft bodied arthropods like Marrella? Nothing much eats articulate brachiopods through choice.  



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Tidgy's Dad

Here's some info and photos of the brachiopod attached to one of the specimens of Leurocycloceras shown in the post above. 

It's the orthid Salopina lunata. This genus is named after Salop, the old name for the county of Shropshire in England. It is found in other regions and occasionally other countries, but is very common in rocks around the Welsh borderlands. 

Though orthids are past their peak at this point, they will still play a part in many brachiopod assemblages through the rest of the Paleozoic. Good. 

Orthids are my favourite order of brachiopods, so it's nice to have one or two from the Upper Silurian. 



It looks like it could be broken free quite easily, but I'm not going to take the risk. I've only got the one and it's quite nice stuck to the bottom of the orthocerid chamber. 


A bit of the other valve is also showing :



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We also stopped briefly at a roadcut near May Hill in Gloucestershire, not too far from the last location and  I had a chance to have a quick shufty in some mudstones of the Upper Flaxley Beds that are also supposed to be Ludlow in age. Bit of a washout, as it started to rain. 

Here is my only find ; 




Back in the day, I recall reading that Dalmanites myops was found here, but I have since read that the species may be limited to the Wenlock and saw D. vulgaris listed from the formation. But that was still an old publication. So :shrug:


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Let's pop off to Poland now. 

This is a lovely example of a brachiopod 'coquina' sent to me by the Kind @Kasia

Like the specimen shown earlier from the UK, this one is packed with Protochonetes, though a different species, this is P. striatellus. Lovely to see these early chonetids appearing in numbers in some formations, a sign of what is to come. These are from the Pridoli Beyrichienkalk Formation, named for the ostracods that are common in some sections, though the common genus is actually now called Nodibeyrichia tuberculata. The location is Orzechowo, Poland. 

First though, I'll post a single specimen that Kasia sent me in a separate little rock: 


Beautiful. :b_love1:





Others on the reverse. 



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Tidgy's Dad

Here's the bigger 'coquina' of Protochonetes striatellus. Other brachiopods are also present. 


Oops.gif.79eaf315b545540e309ca27552b8f2e5.gifForgot the scale. 

Here you go: 


Also seems to be a small orthid to the top right here





Ostracod to the lower right?




part of a valve interior showing the pseudpunctate structure. 



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Tidgy's Dad

As was the case with the Protochonetes mortality plate from England, these P. striatellus are accompanied by some specimens of the very same species of rhynchonellid; Microsphaerdiorhynchus nucula. 



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Tidgy's Dad

The most common species in this rock after the Protochonetes is this spiriferid. Some sources suggest it is Delthyris elevata, but I'm far from sure that this could be correct. 









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Tidgy's Dad

Then there are a few tiny orthids, the first one might be Ptychopleurella bouchardi, I think. 




This last one's a stunner:b_love1: :



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Tidgy's Dad

Other critters in this Beyrichienkalk rock from Poland include this tiny cross-section of bryozoan. I can only find a reference to the cryptostome  Ptilodictya for the formation. The sort of triangular shape would fit, but I'm not at all positive. 


Then there is a bit of bivalve, could be a fragment of Pteronitella retroflexa found in this formation, but, again, I wouldn't bet on it. Pteronitella belongs to the group that led to pearl oysters, rather than 'true ' oysters. 




And finally, though I posted one above somewhere, here are a couple of possible ostracods. These are clearly not Nodibeyrichia, but could be a species of Leperditia. 


And another possible ostracod


Thank you again, @Kasia,, that rock was chockablock with marvelous bits! :fistbump:

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Now we shall come back to Morocco and talk about two very well known Moroccan fossils that are seen for sale everywhere.

First up is this one, given to me by an ex-student of mine


I've glued the broken tip back on since this photo was taken back in 2019. I dropped it. Still, no harm done as it's only a bit of the 'marble' so I haven't bothered with another photo of the complete piece. 

I expect we've all seen these "Devonian Orthoceras marble" specimens about. Not Devonian, not Orthoceras and not marble. 

See here for a more accurate description :


And here for photos of the marble in the shops of Erfoud:


I particularly love the Coke bottle. Great idea. 


Anyway, I've been doing some more research and chatting on and off for the last couple of years and have some updated information ;

This black limestone with orthocerids is actually called "The Temperoceras Limestone" or more formally the Filon Douze-Tafilet Bed, Tempoceras Limestone Section. Filon 12 is a series of mineral mines near the mountains of Taouz, but the beds outcrop for many kilometres heading north to the area around Tafilet between Erfoud and Rissani. and are extensively quarried near  Hassi Tachbit, east of Rissani, as I thought. The material is often then transported and sold to the folks in Erfoud for prepping, polishing and resale. The age is Lowermost Ludfordian, Upper Ludlow, so about 425 million years old. 

The orthocones found in this black rock include

Hemicosmoceras semibricatum,

Kionoceras doricum, criss-crossed ridges on shell exterior Can't be seen on polished specimens, of course. But it's slightly curved and can have swollen areas along the length. 

Kopaninoceras dorsatoides 

Kopaninoceras thyrsus

Temperoceras ludense By far the most common species. Is a member of the family Geisonoceratidae. as I thought. 

Plagiostomoceras pleurotomum  Long and thin, ridged.

Plagiostomoceras culter Long, thin and smooth. 

Parasphaerorthoceras sp. 

Sphooceras truncatum Short, fat and rounded at the posterior end. 

And rarely

Arionoceras canonicum

Subormoceras sp. 

Michelinoceras sp. 


Details of my specimens









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Tidgy's Dad

The second famous Moroccan fossil is the crinoid Scyphocrinites elegans. Sometimes incorrectly listed as Scyphocrinus elegans. 

Like the pervious specimen, this is often listed as Devonian, But is actually from the Pridoli, thus Upper Silurian in age. Found in what are known as the Scyphocrinites Limestone Beds.

It is an interesting crinoid in that it wasn't anchored to a substrate or other organism, nor was it free-swimming, but instead had a float called a lobolith from which the stem grew downwards. 

BizleyArt - Gallery - Category: Silurian - Image: 1505 Scyphocrinites  elegans

Sadly, I don't have a lobolith, but it's on my list. 

Surface collecting is now pretty difficult as the Tafilalt region in which they are found has been pretty much stripped bare and now they are collected by digging a vertical pit into the ground to a depth of up to five metres and then burrowing horizontally underneath the fossil layer and smashing bits off. These bits are then glued back together, usually in Erfoud. So, if you see a glued together plate, it doesn't mean it's a fake. Check to see that the stems, arms etc, continue naturally across the join. 

For more information and photos of huge blocks of them, see my threads linked in the post above. 

This is one I purchased a number of years back and is said to be from Djebel Issoumour near Alnif, which is about 65 miles south west of Erfoud and I believe this to be a correct possible location of origin. 


If you look closely, you can see that a section from immediately to the left of the stem at the bottom of the piece, stretching upwards and to the left to almost the top left of the specimen, has been crudely cemented onto the actually fossil. And it doesn't match up with the rest at all. This often happens and doesn't matter in the slightest as the actual main fossil is unbroken and entirely genuine, the bit added on is also genuine, but just from another species. If I wanted, I could break this off, but it's a good example of how these pieces are sold. Extra bits are often cemented or glued on to give the specimen a nice, balanced shape so as to be more aesthetically pleasing to potential purchasers. And these folks know what they're doing. 



Here you can clearly see the cement :





Notice the uniserial division of the brachials (arms) shown above and below. Each division has two arms emerging cleanly from a common ossicle. This separates the genus Scyphocrinites from Marhoumacrinus and Carolicrinus which are also found in these beds but are far less common. 


The arms are rich in pinnules.   



I did find some bits when I was scouring the dry gullies between Erfoud and the Hamar Laghdad. 

Rough bits are often not too impressive.


And this piece I picked up may have been discarded as unsaleable: 


This shows some columnals nicely



And a nicer one I found



I honestly did find a really, really lovely one, but it's been missing since early 2019. I think it may have got into one of my Devonian boxes. It'll turn up one day. 

This sounds like a tall story or the one that got away, I know. Tap.gif.47e280b8b3509c6c668b7405314db3e4.gif






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Tidgy's Dad

I'll finish as I started off; with a fossil I found in my youth. 

This one's from a trip to visit Welsh relatives when I was a child. 

We stopped off near the river in Bulth Wells for a picnic lunch and I got to search about in the shales on the edge of the river. I found one fossil.Pretty good since I had no tools and used bits of shale to batter other bits of shale. 

But it was my first graptolite, so I was extremely delighted. 

My research a little later seemed to suggest that it was Monograptus colonus, but recent investigation, forty years later, leads me to believe that I was probably correct but that the name has changed to Colonograptus colonus.







And that's it for my Silurian for now. I hope to get some more soon. 

Some really nice specimens in what I do have, so I'm very happy. Delighted.gif.794762784df7a3e388b2c14ee2bdda9f.gif

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