Graptolites from Wales

[DE&i]

Quoted from the excellent ukfossils.co.uk website below, to help describe these fossils found forty years ago and currently going through some much needed TLC from team DE&i

 

 

“These graptolites (pictured above) Didymograptus murchisoni are from Abereiddy Bay, Pembrokeshire in Wales and they are a species known as the ‘tuning-fork’ graptolite. They existed for only a relatively short period of time, during the latter part of the Middle Ordovician, about 470 to 464mya. Therefore, it used as an index fossil for this period of time, which geologists refer to as the Llanvirn stage 9 after a farmer’s cottage on the lane leading to Abereiddy).”

 

 

Now judging by the paragraph above and the newspaper pages that this large box of shale’s was carefully wrapped in. You kind of get this sense of wonder, for some further interesting, perhaps not so apparent fossils that theses shale’s could contain.

 

I’ve excitedly established that there is indeed hundreds of Didymograptus murchisoni graptolites packed into these shale’s.

 

Continued in reply :

[doushantuo]

[DE&i]

Continued : 

 

At the moment under closer inspection of the same shale’s (but I’ll still look deeper) I’ve discovered to unknown fossils that I can’t seem to find a match to help with further research. Any assistance with the fossil photos below would be very much appreciated indeed.

 

 

 

 

 

 

[westcoast]

Is that last image the structure of graptolite zoothecal  tube preserved in 3D? That would be rare. The first  images may be overlapping superimposed fragments? The others are a tiny bit like arienigraptus but I'm just guessing. Either way that is a fantastic collection!

[doushantuo]

Isograptid manubria?

Glossograptids?

[TqB]

I believe the last one is the border of a trinucleid cephalon. They do occur there occasionally - I found a similar, more complete one but no longer have it I'm afraid.

[DE&i]

2 hours ago, westcoast said:

Is that last image the structure of graptolite zoothecal  tube preserved in 3D? That would be rare. The first  images may be overlapping superimposed fragments? The others are a tiny bit like arienigraptus but I'm just guessing. Either way that is a fantastic collection!

 

Thank you @westcoast for your very helpful descriptions . That's interesting that you may think there is some sort of overlapping, I find it intriguing that they seem to have the same pattern to them, as these are just two I picked out. And i'm sure if I split some more shale's there would be more of these odd almost uniform shapes.   

 

[westcoast]

To be clear I wasn't suggesting the latter images were overlapping just the first two of the last batch of images which look a bit different but like I said I'm guessing so hopefully some graptolite expert will chime in shortly 

[DE&i]

59 minutes ago, TqB said:

I believe the last one is the border of a trinucleid cephalon. They do occur there occasionally - I found a similar, more complete one but no longer have it I'm afraid.

 

Thank you @TqB your description fits perfectly as like you say, this is indeed a fragment of  Trinucleus fimbriatus (pictured below is a museum example). Among the rarer fossils recorded at this location are planktonic trilobites called agnostids Trinucleus fimbriatus are these one and the same would you know. 

 

 

[DE&i]

35 minutes ago, westcoast said:

To be clear I wasn't suggesting the latter images were overlapping just the first two of the last batch of images which look a bit different but like I said I'm guessing so hopefully some graptolite expert will chime in shortly 

 

Sorry for the confusion @westcoast and thank you for pointing this out.

[TqB]

5 minutes ago, DE&i said:

 

Thank you @TqB your description fits perfectly as like you say, this is indeed a fragment of  Trinucleus fimbriatus (pictured below is a museum example). Among the rarer fossils recorded at this location are planktonic trilobites called agnostids Trinucleus fimbriatus are these one and the same would you know. 

 

 

 

Trinucleus isn't an agnostid if that's what you mean (google agnostid trilobites for images). I haven't seen any agnostids from Abereiddy but I've only ever spent a couple of days there. Trilobites of any sort are rare there (as usual with graptolitic shales).

[TqB]

I wonder if the others are crystal rosettes, though they are the same colour as the graptolites...

[doushantuo]

I think those are juvenile isograptid manubria,slightly reminiscent of I .Dumosus

edit: for "are" please read "could be"

[abyssunder]

Very interesting specimens!

A possible resemblance (as Tarquin suggested - "crystal rosettes") could be something similar to this, but the geological age and the dimensions are not proper.

 

pictures from here

[Wrangellian]

Just a couple weeks shy of 40 years out of the ground! (A couple days before my brother's birth and I was pretty young...)

I acquired a small specimen of this from an ebayer in UK some time ago, but yours is/are better.

Is that quote saying that the Llanvirnian was named for a farmer's cottage along that lane? And that all tuning fork graptolites are restricted to that stage, or just that particular species of tuning fork?

[doushantuo]

Because of ,among other things,graptolite provincialism,a lot of biostratigraphic zonations tend to have diachronous F(irst)O(currence)'s and L(ast)O's or FA(ppearance) and LA's

 

In the type artus  and bifidus MIGHT be restricted to their eponymous zones

 

to be absolutely pedantic:the ending -"ian"is erroneous.

[doushantuo]

type-specimen-of-didytus-murchni.pdf

[westcoast]

15 hours ago, doushantuo said:

I think those are juvenile isograptid manubria,slightly reminiscent of I .Dumosus

edit: for "are" please read "could be"

Given the scale provided are they not too large to be juveniles?

[doushantuo]

yeah.

I must say it's a while ago since i read any Jenkins

Come to think of it,I think synrhabdosomes for these objects might be more likely

[abyssunder]

J. C. Gutierrez-Marco, A. C. Lenz. 1998. Graptolite synrhabdosomes biological or taphonomic entities? Paleobiology, 24(1), pp. 37-48

[westcoast]

Hats off to @doushantuo and @abyssunder. That's something I didn't know this morning.

[DE&i]

Dear all,

 

Thank you for you valuable input, I've made notes from all your replies. And will process the information to the best of my abilities. In the hope of shedding more light on these intriguing finds. 

 

And of course post back here any additional information I come up with along the way.

 

[DE&i]

While we all wait for further expert opinions. Enjoy a paleocast on graptolites.

 

http://www.palaeocast.com/episode-71-graptolites/