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Post by pleecan (Peter Lee) on Feb 6, 2011 19:46:39 GMT -5
Hi Joe, Lucy or Any one else: Okay I am back... I know you are a renowed soft bodied preservation expert... are you able to comment on this fossil that looks like a snow flake? Cambrian material.... part and counter part Discussions on other forum indicate this could be some sort of proto sponge.     |
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Post by Joe Botting on Feb 6, 2011 21:37:08 GMT -5
Helloooo! We still exist! Just not really on here - there has simply been too much else going on, and this forum, I confess, has dropped off the radar. I'm always on the end of email (the acutipuerilis one), however. The good news is we're back in research, having moved to Nanjing (China) for two year post-docs, and I've started to update the early sponge record in earnest.
This one here, though, is not convincing, I'm afraid. The symmetry and branching pattern actually suggest a dendrite to me, and it certainly doesn't fit the primitive sponge bodyplan. I saw on the fossil forum suggestions of an isolated spicule, but oxyhexasters are truly minute and virtually never preserved due to rapid dissolution - and if it was preserved, it would not be flattened onto a plane like this one.
If it's not a weathered dendrite, then the hexaradiality is confusing; I would look at some group of cnidarians as a possibility... but as I say, the branching pattern in the arms screams dendrite at me.
All the best,
Joe
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Post by pleecan (Peter Lee) on Feb 7, 2011 11:54:01 GMT -5
Thanks for the Reply Joe!!! I have both halves of the fossil. No weathering has taken place as I have both matching surfaces.... Good to see you back! Great that you are back in China... lots of activity there same with Morocco Ordovician... I might contact G. Young... may be a primitive Jellyfish!
Thanks a bunch...
Peter
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Post by Joe Botting on Feb 8, 2011 6:56:47 GMT -5
Hang on a sec... these Cambrian deposits in China are just like the Fezouata - the rocks are deeply weathered, down to several hundred metres in places. They don't need to be fractured - ther weathering just happens through the pore spaces. The colouring is clearly oxidised, which unless it was crystallising as hematite in the first place, means it's been weathered. However... it looks from weathered framboidal pyrite (lots of isolated spherules, overlapping in much of it), which does tend to indicate soft tissue, as pyrite doesn't (to my knowledge) form dendrites. It's one of those things where you really want another... but it wouldn't surprise me if they were there but have been overlooked. Graham might well have a different take on it, so certainly worth a try! (in other words... dunno!)
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Post by pleecan (Peter Lee) on Feb 8, 2011 8:43:51 GMT -5
Yes Joe... you are so right the rock matrix is porous thus a fossil can weather interally unless the matrix is moisture imprevious like chert or dolostone... I learned something new today! Thanks..... for you insight Joe... always good to exchange ideas!
Peter
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Post by pleecan (Peter Lee) on Feb 9, 2011 11:32:30 GMT -5
Hi Joe: I got a response from Graham this morning and he is of the opinion that it is NOT a Jelly Fish.... so it is not a sponge and not a jellyfish... hmmm. An unknown at this point..... anyone else have an idea?
PL
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Post by pleecan (Peter Lee) on Feb 9, 2011 22:25:35 GMT -5
Photos have been sent to NHM in UK for there opinion.
PL
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BillG
New Member
Posts: 28
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Post by BillG on Feb 10, 2011 4:59:28 GMT -5
They might take a while to get back to you Peter.
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Post by pleecan (Peter Lee) on Feb 10, 2011 10:12:00 GMT -5
Thanks Bill for your help.
Peter
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Post by dinodragon on Feb 14, 2011 20:55:35 GMT -5
The matrix looks somehow different from the most of ChengJiang material. The grains are coarser than fine clay.
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Post by pleecan (Peter Lee) on Feb 14, 2011 21:44:06 GMT -5
The gain patterns is under magnification thus looks coarser... comparison of other matrix from Chengjiang appears normal... may be a tad coarser but not by much....
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Post by pleecan (Peter Lee) on Feb 21, 2011 14:14:33 GMT -5
Here is the latest comments:
"I’ve passed your enquiry around colleagues in the Palaeontology and Mineralogy Departments and gathered some comments below. As you can see, the result is similar to that on the forum – there are differences of opinion but the majority come down on the side of a dendritic marking of some kind rather than a rare fossil.
“This doesn't have the surface relief that one expects in a Chengjiang fossil. It looks to me like it is iron oxide staining of the sediment surface without necessarily tracing any biological structure (a radiating one or otherwise). My vote would be that it is abiological.”
Dr Greg Edgecombe, Arthropod researcher
“I would guess that it is inorganic and akin to a manganese dendrite.”
Dr Paul Taylor, Bryozoan and sponge Researcher
“My personal opinion is that it is a haematite dendrite thing and not a fossil.”
Dr Tim Ewin, Invertebrates and Plants Curator
“Could be the proximal end development of a hemichordate – excpet that they usually have multiples of four, not six.”
Prof. Richard Fortey FRS, Scientific Associate and Trilobite Researcher
“Mineralogically, this looks like a hematite rich stain. It don’t know why it should form the pattern that it has unless it had some biological control, or it was just pure serendipity. Hematite does had a 3-fold symmetry so a 3 or 6 rayed arrangement might not be unexpected, although there is no obvious suggestion this is so here. I’d go for hematite rather than Mn-dendrites, as the latter are generally black, and this is a typical hematite colour. I can’t tell what the rock type is, but it doesn’t really look sedimentary. If I had to guess I’d say it was a metamorphic rock, perhaps a schist, but maybe the image is misleading.”
Mr Peter Tandy, Mineral Curator
I hope this is of use and interest despite being somewhat inconclusive. Beyond this, I can only suggest trying to contact someone who has a very in-depth specialism in this particular fauna.
Regards,
Luanne Faulknall
Earth Sciences ID Officer
Centre for UK Biodiversity
Natural History Museum
Cromwell Road, London
SW7 5BD, UK."
end of quote
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Post by Joe Botting on Feb 23, 2011 9:22:24 GMT -5
Thanks for letting us know. It's obviously gone to some of the best in a variety of fields, so it looks as though if it is a fossil, we'll never be able to be sure. If Peter Tandy isn't 100% sure then that does suggest it might have some biological control... but you;re going to need another one to get any further, I'm afraid!
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Post by pleecan (Peter Lee) on Feb 23, 2011 13:14:27 GMT -5
My EPI Olympus 20x microscope objective has finally been utilise with the help of EPI to RMS adapter unit that just arrived a few days ago... Actually I re-imaged and resubmitted the pictures to NHM .... this time at 200X magnification and yes there are finger hook like projections to be seen... It is biological in origin... there is too much order and symmetry to be random chance ... we have a low entropy system here.... meaning biological. 200X center portion     see upper right hand side for 6 finger like projections. Random shots elsewhere     You actually can see hook like projection that is clearly biological in origin and not a iron stain at 200X magnification Peter |
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Post by Joe Botting on Feb 25, 2011 9:05:41 GMT -5
Hmmm... got to say I think you might be getting carried away a little bit here, Peter... but perhaps only a *little* bit! ;-)
The only structure that looks really biological in the close-ups is that little hook-shaped thing, and the texture is slightly different to the remainder - which *could* be interpreted as more recalcitrant organic material. It could just be a bit of random mineral gubbins, but on the other hand, you might be right. Possibly.
I'm actually starting to think this could be some sort of alga, with fan-shaped branches from a central holdfast. The overall symmetry would make more sense than an animal, along with the differences between the branches, and the preservation would be reasonable. If so, there should be more of them out there somehere - seaweeds are usually gregarious.
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