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Buzz
I'm going to have to half this fossil to see what's there.....
might have to find someone with the right equipment to slice her...
I think it may be too hard for me to tackle
Anne
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Buzz
Hi..found these babies at Ravenscar on 2 separate occasions...not sure what they are
nearest description I can find is Mawsonites....am I on the right track?P1210754.JPG 
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Buzz
P1210758.JPG 
the last 2 are from Coniston at the weekend...I know theyre a bit messy
does anyone have any ideas...they are in the blue slate from AshgillP1210766.JPG P1210769.JPG 
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AndyS
Buzz,

Theyƒâ€š‚´re most probably Palaeosemaeostoma, a "medusiform burrow" according to Seilacher -
i.e. a trace fossil, not a jellyfish.

Not sure what the Coniston / Ashgill fossils are.

AndyS


Edited by AndyS 2014-10-04 19:02:39
Visit my liassic ammonites (+ other fossils) blog at andysfossils.com
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Buzz
Thanks AndyS...I thought maybe a plant of some sort
there are quiet broad segments in the bulbous bit
fossils are hard to find in this area...tho I did find my first
Trilobite tails in some slate...so was made up
Anne
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acutipuerilis


Interesting trace fossils... or pseudofossils! I do wonder whether these are concretionary growths around a single vertical burrow, instead of cnidarian resting traces; they seem too 3-D for that interpretation. The lobes on the larger one are also very irregular, which would fit with mineral... if you're willing to cut one in half an polish it, you might well find some interesting things.

The Coniston ones are rather nice orthocone nautiloids.

http://oldasthehills.proboards.com/index.cgi (For when you can't get enough trilobites, sponges, and squidgy blobs...)
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Buzz
thanks Joe...yes the big one at least seems a bit complex for burrows tho they do match the Seilacher diagrams...they are both quite weighty which makes me think maybe mineral. Yes I might slice one and have a look!

Good I.D. the nautiloid...that hadnt occurred to me..it does look very similar. I might have a go at prepping it...tho it looks quite friable ..that was a pic of back  and front so you can see it's not so stable.
 
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AndyS
Joe,

You misunderstood - Seilacher said these have nothing to do with jellyfish, according to his interpretation these are burrows of an unknown organism.

A. Seilacher : Trace Fossil Analysis, Springer 2007, p. 136

AndyS
Visit my liassic ammonites (+ other fossils) blog at andysfossils.com
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Buzz
Hi AndyS,
yeah I got the bit about burrows...was amazed by the Seilacher diagrams...they seemed spot on!
I had thought it highly unlikely that they were jelly fish...just couldn't figure out what they could be.

Acutipuerilis idea that they may be some sort of mineral concretions around a burrow sounds plausible especially given their weight.

yeah reading back my last post...it was a bit confusing
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acutipuerilis


Aye, I misread 'medusiform' for 'medusoid!' - sorry about that. There is a lot of ambiguity over trace- versus pseudofossil in these things. Seilacher (sadly he died earlier this year) was a bit of a maverick genius in many ways. I got an insight into his thinking by staying with him for a few weeks, and he basically worked on constructional engineering principles, rather than biological or chemical ones. Not saying he's wrong, but just that it's worth bearing in mind that his interpretations frequently pushed the boundaries a bit. What little I can find on Palaeosemaeostoma is sadly in Russian:

http://ashipunov.info/jurassic/j/gerasimov,1980_jellyfish.pdf

But yes, it does look identical, whatever it is! I'd definitely like to see the internal structure, which should let us work it out.

http://oldasthehills.proboards.com/index.cgi (For when you can't get enough trilobites, sponges, and squidgy blobs...)
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