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Shamalama

Algal Filaments?

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Shamalama

While going through a box of material that I'd collected from the late Silurian (Pridoli to Lochkovian) aged Keyser formation I found these odd fossils. They look very filamentous but don't seem to form any sort of cohesive fossil that I recognize.

Specimen 1

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Closeup

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Specimen 2 - This one looks a little polished because at one time I think I tried used my Dremel tools brushed to try and clean matrix off.

post-1408-0-80047700-1319407179_thumb.jpg

Closeup

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The rock it is found in is a thin bedded limy shale that was deposited in a lagoonal environment similar to the back bays of the modern East Coast shoreline. Do you think these are fossils of algae? I can't find anything in my (admittedly sparse) library that indicates such fossils are found in the formation. I know in other parts of the formation one can find Stromatoporids but those are sponges and look nothing like these fossils. I'm ruling out trace fossils also as they have too much texture and are often "flowing" in one directions rather than random like most ichnofossils.

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tracer

kinda looks like broken-up pieces of "woody" material all jumbled together. the lines and definition of the edges of each piece are more straight and distinct that i would expect from algae.

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ashcraft

Based on the age of the rock, I would say a stromatolite. They look very similar to petrified wood, but where around in the Silurian.

Brent Ashcraft

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Auspex

Based on the age of the rock, I would say a stromatolite...

That, or calcified algae?

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Indy

I've seen these shapes before but can't remember where :unsure:

I don't see algae or stromatolite

I'm leaning more towards remains of plant material

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piranha

Looks like a terrestrial vascular plant Dave. The Keyser Fm is quite large. Where did you collect it?

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Shamalama

Piranha - I collected them from an old quarry near Mapleton, PA which is about as close to the middle of Pennsylvania as you can get.

Brent - I'm not thinking Stromatolite because of the length of the strands and the lack of layering. Stromatolites are found in the Keyser but usually as spherical or rounded shapes. If you have any examples that look like what I found I'd like to see them.

Tracer, Indy, Piranha - Hmmm... Early vascular plants? I suppose it's a possibility as it was a lagoonal environment and the age of the rocks is within the range for early terrestrial plants. Personally I'm leaning towards Calcified Algae like Auspex suggested.

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Indy

Piranha - I collected them from an old quarry near Mapleton, PA which is about as close to the middle of Pennsylvania as you can get.

Brent - I'm not thinking Stromatolite because of the length of the strands and the lack of layering. Stromatolites are found in the Keyser but usually as spherical or rounded shapes. If you have any examples that look like what I found I'd like to see them.

Tracer, Indy, Piranha - Hmmm... Early vascular plants? I suppose it's a possibility as it was a lagoonal environment and the age of the rocks is within the range for early terrestrial plants. Personally I'm leaning towards Calcified Algae like Auspex suggested.

These shapes are not something new...

I'm wondering if anyone has any images of Calcified Algae for comparison

:zzzzscratchchin:

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tracer

it isn't a direct analogy but i've got some fossil plant material from younger strata that is similarly "jumbled". i've also seen a fascinating jasp-agate with the equivalent of a plant breccia sort of look to it. i just sort of wonder if the environment couldn't have caused the cellulose to start breaking down and coming apart and the material got agitated somehow by a storm or other energetic fluid environment and then the stuff settled and mineralized.

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Indy

it isn't a direct analogy but i've got some fossil plant material from younger strata that is similarly "jumbled". i've also seen a fascinating jasp-agate with the equivalent of a plant breccia sort of look to it. i just sort of wonder if the environment couldn't have caused the cellulose to start breaking down and coming apart and the material got agitated somehow by a storm or other energetic fluid environment and then the stuff settled and mineralized.

I agree... B)

High energy lagoonal environment could easily play a major role in the appearance.

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ashcraft

Unless there is something there that I am not seeing, I am still going with stromatolite, using Occam's razor-

It was found in an oceanic deposition (I think)

It is from a time when land plant fossils were not particularly common

The deposit is known to have algal fossil remains

As I look at the photos again, it looks like a laminar stromatolite that might have been broken up and re-deposited.

Brent Ashcraft

Edited by ashcraft

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Maniraptoran

cool find, but has anyone ruled this thing out as a mineral?

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TqB

They look very much like root tufts of hexactinellid sponges.

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tracer

They look very much like root tufts of hexactinellid sponges.

looking at it again, i like your concept better than mine but couldn't find much in the way of comparative images to look at. got any links?

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Indy

I don't see sponge root tufts :blink:

post-6417-0-71178200-1319458173_thumb.jpg

Titusvillia? root tufts

Web page: My link

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TqB

Shamalama's last close-up pic looks right for hexactinellid. There doesn't seem to be much in the way of images on the web - here's a piece of "Hyalostelia" (a bit of a catchall genus) from the Carboniferous.

Scale=1cm

post-4556-0-68650400-1319459230_thumb.jpg

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piranha

TqB's suggestion of a sponge root tuft sounds promising. A hexactinellid even better except there are none described in the Treatise from the Silurian of Pennsylvania. Attached are examples of Stiodermatidae (Uralonema-Carbiniferous) and Dictyospongiidae (Hyalosinica-Cambrian) each within Hexactinellida that exhibit similar overall morphology and described having a stalk and root tuft of coarse spicules with loosely twisted texture. Perhaps we can discover a list of the fossil sponges of Pennsylvania (Ordovician-Devonian) that can point in the right direction?

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post-4301-0-40259800-1319476726_thumb.jpg

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Shamalama

Oh interesting, Sponge "roots"? That is something different for sure.

Great ideas and pictures guys, I could see these being from a Hexactinellid sponge now.

I just ordered "Paleocommunities--a case study from the Silurian and Lower Devonian" from Amazon as it has a couple of papers that are referenced on the PaleoDB site for the Keyser formation. Hopefully it will have some more info on species found within.

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