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Vermont fossil... or not?


bthemoose

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My wife and I spotted the large rock below yesterday along the shore of Lake Champlain in Shelburne, Vermont, and were intrigued by the light colored branching patterns. The rocks here are Ordivician in age. We're not sure whether these are fossils or not, but hopefully someone here can help. The pattern is flat/flush against the surface of the rock. Thanks in advance for your input!

 

872017097_Coral2.thumb.jpg.32d5b083a9a100c353069d299256dca1.jpg 

 

2113875202_Coral3.thumb.jpg.6e7cf739b002889cc7c235e57835a21f.jpg

 

1239309407_Coral1.thumb.jpg.f08d4f620237fe52c3b5b903cb13c542.jpg

 

 

 

 

 

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Branching bryozoans, I would think.

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    Tim    VETERAN SHALE SPLITTER

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It looks like a tracefossil, Chondrites.

p1560956achondrites13clogher.thumb.jpg.5ca511a144e53c0c8c47aded281ecf1e.jpg

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All we have to go on is the gross morphology, but I'm convinced that this is not a bryozoan colony. The taper and fracture pattern is wrong.

Notice how in a few spots one feature cuts through an existing one. More likely seen in burrowing I believe.

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7 minutes ago, Rockwood said:

All we have to go on is the gross morphology, but I'm convinced that this is not a bryozoan colony. The taper and fracture pattern is wrong.

Notice how in a few spots one feature cuts through an existing one. More likely seen in burrowing I believe.

 

My only misgiving with the ichnological explanation is the differing color between the items and surrounding matrix.

Usually, the colors are homogeneous and  uniform.  :unsure:

    Tim    VETERAN SHALE SPLITTER

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51 minutes ago, Fossildude19 said:

 

My only misgiving with the ichnological explanation is the differing color between the items and surrounding matrix.

Usually, the colors are homogeneous and  uniform.  :unsure:

I agree, but there are exeptions. :)

 

1-s2.0-S0012825219300662-gr2.jpg.303e8f7dd51547113bade45ece0070cc.jpg

Baucon et al., 2019

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1 hour ago, Fossildude19 said:

Usually, the colors are homogeneous and  uniform.

Not in a coral reef environment. All the available carbonate, ya know. 

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14 minutes ago, Rockwood said:

Not in a coral reef environment. All the available carbonate, ya know. 

Not so. There are a number of reefal environments here in my early mid-Devonian strata where they are indeed homogeneous in colour (and particularly so in bituminous layers). Both types (hetero-/homogeneous colouration) can present depending on a number of taphonomic factors.

...How to Philosophize with a Hammer

 

 

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1 hour ago, Kane said:

Not so.

Ya so. The argument was that in a coral reef environment they are not always homogeneous. As you just confirmed.

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I see branching. Would a creature back up (beep, beep, beep) to try another direction or just keep moving forward?

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

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42 minutes ago, Rockwood said:

Ya so. The argument was that in a coral reef environment they are not always homogeneous. As you just confirmed.

Tim stated they are usually homogeneous. You said no. I confirmed they can be, and that both types present. As you stated: "Not in a coral reef environment," suggestive of an exclusive disjunction. 

...How to Philosophize with a Hammer

 

 

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15 minutes ago, Kane said:

suggestive of an exclusive disjunction.

Then you're saying that in a coral reef, such as the post likely is, trace fossils are usually homogenous ?

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18 minutes ago, Rockwood said:

Then you're saying that in a coral reef, such as the post likely is, trace fossils are usually homogenous ?

 

No, he is saying they can be either.  Just like you are.

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    Tim    VETERAN SHALE SPLITTER

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1 hour ago, Mark Kmiecik said:

I see branching. Would a creature back up (beep, beep, beep) to try another direction or just keep moving forward?

 

"The bedding plane expression of Chondrites is well-constrained by morphometry: (1) the angle of dichotomy formed by a pair of adjacent branches is typically between 30° and 56° (interquartile range; mean: 47°); (2) branching order is between 1 and 9; (3) branches are, on average, nine times longer than wide. In the third dimension, downward branching is dominant but bundled shafts and upward branching may be present." (...)

"The tracemakers built Chondrites to obtain food: (1) vermiform deposit feeders produced Chondrites for searching for food in the sediment (fodinichnion); (2) asymbiotic bivalves built Chondrites for cultivating and directly ingesting bacteria (agrichnion); (3) chemosymbiotic bivalves produced Chondrites to provide symbionts with chemical agents. Chondrites was modified through the life of the tracemaker or it represented a part of the producer’s lifespan." - Baucon et al., 2019

Why-did-an-organism-produce-Chondrites-768x538.jpg.aff832411d61b06c5a4a22df53bae245.jpg

Edited by abyssunder
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" We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. "

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1 hour ago, Mark Kmiecik said:

I see branching. Would a creature back up (beep, beep, beep) to try another direction or just keep moving forward?

One crucial aspect here is that traces are not assigned to a single creature. They are rather structurally defined. 

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1 hour ago, Rockwood said:

One crucial aspect here is that traces are not assigned to a single creature. They are rather structurally defined. 

 

My feeble mind failed to consider the possibility of more than one architect. My bad.

Edited by Mark Kmiecik
fix typo

 

 

Mark.

 

Fossil hunting is easy -- they don't run away when you shoot at them!

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Quite interesting, I took it for granted that this is some sort of "body fossils"

However, inspecting the rather good pic closely, it seems, that the texture of the dark matrix and the bright branches is the same - ??

@bthemoose, what to you see/think, is there only a color difference between matrix and branches or also some textural difference (grain size etc.?)

How does the specimen look like in side view? Is the pattern restricted to one bedding plane?
Franz Bernhard

 

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47 minutes ago, FranzBernhard said:

Quite interesting, I took it for granted that this is some sort of "body fossils"

However, inspecting the rather good pic closely, it seems, that the texture of the dark matrix and the bright branches is the same - ??

@bthemoose, what to you see/think, is there only a color difference between matrix and branches or also some textural difference (grain size etc.?)

How does the specimen look like in side view? Is the pattern restricted to one bedding plane?
Franz Bernhard

 

 

The rock isn't in my possession so I can't inspect it further unfortunately. I'm not sure that collecting from this property is permitted (it's a privately owned, non-profit property that's open to the public) but this would have been far too large to carry home in any case.

 

If I get back out to this spot on this trip I can try to take more photos and examine more closely. From memory, I believe that color was the main differentiator and I don't recall any textural differences. I don't think that I looked at the piece from the side.

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Not an expert -- there aren't any Ordovician beds within six hours of me, except possibly in the subsurface -- but my thought was trace fossils also.

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12 hours ago, Ludwigia said:

Here is a link to a Chondrites in my collection for visual comparison.

That's a very nice specimen, Roger! :)

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" We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. "

Thomas Mann

My Library

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