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Are these Graptolites?


Dsailor

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Hi Folks,

 

I found this rock and I think they are Graptolites but I am not sure. They were found in New York state but I do not know the formation or age since the rock was part of an erosion control  barrier in another site. Under magnification, some have a definite serrated edge.

 

Thanks for your help,

 

Dom

DSC_0540 - Copy.JPG

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That's a nice slab by the way.  Somebody will probably be along with a link to a paper or two on paleocurrents :)

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10 minutes ago, Peat Burns said:

Could they be, rather, Tentaculites ?

I have no idea, man, since I just had to google what "tentaculites were. They do look very similar. Thanks

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6 minutes ago, Dsailor said:

I have no idea, man, since I just had to google what "tentaculites were. They do look very similar. Thanks

I'm pretty sure they are Tentaculites.  I just exercise some extra caution regarding absolutes when identifying from photos and doing so on my small phone screen :)

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It seems not too much is known about them beside they may be related to brachiopods. They are cool little fossils though :)

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23 minutes ago, Dsailor said:

It seems not too much is known about them beside they may be related to brachiopods. They are cool little fossils though :)

I hadn't heard that.  Last I knew is they might be related to molluscs.  They are definitely very cool.  That's a great plate you have there.

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I agree- tentaculites. They are common in New York State, especially from the Manlius Formation which is the earliest Devonian. That's a pretty nice slab. I have some posted in my Lower Devonian gallery if you want to compare.

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Tentaculites sp., if it's Silurian I'd go with T. niagarensis, not sure what the Devonian species is. 

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2 minutes ago, EMP said:

Tentaculites sp., if it's Silurian I'd go with T. niagarensis, not sure what the Devonian species is. 

I know of a few cricoconarids from the Devonian (in my area, at least):

Tentaculites attenuatus (Hall)

Styliolina fissurella (Hall)

 

A close up of the image makes it more likely to be tentaculites sp. given the evidence of the growth rings (which the Styliolina do not possess). They look more like t. bellulus than t. attenuatus on account of the wider fluting (if they are Devonian).

 

Further reading (with some very good photo plates):

Hajlasz, Barbara. (1974). "Tentaculites of the Upper Silurian and Lower Devonian of Poland." Acta Palaeontologica Polonica. XIX.4 [LINK]

 

The author also published a second good resource in 1976, but I do not have a copy on hand:

Hajlasz, Barbara. (1976). "Tentaculites and their stratigraphic significance, the lower Devonian". Kwartalnik Geologiczny, 20, 273-288.

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...How to Philosophize with a Hammer

 

 

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