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Robski

Cretaceous Palm Frond?

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Robski

Found this in a river canyon in Northeastern B.C. that cuts through Cretaceaous sediments. It is out of a large broken ironstone nodule (120lbs) polished by the river gravels.  Actually, the river gravels are dominated by ironstone weathering out of the soft sediments.  Appears to be folded in on itself but the other side is hidden by the ironstone matrix.

 

It looks to be a Palm frond of some type but I am not sure.  What puzzles me is that it looks like a single crenulated leaf. There are a fair number of fossil plant bits around at this location and I did find another piece of one of these upriver.

 

Any help would be appreciated.

 

Best Regards

Rob

IMG_3587.jpg

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ClearLake

My first thought is a piece of an Inoceramus clam which were quite common in the Cretaceous.  And yes, they could be very large.  Here is an example right out of Wikipedia:

1280px-Inoceramus_cuvieri_Palaeontological_exhibition_Prague.jpg

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I_gotta_rock

I'm a mollusk person myself. I'm not so good with paleobotany, but it does not look like a shellfish to me. Looks much more like veins coming from a central rib. If you've found other leaves in the area, you're probably right that this is a large leaf. Maybe @Fossildude19, @oilshale or @paleoflor have some ideas?

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Norki
2 hours ago, ClearLake said:

My first thought is a piece of an Inoceramus clam which were quite common in the Cretaceous.

Yeah, agreed, my first thought was also Inoceramus.

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Robski

I have found quite a few Inoceramus fossils in ironstone concretions in this area but nothing over 4-5 inches.  This is only a fragment and is over two feet long.

 

Regards

Rob

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Norki
27 minutes ago, Robski said:

I have found quite a few Inoceramus fossils in ironstone concretions in this area but nothing over 4-5 inches.  This is only a fragment and is over two feet long.

 

Regards

Rob

A two foot long fragment is definitely within the realm of possibility. These things got up to be about four feet long.

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jpc

I have seen my share of both Cret clams and Cret palm fronds.  This on is a clam internal mold.  The ridges are rounded like a roller coaster.  On a plam leaf they would be triangular.

 

edit: I wrote this a few days ago and never hit send

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Robski

Fair Enough

 

That is one BIG Clam. 

 

Thank You Everyone!!

 

Rob

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DPS Ammonite
14 hours ago, Robski said:

Look for calcite prisms normal to clam surface that indicate that this is the original calcite shell. Better close up photos might reveal the prisms. Also, test shell with HCl acid to see if it fizzes. Calcite shell will fizz.

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Robski

Hello

No there are no calcite prisms or remnant prism structures visible in the ironstone.  Likely a cast.  Although I also find big ammonites in these ironstone concretions and sometimes none of the original shell is present after they are replaced / mineralized.  Sometimes there is some remnant calcareous shell but 90% of the time there is not.  I don't know if that applies here. 

 

I agree it is probably a cast.

 

Appreciate your Help.

Thanks

Rob

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Robski

Under magnification I do see some small remnants of shell under the fossil.  There is definitely a third dimension to it. 

 

Here are a couple river-worn Ammonites from upriver that are totally replaced by the ironstone within the concretions.  The remaining ironstone matrix is firmly attached to the fossils. 

 

Best Regards

Rob

IMG_3600.jpg

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Johannes

Inoceramus was my first thought, too, but second I would also mention tracefossils like Dictyodora, Zoophycos or Phycodes.

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