Potomac River fossil

[NovaRunner]

I found this in Charles County, Maryland along the Potomac River along with the typical ray plates and shark's teeth. Any thoughts?

[Fossildude19]

I think this is a metamorphic rock, not bone.

[NovaRunner]

That was one of the possibilities discussed among the people on the beach today, as was petrified wood. It is difficult to see without a hand lens, but some of the striations are tubes that end in pore-like openings giving the appearance of biological structure. My background is in botany, but not the paleocene, so a few people suggested asking here.

[Rockwood]

I'd call this wood, over metamorphic rock, but I'm not at all positive that it is wood. 

[MarcoSr]

Maybe a wood cast, but I'm not seeing any cell structure or typical wood features when I blow up the pictures (somewhat blurry).  So I'm in the rock camp.  I would need to see magnified closeup pictures for a better ID.

 

Marco Sr.

[NovaRunner]

I don't see typical palm or other angiosperm wood structure either, but I definitely see longitudinal vessel or tracheid-like elements, and what appears to be a central, fibrous core. I am leaning toward root, but not being familiar with Paleocene flora, it's difficult for me to feel confident about it. I also have a botanical bias, hence the posting here where people seem to be more familiar with faunal remains. I've sent photos to a paleobotanist friend and will see what she thinks. Hopefully she won't want to subject it to a rock saw.

Edited April 7 by NovaRunner

[MarcoSr]

21 hours ago, NovaRunner said:

I definitely see longitudinal vessel or tracheid-like elements, and what appears to be a central, fibrous core.

 

In the posted pictures or in person?  If in the posted pictures, please point out.

 

Marco Sr,

[Rockwood]

22 hours ago, NovaRunner said:

Hopefully she won't want to subject it to a rock saw.

Would you be good with a polished facet or two?

[NovaRunner]

1 hour ago, MarcoSr said:

 

In the posted pictures or in person?  If in the posted pictures, please point out.

 

Marco Sr,

Both, however, this photo may show it more clearly. The camera doesn't seem to like how the whitish material scatters light, but this angle casts enough shadow, I think.

[MarcoSr]

1 hour ago, NovaRunner said:

Both, however, this photo may show it more clearly. The camera doesn't seem to like how the whitish material scatters light, but this angle casts enough shadow, I think.

 

Thank you for the picture.  I can definitely see in this picture what you are calling longitudinal vessel or tracheid-like elements.  The visible vugs add more credence to me that they could be longitudinal vessel or tracheid-like elements.  I don't see petrified wood/fern rip cuts (I don't have any rip cut pieces in my collection), so I don't get to see longitudinal vessel or longitudinal tracheid-like elements.  The below pictures are what I typically see of them in cross-section.  I'm going to ask TFF member @ynot if the features shown in your picture could be purely geologic.

 

 

 

 

 

 

Marco Sr.

[ynot]

I see slickensides on a quartz vein, not any biologic.

[NovaRunner]

Because academics tend to ponder things at the speed of molasses, it took a couple of weeks for me to get any response about this specimen, and I subsequently forgot to post about it. Everyone was significantly less excited about it than I was, and general consensus is, yes, it could be a root, but it does not have any characteristics that are particularly diagnostic, so it would go into the pile with all the other petrified wood. It will live on my desk with all my other found treasures.