Ostracoderm Fragment?

[SilurianMan]

This is another specimen I would like to share from my long-ago collected specimen box.  It is my recollection that this was found while walking on exposed riverbed along the north shore of the 

St. Lawrence River somewhere near Quebec City.  The rib-like grooves as seen on the top view are what caught my eye, but after picking up and examining it more closely, the cross-section really got my attention.  This spoke "structural design" to me.   Although we've certainly all seen unusually shaped rocks that didn't mean anything, this, along with the grooves on the top side, it made me think it wasn't a random rock.

 

I'm guessing this is a fragment of an Ostracoderm, possibly Cephalaspis Lyelli(?).  Any other thoughts on what this might be?  Thanks in advance for your comments.

 

 

 

[Fossildude19]

I'm not seeing this as a Cephalaspis. Not seeing any real resemblance here.    

 

 

 

It may be something, but I am not positive. 

 

@jdp

[jdp]

Not seeing anything that would indicate a vertebrate fossil here.

[Misha]

Ostracoderms had bony head shields with some distinct surface detail.

This doesn't look like bone at all, it's just completely solid rock.

And here's what the surface detail on a cephalaspid fossil I have looks like:

 

I think that what you have is of geologic origin and not a fossil

[SilurianMan]

Thanks for the comments.  I agree that this doesn't match the head shield, but my thinking was that this could be a section posterior to the head shield.  See below.  It's heavily weathered so any surface detail could have eroded away.

 

[Misha]

This is definitely not the scales either, the scales on these fish would have been a lot thinner than what you have, and the rippling is not something you would see on them either.

 

I still stand by the idea that this is an object of geologic origin, I see nothing that would suggest a fossil of any kind.

[GeschWhat]

To illustrate the geological origin, notice the darker minerals running crosswise. I think you have some type of siltstone with the ridges resulting from erosion/weathering. I'm not seeing a fossil, sorry. 

[FossilDAWG]

We can also note that the bedrock in the vicinity of Quebec City is Cambrian and Ordovician, too old for the Devonian Cephalaspis.  Although isolated ostracoderm denticles have been recovered from acid residues of a few Ordovician limestones, these are microscopic and they are not known to occur in the Ordovician formations along the St. Lawrence River.

 

Don