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JUAN EMMANUEL

Late Ordovician/Early Silurian Shark Scales?

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JUAN EMMANUEL

I was reading a book about fossil fishes and there was a chapter dedicated to sharks and their cousins. Apparently there were chondricthyan scales found in the Late Ordovician and Early Silurian rocks.

Since I hunt the Late Ordovician Georgian Bay formation in Toronto, Ontario and various Early Silurian formations in Hamilton, Ontario, what are the chances of me coming across these scales? Should I keep my eyes open and what should I look for? 

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ynot

Placoid scales are generally very small, less than 1 millimeter.

So some type of magnification is helpful in looking for them.

 

Maybe @MarcoSr can help with this.

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FossilDAWG

They are microscopic and generally they are conical or curved cones with strong ridges from the base to the tip.  If you google "placoid scales" you'll get some examples.  Often these are discovered in the residue after rocks have been processed for conodonts.  It would be very unusual to be able to see them in the matrix.  They have been found in Ordovician limestone on St. Joseph's Island, between Manitoulin Island and Sault St Marie.  I do not recall reading or hearing about them being found in the Georgian Bay Formation or in the overlying Silurian formations.  Of course it is a good idea to have a search image for them in case they do show up, especially if you are processing rocks for conodonts or scolecodonts.

 

Don

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MarcoSr
17 hours ago, ynot said:

Placoid scales are generally very small, less than 1 millimeter.

So some type of magnification is helpful in looking for them.

 

Maybe @MarcoSr can help with this.

 

Tony

 

I have never searched matrix from the Late Ordovician Georgian Bay formation in Toronto, Ontario (or any other Ordovician formation) or matrix from the Early Silurian formations in Hamilton, Ontario (I have only looked at a small amount of Silurian matrix from the Rochester Shale, Niagara Co., New York )  so I really can't add anything to this post.  I would go with what Don has said above.

 

Marco Sr. 

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ynot
52 minutes ago, MarcoSr said:

 

Tony

 

I have never searched matrix from the Late Ordovician Georgian Bay formation in Toronto, Ontario (or any other Ordovician formation) or matrix from the Early Silurian formations in Hamilton, Ontario (I have only looked at a small amount of Silurian matrix from the Rochester Shale, Niagara Co., New York )  so I really can't add anything to this post.  I would go with what Don has said above.

 

Marco Sr. 

Oh well, it was worth the try.

Thanks for replying to My query.

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