Found on the shores of Lake Ontario

[TebanB]

My son found this on the shore of Presqu’ile Provincial Park.  Is this a fossilized sea snail? 

[Kane]

Indeed it is a steinkern of a gastropod. It looks like a match for Hormotoma trentonensis, and places it in the Ordovician. 

[Ludwigia]

Agreed, although I believe the species was revised and renamed Omospira trentonensis.

[Rockwood]

19 minutes ago, Kane said:

Indeed it is a steinkern of a gastropod. It looks like a match for Hormotoma trentonensis, and places it in the Ordovician. 

How does a steinkern do this much work? I thought it was pretty much you've seen one you've seen them all. 

[Kane]

In the Ordovician of Ontario, gastros are almost always steinkerns, so we differentiate them by shape.

[Rockwood]

38 minutes ago, Kane said:

In the Ordovician of Ontario, gastros are almost always steinkerns, so we differentiate them by shape.

Still seems a bit sketchy for a species designation to me. 

[Kane]

That's just the way it is. 

[Rockwood]

I guess it is common practice to name things even if only for the sake of reference.  

[Kane]

34 minutes ago, Rockwood said:

I guess it is common practice to name things even if only for the sake of reference.  

Barring a few miracles, such as finding more gastropods in our Ordovician deposits with shell material and/or a sudden flush of research funding, we may be stuck with what we have.  That said, it does seem a lot of our species differentiation based on shape (whorls, turret height, etc.) seems to work so far. As you say, a kind of reference point. 

[TebanB]

Thank you so much for all the information, both my 8 year old and I are astounded by the possible age of our find!