Miocene Unknown from Maryland Shore

[eccodave1]

Need help with ID

[Vieira]

I'm with some difficult in see the details of the fossil...

 

But looks like some type of Bivalve.

 

If you can, put some more pictures. Wait for other comments.

[eccodave1]

I would agree but I don't see where a pivot  or opening would be. The crack on one side does not appear to be an opening???

[FossilDAWG]

It loos like a large bivalve to me also, something like a mussel along the lines of Perna or possibly a Pinna (horse mussel) like form.  The "crack" is likely the hinge line.  You don't show the side views so we can't tell if there is an opening between the valves on the side opposite the hinge.  It may be an internal mold (steinkern) which could make the contact between the valves more subtle.

 

Also it is important to give us an idea of the geological formation, age, and approximate locality where the specimen was found.  

 

Don

[eccodave1]

I will post a side view shortly.

This specimen came from a 3'X2' block of rock containing many bivalve fossils. The location is the Eastern Shore of Maryland which, once had a shallow sea during the Miocene Epoch as reported to me. The shoreline is tidal dependent, these large blocks of rock containing fossils are available only during very low tide. The land is made of sand and clay. 

 

An interesting note about how I was able to dislodge this specimen from the rock. Apparently this block was high enough in the water line to be subjected to a freeze/thaw cycling which made it possible to just pull the rock apart. Other blocks of rock nearby I could barely chip them with my hammer. So I might recommend if one has a block of fossils get them wet and put them in the freezer ...lol... course the wife might have a problem with this solution.   

[Fossildude19]

By eastern shore of Maryland, do you mean the Atlantic facing shore, or the Bay facing shore?

[eccodave1]

This fossil formation is located inland from the Chesapeake bay on a tidal river off of Eastern bay near St Michaels Md. Approx. 15 miles from the Chesapeake bay. It looks as though there is uplift in certain areas of the land and where this land is on water the erosion reviles the fossils. To clarify where these fossil are found is bet. the Chesapeake bay and the Atlantic ocean.

 

Hope this helps.

[Plax]

The book "Miocene of Maryland" I think by W. Bullock Clarke has excellent plates. Got mine from the Maryland Geological Survey 40 years ago and it is probably available as a pdf on line. I often wanted to check out the low exposures along the Choptank but never got around to it when we lived up North. There are several sites on the eastern shore mentioned in the publication. Here's a link I found:

https://books.google.com/books?id=drQ9AQAAMAAJ&pg=PR58&source=gbs_selected_pages&cad=2#v=onepage&q&f=false

  Looks like you have a steinkern of Melina or Atrina. the modern name is different though I think.

[FossilDAWG]

I bought a CD/ROM version from the Maryland Geological Survey several years ago.  I really like the plates! They must have been an enormous amount of work to produce, but the figures are so much clearer than photos usually are.

 

Don

[eccodave1]

Thank you so much for your help FossilDAWG, I feel like a student studying for an exam so my brain hurts...I will look for the CD, I have goggled Md. Fossils and have tons of sites to look at. Also, Amazon came up in my searching. I have also started looking into W. Bullock Clarke, what a library of info. It will take me sometime to get a handle on this.

 

Thanks again!! David

[Boesse]

It sort of strikes me as being a bit too robust to be Pinna (at least judging from modern specimens) but I definitely think some bivalve in that family is on the right track.

[eccodave1]

Looking at the tape measure in photos it is approx. 11" length and 8" width 3" thick at its thickest. I am somewhat hesitant to start to explore the "top" end to see how it terminates until I read more. Very heavy, using a bathroom scale 4.7 lbs. There are striations running length wise which are interesting but I do not know if that has meaning.

 

Thank You all for the help, I am of course new to this field. Any recommendations to a good magnifying glass or eye piece to use in the field---preferably hands free??