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Fossil ID - help with shell fossil


teatree

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Hi, I would really like some help to ID this fossil shell. Is it a brachiopod ?

What time would this be from?

I found this in the quicksilver almaden county park in California. There were quite a few similar shell fossils, Parts of them are visible in this piece of rock itself.

Thanks a lot !

IMG_2487.jpg

IMG_2492.jpg

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Looks like a bivalve to me. One of the scallops, a pectinid. 

Nice. :)

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Tortoise Friend.

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Yes I agree with Tidgy's Dad.   Oldest rocks are Jurassic and upper Cretaceous in Almaden County

 

 

 

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Thanks a lot Tidgy's Dad and Creek - Don ! 

I'm a newbie and would really appreciate if you share your reasoning a little bit. 

I'm confused how to distinguish between a bivalve and brachipod .

This fossil seems to not be symmetrical across the beak (I'm not sure if I used the right terms). Is that what makes it a bivalve ?

Thanks for taking the time to answer my questions !

Thanks

Edited by teatree
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An illustration from the Kansas Geological Survey (although the pectinids present a bit of a challenge!)

 

Fig4.jpg?zoom=2

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...How to Philosophize with a Hammer

 

 

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23 minutes ago, teatree said:

Thanks a lot Tidgy's Dad and Creek - Don ! 

I'm a newbie and would really appreciate if you share your reasoning a little bit. 

I'm confused how to distinguish between a bivalve and brachipod .

This fossil seems to not be symmetrical across the beak (I'm not sure if I used the right terms). Is that what makes it a bivalve ?

Thanks for taking the time to answer my questions !

Thanks

As Kane says, some of the pectenids' valves do look pretty much bilaterally symmetrical and the individual valves can be one flat and one convex; there is always an exception to test the rule. Internally, of course, they are very different to brachiopods, but we can't see the muscle scars or articulation on these specimens, so it's sometimes simply a case of knowing the age of the sediments, the types of fossils that occur in the area and experience. 

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Life's Good!

Tortoise Friend.

MOTM.png.61350469b02f439fd4d5d77c2c69da85.png.a47e14d65deb3f8b242019b3a81d8160-1.png.60b8b8c07f6fa194511f8b7cfb7cc190.png

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