teatree Posted May 15, 2020 Share Posted May 15, 2020 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 ! Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted May 15, 2020 Share Posted May 15, 2020 Looks like a bivalve to me. One of the scallops, a pectinid. Nice. 2 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Creek - Don Posted May 15, 2020 Share Posted May 15, 2020 Yes I agree with Tidgy's Dad. Oldest rocks are Jurassic and upper Cretaceous in Almaden County 2 Link to comment Share on other sites More sharing options...
teatree Posted May 15, 2020 Author Share Posted May 15, 2020 (edited) 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 May 15, 2020 by teatree 1 Link to comment Share on other sites More sharing options...
Kane Posted May 15, 2020 Share Posted May 15, 2020 An illustration from the Kansas Geological Survey (although the pectinids present a bit of a challenge!) 4 ...How to Philosophize with a Hammer Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted May 15, 2020 Share Posted May 15, 2020 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. 4 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
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