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Is this an ammonite?


killerdog

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It is "the Devil's Toenail" or more accurately Gryphaea arcuata, a type of ancient oyster  from the Lower Jurassic. 

Life's Good!

Tortoise Friend.

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

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Thank you very much.

Based on your knowledge, is it a good un?

Cuz it looks a bit beeter than the ones on ebay

but then I dont know what the good ones look like

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It is a little worn, but a pretty excellent specimen with both valves nicely preserved. :)

Better than any of mine! :(

Life's Good!

Tortoise Friend.

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

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Now youve told me what it is, Im trying to understand, on photo 3 the large flat peice is seperate and it lifts up and down for the thing inside? Is that correct?

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That's right. 

It's the second valve of the bivalve and is a protective 'door' or 'lid'. 

Life's Good!

Tortoise Friend.

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

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Devil's Toenail, Gryphea acuata.

 

Watch out, the big baddie may want his nail back, plus your soul! :P

 

Every single fossil you see is a miracle set in stone, and should be treated as such.

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10 minutes ago, Tidgy's Dad said:

That's right. 

It's the second valve of the bivalve and is a protective 'door' or 'lid'. 

thank you for all your information

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9 minutes ago, killerdog said:

thank you for all your information

Pleasure! :)

Especially when people say thank you. :)

Life's Good!

Tortoise Friend.

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4 minutes ago, killerdog said:

not gonna sell it but what is it worth?

Unfortunately, the Forum doesn't permit valuations, so looking on the auction sites is the best bet for a value.

Not something i know much about, anyway. :)

Life's Good!

Tortoise Friend.

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

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fair do. would you say this one is common?

just would like to know if I have a rare one?

 

Still happy with what I got, 200 millions years old!! Beautilul.

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The species is very common at many locations in the UK.

But it is more unusual to find one that well preserved, though maybe not 'rare'.

Life's Good!

Tortoise Friend.

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I agree with the ID. The smaller valve is considered the right valve and the larger is the left. At least I think I have that right. Oysters usually have the larger valve attached to something solid so only the right valve moves to pump the water through where most other bivalves move both valves apart and back together. I always wondered why oysters have such different sized valves compared to other bivalves and whether they laid down a new layer on the smaller one every time they added to the other valve. I suppose I could just count the growth lines to tell but the layers must be much thinner in the right valve.

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1 hour ago, BobWill said:

 "I always wondered why oysters have such different sized valves compared to other bivalves..."

Gravity. It is easier for an oyster to lift the small valve. Plus, the lower valve needs to be larger because it needs to grow fast, curve and push the oyster up from the substrate that is accumulating sediment so that the oyster does not smother. Imagine a Texigryphea ponderosa trying to lift its large valve up.

 

Killerdog, Gryphea acuata are very cool but very common.

 

My goal is to leave no stone or fossil unturned.   

See my Arizona Paleontology Guide    link  The best single resource for Arizona paleontology anywhere.       

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1 hour ago, DPS Ammonite said:

Gravity. It is easier for an oyster to lift the small valve. Plus, the lower valve needs to be larger because it needs to grow fast, curve and push the oyster up from the substrate that is accumulating sediment so that the oyster does not smother. Imagine a Texigryphea ponderosa trying to lift its large valve up.

 

Killerdog, Gryphea acuata are very cool but very common.

 

Thanks John, that makes sense. You would think that thin shell would make it easier for a gastropod to bore into the shell though. Maybe they don't like all that movement. Did you move to Arizona?

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