Fossil Geoduck?

[PFOOLEY]

I found this clam eroding from a concretion in the Carlile Shale (Turonian) outcrops which I hike regularly.

After much debate (with myself ) about the i.d. of this clam, I want to label it as panopea sp. (the modern species is referred to as a geoduck) but wanted to post it here to get your thoughts as well.

Is this a fossil geoduck?

Thanks for pondering,

-P.

[RichW9090]

I know the genus goes back to the Miocene, but I don't know if it goes as far back as the Late Cretaceous.

According to the data base, it goes back as far as the Triassic!

http://fossilworks.org/bridge.pl?taxon_no=18482&action=taxonInfo

Rich

Edited December 7, 2013 by RichW9090

[non-remanié]

I'd go with Panopea. Nice one. We get them in Campanian and Maastrichtian sediments here in NJ.

[RichW9090]

I note that the genus is not listed as having been found in New Mexico in the data base - you might want to take it in to the museum in Albuquerque for someone to look at and verify.

Edited December 7, 2013 by RichW9090

[MikeR]

Nice bivalve but not Panopea. Panopea has an extensive fossil record and I have found it as far back as the Coon Creek Formation (Maastrichtian). It is actually more uncommon to find as a single valve as it will burrow a meter or more in to the sediment where it will eventually die and preserve in living position. Valves are gapped at both ends as seen below. The anterior end is where the foot protrudes for movement and the posterior end from which the breathing/feeding siphon extends to the surface.

Panopea americana Conrad, 1838. Middle Miocene Choptank Formation. Calvert County, Maryland.

Recent Panopea with extended siphon

It could be related in the Subclass Anomalodesmata, but I not familiar enough with Turonian bivalves to be of much help.

Mike

Edited December 7, 2013 by MikeR

[RichW9090]

We can't actually see for sure if the shell is gapped at both ends from the photograph. Can we get a better view?

[PFOOLEY]

...and I have found it as far back as the Coon Creek Formation (Maastrichtian)...

Would you happen to have any photos the specimens?

[PFOOLEY]

This specimen is a single valve which eroded from a calcite nodule. These are the best views I can offer.

I did find that a species of panopea (p. webbi) was described from the Kaskapau Fm. (Smokey Grp.) of British Columbia.

PS Warren, 1933; New Coloradoan species from the Upper Peace River, B.C.

From the information I can find on this documentation, the outcrop is middle Turonian shale and has the ammonite zones of Collignoniceras Woollgari and Prionocyclus Hyatti... sounds very much like the area the specimen in question is from. ...Very cool nonetheless.

Thanks for your input.

Edited December 11, 2013 by PFOOLEY

[Uncle Siphuncle]

crack it open... could be a geo-tur-duc-hen

[RichW9090]

I agree with MikeR - it does not appear to have gapped openings at each end of the shell. Not a Panopea.

[Al Dente]

Here's a Panopea in life position in a Yorktown outcrop. It is below an Ecphora.

[PFOOLEY]

Thanks to all for your input. I will keep searching for a proper i.d.

[dozer operator]

Fossil geoduck from southeast florida mine

[Plax]

Cymella or Liopistha? Wish I had my books here at work.......

[PFOOLEY]

I recently found another specimen of this mystery bivalve...

 

 

 

...from the Upper Cretaceous (middle Turonian) Semilla Sandstone member of the Carlile Shale.

 

Does anyone recognize this genus? 

 

Thanks for your thoughts.