4 large Florida fossil shells!

[Monica]

Hello all!

 

Last October, Ken @digit gifted me and Viola some large Florida fossil shells.  I took ownership of 4 shells and Viola took the rest.  Now that I'm almost done labeling all of my fossils, I would like to put a genus and perhaps even a species for each of my specimens - any and all help is much appreciated - perhaps @MikeR can provide some assistance?   And, Ken, are these from "Cookiecutter Creek"?  And what age should I put to them?

 

Specimen #1: A bivalve - perhaps Mercenaria sp.?

 

Specimen #2: Another bivalve - perhaps Dinocardium sp.?

 

Specimen #3: A gastropod with the opening on the left, so I think it might be Sinistrofulgur contrarium - is this correct?

 

Specimen #4: Another gastropod - perhaps Melongena corona?

 

Thanks in advance!

 

Monica

[digit]

Yup. All of those come from the shelly layer in Cookiecutter Creek. I'm presently picking through some fine micro-matrix from this locality and finding interesting mollusk shells though several of them turn out to be from land snails and are not marine at all. The shelly layer we believe is the early Pleistocene Caloosahatchee Formation. @MikeR is going to be your best resource on getting the correct names on these.

 

I believe #4 is likely to be Melongena subcoronata as I believe that's been correctly identified before from this site. The left-handed #3 looks correct to me. I think #2 might be Dinocardium robustum but there are likely multiple species so Mike would have to confirm. And completing the backwards review, I think #1 may be Mercenaria campechiensis (the Southern Quahog).

 

Fond memories of watching Viola unpack a bunch of Florida fossil shells (which survived the trip up to the Toronto area from Florida remarkably well).

 

 

Cheers.

 

-Ken

[Darktooth]

Nice shells Monica! I collected  some of these when I hunted with Ken, in March. I wish that I had taken some pics of the shell layer, as it really was an incredible sight. In the banks of the creek were the layer is exposed, there are thousands, upon thousands of shells jammed together. 

[grandpa]

Beautiful fossils.  I really like the gastropods, so ornate - and large.  A plate of escargo from these guys would be like having steaks on the plate.  How nice of digit to part with these.  Living in Fla. certainly has its benefits.

[Monica]

11 hours ago, digit said:

Yup. All of those come from the shelly layer in Cookiecutter Creek. I'm presently picking through some fine micro-matrix from this locality and finding interesting mollusk shells though several of them turn out to be from land snails and are not marine at all. The shelly layer we believe is the early Pleistocene Caloosahatchee Formation. @MikeR is going to be your best resource on getting the correct names on these.

 

I believe #4 is likely to be Melongena subcoronata as I believe that's been correctly identified before from this site. The left-handed #3 looks correct to me. I think #2 might be Dinocardium robustum but there are likely multiple species so Mike would have to confirm. And completing the backwards review, I think #1 may be Mercenaria campechiensis (the Southern Quahog).

 

Fond memories of watching Viola unpack a bunch of Florida fossil shells (which survived the trip up to the Toronto area from Florida remarkably well).

 

 

Cheers.

 

-Ken

 

Thanks for all of this information, Ken!  Yes, Viola is still enamoured of all things "shell", so as soon as we organize her favourite fossils into a little display, I'll post a picture since I'm sure the stuff you brought her from Florida will be there!  That'll be a project for next summer since school begins today which means free time will decrease quite a bit until next summer...

(although now that I'm just about finished with my fossil display I feel ready to search through the "Cookiecutter matrix" you brought us - that will likely happen over Christmas - already looking forward to it!)

 

11 hours ago, Darktooth said:

Nice shells Monica! I collected  some of these when I hunted with Ken, in March. I wish that I had taken some pics of the shell layer, as it really was an incredible sight. In the banks of the creek were the layer is exposed, there are thousands, upon thousands of shells jammed together. 

 

Thanks, Dave!  I would love to see the shelly layer in person - it sounds amazing!!!  If I ever make it down to Florida I'll make sure to give Ken @digit a call 

 

6 hours ago, grandpa said:

Beautiful fossils.  I really like the gastropods, so ornate - and large.  A plate of escargo from these guys would be like having steaks on the plate.  How nice of digit to part with these.  Living in Fla. certainly has its benefits.

 

Thanks so much!  I'm not a fan of escargot but I really love their fossils! 

[MikeR]

In order:  Mercenaria tridacnoides, Dinocardium robustum, Sinistrofulgur contrarium, and Melongena subcoronata.

[digit]

8 minutes ago, MikeR said:

Mercenaria tridacnoides

Interesting! I see that tridacnoides was formerly listed as a subspecies: Mercenaria campechiensis tridacnoides. Has this been moved to full species status?

 

https://en.wikipedia.org/wiki/Mercenaria

http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_no=108718

 

I noticed that Monica's specimen has a bit of a "fault line" running perpendicular to the growth lines on the shell. Is this what distinguishes this (sub)species? I'm only hazarding this guess as I'm assuming "tridacnoides" means "resembling a tridacna" which is the very large fluted shell from the Indo-pacific. Would be great to add a wee bit of learning to this identification.

 

 

Cheers.

 

-Ken

[Monica]

20 hours ago, MikeR said:

In order:  Mercenaria tridacnoides, Dinocardium robustum, Sinistrofulgur contrarium, and Melongena subcoronata.

 

Thanks so much, Mike!

[digit]

Isn't it great to have such a diverse brain trust here on TFF?

 

 

Cheers.

 

-Ken

[Monica]

4 hours ago, digit said:

Isn't it great to have such a diverse brain trust here on TFF?

 

 

Cheers.

 

-Ken

 

Indeed!

[MikeR]

Ken et. al.

 

I was on a business trip and going from memory, I listed the Quahog as Mercenaria tridacnoides when it should have been M. corrugata.  The large Mercenaria from the Pliocene of SE USA are quite variable, can be difficult to identify, and there have been a number of named species, subspecies and interpretations.  I looked at the fossilworks reference by Hendry et. al. and it appears that the species and interpretations were uploaded directly for future publications.  They dropped the subspecies tradacnoides from M. campechiensis probably because a subspecies is nothing more than a species variant.  I believe it was Gardner (1943) that first re-described the different species of Pliocene Mercenaria as subspecies of extant M. campechiensis.  When compared to each other the different Mercenaria look quite different, however intergrades exist.  If they are indeed subspecies, I believe that Campbell (1994) is more accurate with M. campchiensis campechiensis, M. campechiensis permagna and M. corrugata, M. corrugata tridacnoides.  In his descriptions he notes that multivariate analysis could sort this out.  So based on Campbell I would call the shell above Mercenaria corrugata.

 

   

From left to right:  Mercenaria campechiensis (Gmelin, 1791) Upper Pleistocene Flanner Beach Formation, Pamlico County, North Carolina; Mercenaria permagna (Conrad, 1838) Lower Pleistocene Waccamaw Formation, Columbus County, North Carolina; Mercenaria corrugata (Lamark, 1818) Upper Pliocene Tamiami Formation, Sarasota County, Florida; Mercenaria tridacnoides (Lamarck, 1818), Upper Pliocene Duplin Formation, Bladen County, North Carolina.

[digit]

Always great to add some quahog knowledge. Thanks.

 

I'll have to pay attention to the large Mercenarias that I see at Cookiecutter Creek. I don't know if more than one species would be expected in the Caloosahatchee Formation that we believe is exposed in the banks of Cookiecutter Creek (may be making a field trip there this year with Roger Portell from the FLMNH to analyze the formation in more detail). My naive reading of the examples pictured above would seem to indicate that M. campechiensis and M. permagna may possibly be distinguished by ridge texture and overall profile shape. I'm guessing that the single (valley) line running perpendicular to the growth rings may be what distinguishes M. corrugata from M. campechiensis and that multiple flutings are the mark of M. tridacnoides (which would make sense to anybody who has seen a giant tridacna clam). Does my simplistic read of these above images have any merit? @MikeR

 

 

Cheers.

 

-Ken

[MikeR]

14 hours ago, digit said:

I'll have to pay attention to the large Mercenarias that I see at Cookiecutter Creek. I don't know if more than one species would be expected in the Caloosahatchee Formation that we believe is exposed in the banks of Cookiecutter Creek (may be making a field trip there this year with Roger Portell from the FLMNH to analyze the formation in more detail). My naive reading of the examples pictured above would seem to indicate that M. campechiensis and M. permagna may possibly be distinguished by ridge texture and overall profile shape. I'm guessing that the single (valley) line running perpendicular to the growth rings may be what distinguishes M. corrugata from M. campechiensis and that multiple flutings are the mark of M. tridacnoides (which would make sense to anybody who has seen a giant tridacna clam). Does my simplistic read of these above images have any merit? @MikeR

 

Hi Ken

 

It is not apparent in the pictures due to the angle in which I photographed the shells but M. permagna is oval, longer than high compared to M. campechiensis which is pretty much equal in height and width.  Campbell states that M. tridacnoides is so variable that it might be just an extreme variant of M. corrugata or M. campechiensis.  M. corrugata was abundant in Bed 10 Tamiami at both SMR and APAC and all that I have found have that single plication whereas Zone 2 Yorktown in Virginia and the Duplin in North Carolina have the thick wavy M. tridacnoides.  When looking at them side by side it is not hard to think of them as separate species however a study would be needed to say one way or the other.

 

A brief look at the FLMNH IP database shows that M. corrugata and tridacnoides were Pliocene whereas M. permagna was Lower Pleistocene which suggests the shell bed at Cookiecutter Creek is Tamiami.

 

Mike

[digit]

40 minutes ago, MikeR said:

plication

Thanks. That was the word I was struggling for.

 

Thanks again for the great nugget of information on Mercenaria.

 

 

Cheers.

 

-Ken

[Monica]

21 hours ago, MikeR said:

A brief look at the FLMNH IP database shows that M. corrugata and tridacnoides were Pliocene whereas M. permagna was Lower Pleistocene which suggests the shell bed at Cookiecutter Creek is Tamiami.

 

Great stuff, Mike!  So I'll go ahead and change the formation and age information on the labels to Tamiami for the formation and Pliocene for age.

 

@digit - when I eventually search through the "Cookiecutter Creek" matrix that you gave me and find specimens in it, would I label those in the same way as the shells above (i.e. Tamiami Formation, Pliocene)?

 

Thanks so much to both of you!!!!!!!!!!