Endocast or original

[Shellseeker]

A week or so back I posted a few shells I had found in a shell pile above Arcadia Florida. In the intervening time, Hurricane Irma chased me from Sanibel to Ormond on the Atlantic Ocean.  I drove back today, constantly looking for gas and coming down Route 17 which was hard hit by the hurricane (washed out roads, trees, power lines, telephone lines down).

I paused at one of my favorite Peace River launch sites: Heard Bridge.  For anyone who has been there , these two photos are almost unbelievable.  It is normally 30 feet between the bottom of the bridge to the river;  The parking area normally handles 15 cars, is completely inundated.

 

Because I am an addicted fossil hound,  I stopped at the shell pile in Arcadia. These last few photos.. Is this the seashell or an endocast?  In either case, please help ID the shell.

[GeschWhat]

I am useless when it comes to shells, but wanted to say that I hope you didn't suffer any losses due to Irma.  My thoughts and prayers are with all of you down there. Stay safe!

[DPS Ammonite]

The last few photos show the internal mold (hardened sediment that filled the shell) of a gastropod with traces of the original shell that has mostly dissolved or crumbled away. Your photos do not show an endocast which is a specific term of art that refers to the sediment filling the interior of a vertebrate braincase. An endocast is an interior mold of the braincase. The photo below shows part of the spiral original shell.

 

[Rockwood]

Unless someone was around to apply mold release I think there must be some of the inner shell left. 

[Sacha]

Jack, glad you're safe. Love the pictures of Heard Bridge. Hope that stiffens up the parking lot a little instead of washing it away!

[Shellseeker]

11 hours ago, DPS Ammonite said:

The last few photos show the internal mold (hardened sediment that filled the shell) of a gastropod with traces of the original shell that has mostly dissolved or crumbled away. Your photos do not show an endocast which is a specific term of art that refers to the sediment filling the interior of a vertebrate braincase. An endocast is an interior mold of the braincase. The photo below shows part of the spiral original shell.

 

Agreed, but I believe that common nomenclature has adopted the original meaning to include an internal mold of fossil seashells:  This from Wikipedia on the meaning of "Fossil" -- not scientific but within the language.

Quote

Casts and molds

External mold of a bivalve from the Logan Formation, Lower Carboniferous, Ohio

In some cases the original remains of the organism completely dissolve or are otherwise destroyed. The remaining organism-shaped hole in the rock is called an external mold. If this hole is later filled with other minerals, it is a cast. An endocast or internal mold is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail or the hollow of a skull.

 

6 hours ago, Rockwood said:

Unless someone was around to apply mold release I think there must be some of the inner shell left. 

Depends on the process. I find many of these seashell molds in the peace river. The shell fills with sand/mud, the calcium carbonate in the shell dissolves over time, leaving a mold. Those molds have none of the original shell.

In this case ,part of the original shell remains, so some other process was/is going on.

 

Thanks for checking, Sacha and Geschwhat.  Lots of people are suffering but I just had to deal with no power and lots of trees down -- minor considering the issues of no power , water, ice, in severely hot conditions.

[Pilobolus]

was this a Calusa site?

[Rockwood]

2 hours ago, Shellseeker said:

Depends on the process. I find many of these seashell molds in the peace river. The shell fills with sand/mud, the calcium carbonate in the shell dissolves over time, leaving a mold. Those molds have none of the original shell.

In this case ,part of the original shell remains, so some other process was/is going on.

I think it's more a matter of degree to which the process has gone on. More, and you get replacement of the shell. Same you get steinkerns, and less you get shell.

[Shellseeker]

In searching the net, I found this fossil shell on pinerest. and naturally no identification of the seashell, which was found in St Lucie, Florida.  Maybe @MikeR can help ID. 

[Sacha]

2 hours ago, Shellseeker said:

In searching the net, I found this fossil shell on pinerest. and naturally no identification of the seashell, which was found in St Lucie, Florida.  Maybe @MikeR can help ID. 

 

Taat looks more like a Ruck's pit find than from St. Lucie county.

[Shellseeker]

4 hours ago, Pilobolus said:

was this a Calusa site?

I went back and sorted the shells.  About 80% of Gastropods and all 5 of the bivalves( doubles) I could find on the SW Florida beaches today.  The rest - a couple of corals and 6 or 7 gastropods do not exist currently.  See photos below... So relatively recent - Calooshatchee Formation, South Florida. That is what is strange about the one I would like identified -- it seems out of place.

56 minutes ago, Sacha said:

 

Taat looks more like a Ruck's pit find than from St. Lucie county.

Agree, John.  Calcite crystals -- should be Ruck's pit, but the site and the photo are IDed as St Lucie country. Do you think we could find a source there?  May be worth a trip!!!!!

[LordTrilobite]

3 hours ago, Shellseeker said:

In searching the net, I found this fossil shell on pinerest. and naturally no identification of the seashell, which was found in St Lucie, Florida.  Maybe @MikeR can help ID. 

That kinda looks delicious.

[Plantguy]

Hey Jack, Glad to hear your well. Irma was a test for all of us. Nice finds! I'm probably missing something...witch shell are you trying to ID? The lower right damaged specimen in the last photo? 

 

Rucks pit might be the best candidate for the St. Lucie gastropod calcite find but with the mineral rich waters that are in Florida those calcite fills/replacements do occur occasionally elsewhere. So far I've also picked up finds from the Suwanee Fm, Brooksville, Hernando Cnty, Tamiami Formation, Sarasota Cnty and Undiff beds in Manatee Cnty. 

 

Regards, Chris 

 

 

 

[jcbshark]

Wow Jack, heard rd is looking a little deep lol, glad you made out ok. Hopefully in a few months we ll all be enjoying a bit of river sifting

[Shellseeker]

15 hours ago, Plantguy said:

Hey Jack, Glad to hear your well. Irma was a test for all of us. Nice finds! I'm probably missing something...witch shell are you trying to ID? The lower right damaged specimen in the last photo? 

 

Rucks pit might be the best candidate for the St. Lucie gastropod calcite find but with the mineral rich waters that are in Florida those calcite fills/replacements do occur occasionally elsewhere. So far I've also picked up finds from the Suwanee Fm, Brooksville, Hernando Cnty, Tamiami Formation, Sarasota Cnty and Undiff beds in Manatee Cnty. 

 

Regards, Chris

This shell or mold seems older and out of place with the other shells I found around it.. In trying to identify the shell, I found this similar looking shell from Pinterest... Ruck's Pit is in Okeechobee county that borders St Lucie county , so real possible that a calcite replacement shell might be found there. Just passing time until we can get back in the river.

[Plantguy]

Hey Jack, that guy struck me as being similar to a number of Turbinella's that I have. Here's one showing the spire...may not be it and it will be interesting to see if Mike has a minute to chime in to offer some possibilities and a firm ID. . 

Here's the link the UF invertebrate gallery for that guy.. https://www.floridamuseum.ufl.edu/invertpaleo/display.asp?catalog_number=132121&gallery_type=Florida Mollusca-Gastropoda

 

I think the shell might not be displaced or different other than it provided a spot that was able to collect fill and have it cemented and minerals form. Here are the examples I have from other locales around the state. 99.9% of the invert material has no calcite infillings but they do show up once in awhile and are cool finds. Going to Rucks pit is still on my todo list...from what I've seen of that material and particularly their Mercenaria clams filled with large calcite crystals they are absolutely fascinating! 

Congrats!

 

Regards, Chris