Design On Brachiopod - Possible Coloration During Life?

[WyomingRocks!]

Hello, one of the Mississippian sites I collect from in Oklahoma preserves the brachiopods (Chonetes?) and other fossils very well. The one on the right shows a distinct pattern of spots and I have been wondering if this could be evidence of a color pattern that existed when it was alive. The shell on the left shows worm trails on the interior.

The shell on the right is 1 1/16" wide on hinge.

Edited March 6, 2013 by WyomingRocks!

[Bullsnake]

Good question, and wish I had an answer. I'll be keeping an eye on this thread for expert thoughts.

Great looking brachs!

[kwilson]

I'm not acquainted with with this species, but they look like they might be spine bases. I have seen similar patterns on some of our spiny brachs in the NY Middle Devonian such as Elita fimbriata.

[WyomingRocks!]

I'm not acquainted with with this species, but they look like they might be spine bases. I have seen similar patterns on some of our spiny brachs in the NY Middle Devonian such as Elita fimbriata.

They are not spine bases as this type only had the spines on the hinge line. The spots in question are perfectly smooth. Of course, being buried in the ground 300+M years ago could have changed things!

[Jurassic Jim]

collect a lot of chonetes around the Mississippian deposits here as well. Fascinated by the spotted one. I have never seen such a pattern on any I have collected. The fact that the spacing is so even leads me to believe it has to be related to the orginal shell material and not just a random artifact of the preservation. Whether it could be where coloration in life was would seem to be a possibility in my sure seems like a possibility in my opinion...something was different on those spots.

[Missourian]

It's also possible the microstructure of the shell material was somehow different in those spots, and were preserved that way due to particular conditions during fossilization.

Edited March 7, 2013 by Missourian

[erose]

I'm not acquainted with with this species, but they look like they might be spine bases. I have seen similar patterns on some of our spiny brachs in the NY Middle Devonian such as Elita fimbriata.

It's also possible the microstructure of the shell material was somehow different in those spots, and were preserved that way due to particular conditions during fossilization.

Some brachiopods had shells with holes through the surface. I believe they are called "punctate" and in one book these holes were speculated to be the pores through which poisons or other irritants might have been secreted. They occur in a a variety of brachiopods but can be just about mircoscopic and you almost need to do thin sections thru the shell to find them.

I suspect that those little spot are discoloration around those pores.

[Caleb]

Here's a link to a paper dealing with color patterns on Devonian brachiopods from the Ukraine. (It's a small PDF)

http://www.app.pan.pl/archive/published/app55/app20100066.pdf

[WyomingRocks!]

Hello, thanks for everyones replies. I took a picture of several of the Chonetes found at this site and they show the pattern as well. If this was caused by the tiny pores why are the spots so much larger? I am just speculating about these shells as I wanted to learn something.

Well, I just looked at the close-up of these pictures and on some of the spots you can see a small pit or hole. This may substantiate what erose said.

Stephen

Edited March 8, 2013 by WyomingRocks!