What is this fossil?

[Fossil Newbie]

Found this fossil at Rockford, Iowa, last week with a student group, and it didn't show up on our identification sheets. It's about the size of a quarter. Can anyone tell us what it is? Thank you.

[tmaier]

Well, that's pretty cool looking. I think it is a spiriferid brachiopod, but I've never seen one like that. Could this be an internal cast?

http://www.google.com/search?q=spiriferid+brachiopod+Iowa&btnG=Search&hl=en&gbv=1&tbm=isch

[Raggedy Man]

Did you find this at the fossil park? Is the sheet below the one they gave you? 

 

fossils.pdf

 

Although not on the sheet,  it best resembles Strophonelloides. It appears the majority of the outer shell has broken off. The sheet they give you is more of a simple reference guide.

[Fossil Newbie]

Yes, Raggedy Man, that is the basic sheet we were working from. At home, though, we've been scouring images on the Internet and can't find anything that looks like it. It's the small side of a brachiopod? (And thanks to both you and Chief Comedian for the suggestions. It's good to have some direction in our search.)

 

[Monica]

5 minutes ago, Fossil Newbie said:

Yes, Raggedy Man, that is the basic sheet we were working from. At home, though, we've been scouring images on the Internet and can't find anything that looks like it. It's the small side of a brachiopod? (And thanks to both you and Chief Comedian for the suggestions. It's good to have some direction in our search.)

 

Hi Fossil Newbie!

 

I think you do have both valves on your brachiopod - the smaller side is called the brachial valve and the larger side is the pedicle valve.  I've circled in red the part of your specimen that I think would contain the pedicle opening if the matrix was removed, so I think the valve containing the part that's circled in red would be the pedicle valve:

 

 

For a bit of brachiopod morphology, see image below - it's from http://www.geo.arizona.edu/geo3xx/geo308/FoldersOnServer/2003/4brachiopds.htm:

 

 

Did your student group find a lot of cool things?

 

Thanks for sharing!

 

Monica

 

[Fossil Newbie]

Thanks for the information, Monica! We'll look into it.
 And yes, the students found lots of fossils, although probably nothing unusual. I was along as a parent chaperone, so I'm in no way an authority!

[Scott S.]

Hi There,

 

It's been a long time since I've been on here, and I see this is a pretty old post but brachiopods are kinda my thing. Both valves are indeed present and the specimen is Strophonelloides reversa.(Harper & Boucot. 1978). It is a strophomenid brachiopod.

 

Cheers!