Brachiopod.....should I Leave It In Matrix?

[bluepickup]

I found this brachiopod a couple of weeks ago in the Pennsylvanian limestone near by. It's about 5/8" long and my first of this type. I'm still not sure of the ID yet.

It was nearly all encased in the matrix. So far I've got it out this much by tapping it gently and getting the limestone to fall away.

Should I try to get it all the way free or leave it as it is now?

Here's anther angle with a crinoid cross section in view.

Edited November 16, 2013 by bluepickup

[Ridgehiker]

Looks like -Composita ovata....a well known Upper Carboniferous brach. However, Composita is a bit of a 'catch all' genus for brachs of that age. They can vary quite a bit in their roundness. Also, labels are sometimes put on brachs even though the particular deposit hasn't been studied....then names are often revised later.

However, will defer on the ID to someone locally.

I collect brachs and personally prefer them in matrix as they are a better display piece. Sometimes I'll cut the base flat so it stands on its own. This type of matrix can be cut easily with an inexpensive tile saw.

Edited November 16, 2013 by Ridgehiker

[rejd]

I agree with northstar. I would leave it as it is now. Flatten the base and it will display nicely.

[bluepickup]

Northstar and rejd, thank you for your comments.

I will leave it as is except to flatten the bottom. I think I will be able to flatten a section so the crinoid is visible as well.

Northstar, thanks for the tip about Composita being a broad term. My only reference book shows one like this one in the photo below. I didn't realize there would be others called the same. I found it near the same location as the other, but it just popped all the way out.

I thought was going to be able to ID my fossils fairly easily, but I'm finding it's going to take a long time. I have a lot to learn.

[Ridgehiker]

The brach in your matrix appears to be a Composita...the one above a bit like a Cleiothyridina.

However...these are the same order of brachs. It's hard to be specific about a brach when it comes to species. We would do serial grinds (destroys the specimen) to see the internal structure. Otherwise externally some brach from the Devonian, carboniferous, etc. can look more or less the same as one found 350 million years later in the oceans today.

[mikeymig]

YES. I always try to leave them in matrix because it makes for a better display. I agree that you should grind the bottom to make it more stable and clean the brach a little more.

Mikey

[erose]

As mentioned Composita ovata is a good identification ID. But if you get into the reference books the other species listed are extremely similar and you almost always need a large sample to sort them out. The length versus width, depth of fold/sinus, etc all need to be looked at. Personally I suspect they are almost all one species with a wide amount of intraspecific(sp?) variation.

This paper helped me with similar fossils from the Pecos and Santa Fe areas. http://geoinfo.nmt.edu/publications/monographs/memoirs/27/

[bluepickup]

Thanks for the link erose.

It should boggle my mind for some time.

[caldigger]

...or you could just say, "Hey look at my neat shell fossil" and call it good. Lol!

[Krazy Rick]

YES. I always try to leave them in matrix because it makes for a better display. I agree that you should grind the bottom to make it more stable and clean the brach a little more.

Mikey

I agree Mikey, I think they look much better left with matrix

[hrguy54]

I've prepped a lot of specimens over the years, sometimes the item will just pop right out of the matrix, sometimes it doesn't go well at all. Yours isn't "popping out". I tend to leave as is the Brachs that are embraced by a lot of matrix, they just don't seem to separate from the limestone as well as other specimens. And even if I can successfully separate they don't show as well because the separation process has marred the piece.

My suggestion is: work on/experiment with those that are less "attractive". If they don't turn out so well, no loss. In time you'll figure out what to do with this one and future finds.

[Herb]

I think Eric has the right ID as Composita ovate.

[erose]

I would also leave it in that matrix. Maybe flatten a surface so that it stands up nicely for display and then only do a little picking around the edges to sharpen it up. And if you found that one, nicely preserved in matrix you are likely to find some good loose ones in the same location. Try looking in the loose soil and talus if this was on a slope or in spots where water has washed over the rocks and sorted out stuff. Composita, in my experience, is always found in some quantity.

[Uncle Siphuncle]

My experience is that hard Paleozoic limestones don't prep well by mechanical means, at least with my skill set and tools available. I do more damage than good sometimes. So, still cringing over past failures, I am now much more apt to take a light handed approach to potentially deleterious prep.