Scallop-Like Fossils Id Needed

[danco]

Here is a bunch of shells for whom I need ID, please. They are from Terlingua, TX, the matrix is a very hard mudstone, impossible to detach (I tried boiling, heating in the oven then putting in ice, repeatedly with no result). The piece is 4.5 cm. One can also see two kind of Bryozoa.

[MikeD]

Looks like sea floor hash. The shells look mostly like brachiopod pieces, although I don't know the species.

[Auspex]

Brachiopods, bryozoans...very nice!

I like them in the matrix, just the way they are

[danco]

Brachiopods, bryozoans...very nice!

I like them in the matrix, just the way they are

Me too, esp. because I couldn't detach them (:-)

[tracer]

west part of the terlingua area is an uplifted area of older stuff along a fault line. santa elena formation.

[BobWill]

west part of the terlingua area is an uplifted area of older stuff along a fault line. santa elena formation.

this would explain the earlier post with the possible crinoid stem sections.

[tracer]

this would explain the earlier post with the possible crinoid stem sections.

yes maybe, but i erred. the newer stuff fell down rather than the older stuff jumping up.

[Han]

The look like members of the molluscan family Pectinidae

[JohnJ]

Danco, did you find these yourself? They look like Pennsylvanian age specimens.

[Auspex]

The brachiopods look something like Dinorthis pectinella, a Mid Ordovician species.

[JohnJ]

The brachiopods look something like Dinorthis pectinella, a Mid Ordovician species.

...or Pennsylvanian Derbyia sp.

[danco]

Danco, did you find these yourself? They look like Pennsylvanian age specimens.

No, John. I bought it.

[danco]

...or Pennsylvanian Derbyia sp.

What about Strophomena (Tetraphalerella) or Rafinesquina ?

[tracer]

man i just don't know where the paleozoic stuff came from around terlingua, lessen a miner found it down a hole or sompin...

[tracer]

p.s. - um, there's a store in terlingua, or at least there was when i was there, and locals were sitting on the porch outside drinking um, cerveza, and strumming their guitars and such, and so anyway, before i went and sat with them and basted myself with local culture, i got a coupla books from teh store. and one of those books was The Big Bend of teh Rio Grande - a guide to the rocks, landscape, geologic history, and settlers of the area of big bend national park. by ross a maxwell. guidebook 7. by the bureau of economic geology of the university of texas at austin (which if i recorrember ectly is a school taht folks go to if they think they need to know more after high shcool and they can't get into Texas A&M.

whut?

anyhoo, teh book has a cool pocket thingee inside the back cover that gots a hum ongous(!) freaking geological map of the area and some other ancillary paper diagrammatical stuff. the goodest thing about this book is that number one, you always feel kinda smug and edumacated when you buy a book all scholarly seeming, but number two, it was only 19.95 according to teh price sticker taht for some reason is still on the back of the book. and it's got the numbers 0121 on the top of the sticker and i have no idea why, so if ya'll ever go to the store in terlingua (dont' ask WHICH store -they's only one) would you ask whoever works there what those numbers on that sticker mean and pm me and tell me.

thanks.

[JohnJ]

No, John. I bought it.

I think the seller may have the location mixed up. I doubt those are from Terlingua. If you have this book you can compare your find to Derbyia.

[danco]

I think the seller may have the location mixed up. I doubt those are from Terlingua. If you have this book you can compare your find to Derbyia.

I am not an expert but I found similarities also with Strophomena (Tetraphalerella) and Rafinesquina. What do you think?

[JohnJ]

I am not an expert but I found similarities also with Strophomena (Tetraphalerella) and Rafinesquina. What do you think?

Not sure. Maybe erose or thair will weigh in with their experience.

[erose]

Not sure. Maybe erose or thair will weigh in with their experience.

Dang. Been put on the spot.

OK, here goes: Ain't NO freakin' way it's from "west of Terlingua" unless by west you mean all the way back around the globe to some Paleozoic local in maybe Pennsylvania. Well that's overstating it a bit...

The fossils appear to be brachiopods and there is a definite fenestrate bryozoan there as well. These are VERY typical Paleozoic fossils and folks have suggested anywhere from the Ordovician to the Permian. And without accurate locality info...well, lord only knows. And I don't know of any Cretaceous brachs or bryoas that come close to those from our western interior sea.

Now I also have that great big map of Big Bend geology that Tracer mentioned (Mine don't got nuttin on the back...sorry Tracer no help there.) and there is only one designated color for anything Paleozoic and I can't even find it anywhere on that map, let alone, "west of Terlingua." I even dug out the Emory Peak-Presidio Texas Geo Atlas Sheet which gives a broader view of the region and the nearest Paleozoic stuff from what I could tell at a fairly brief glance, is either north east of Terlingua in the Marathon Uplift or way north west near El Paso. Not close by most folks standards but maybe purtty close by Texas standards. (tracer's got me slumming again...)

I believe a good handful of brachiopod species have been suggested, ranging over the mentioned Paleozoic periods. Most would be good guesses if the age of the rock was known.

So I suggest you just keep it as a nice "keepsake specimen of unknown providence" or if they got you for a bunch of money go back and ask for that money back. But then those folks down that way spent way too much time mining Mercury and maybe they should not be bothered too much since there is a way to much space available to get rid of a pesky visitor from somewhere else....

Oh and I don't think it's mudstone. Try some vinegar, I bet it's limestone.

Edited February 16, 2011 by erose

[danco]

Dang. Been put on the spot.

OK, here goes: Ain't NO freakin' way it's from "west of Terlingua" unless by west you mean all the way back around the globe to some Paleozoic local in maybe Pennsylvania. Well that's overstating it a bit...

The fossils appear to be brachiopods and there is a definite fenestrate bryozoan there as well. These are VERY typical Paleozoic fossils and folks have suggested anywhere from the Ordovician to the Permian. And without accurate locality info...well, lord only knows. And I don't know of any Cretaceous brachs or bryoas that come close to those from our western interior sea.

Now I also have that great big map of Big Bend geology that Tracer mentioned (Mine don't got nuttin on the back...sorry Tracer no help there.) and there is only one designated color for anything Paleozoic and I can't even find it anywhere on that map, let alone, "west of Terlingua." I even dug out the Emory Peak-Presidio Texas Geo Atlas Sheet which gives a broader view of the region and the nearest Paleozoic stuff from what I could tell at a fairly brief glance, is either north east of Terlingua in the Marathon Uplift or way north west near El Paso. Not close by most folks standards but maybe purtty close by Texas standards. (tracer's got me slumming again...)

I believe a good handful of brachiopod species have been suggested, ranging over the mentioned Paleozoic periods. Most would be good guesses if the age of the rock was known.

So I suggest you just keep it as a nice "keepsake specimen of unknown providence" or if they got you for a bunch of money go back and ask for that money back. But then those folks down that way spent way too much time mining Mercury and maybe they should not be bothered too much since there is a way to much space available to get rid of a pesky visitor from somewhere else....

Oh and I don't think it's mudstone. Try some vinegar, I bet it's limestone.

Thanks erose for yours enlightening me. I paid a couple of bucks, no problem. So, what would be your educated guess for genera? It's not limestone (neither vinegar nor hydrochloric acid reacts). It silicate, kind of hard marl or silt?

[erose]

Thanks erose for yours enlightening me. I paid a couple of bucks, no problem. So, what would be your educated guess for genera? It's not limestone (neither vinegar nor hydrochloric acid reacts). It silicate, kind of hard marl or silt?

Without locality info I can only offer these points:

From what I can tell all the shells are brachiopods, maybe 2-3 genera present. There are a bunch of genera that match those flat ones with the radiating ribs. Derbyia are certainly quite common in certain formations. But there is a small Rafinesquina from the Cincinnatian that is similar as well.

I see at least two types of bryozoans, the fenestrate type on the front and a branching type on the back and maybe some much smaller stuff as well.

When I look at photo #2 I see a scrap of a brachiopod that has radiating detail superimposed over larger radiating costae. I am not familiar with anything like that in the Ordovician that I have collected or studied (OH, NY & OK). I do know stuff like that from the Devonian (NY) and the Pennsylvanian (TX & NM). One suggestion would be to find books that describe specific faunas for different places and see if you can match up the two obvious brachiopod types as well as the two bryozoans.

If you can get your hands on a copy of Index Fossils of North America I would suggest just sitting down and going thru it page by page noting all the ones that appear to match and then seeing if more than one come from the same rock group.

Without accurate locality information that would be the best you could do.

[tracer]

um, i dint say no brachiopoda was hangin perzactkly with the rudistids or nothing over to the santa elena stuff. i just kinda implied that teh older stuff was over thataway so go dig over there sort of. they was mercury miners. i gots no idee how deep they was diggin...

[erose]

um, i dint say no brachiopoda was hangin perzactkly with the rudistids or nothing over to the santa elena stuff. i just kinda implied that teh older stuff was over thataway so go dig over there sort of. they was mercury miners. i gots no idee how deep they was diggin...

Oh, I didn't think you said it was from west of Terlingua. I was just picking up on the general discussion about what rocks it might be from and then when I went to the maps realized it probably wasn't from Terlingua at all. And now all this talk of Terlingua has me itching to get back down there again. I found a mosasaur just up Terlingua Creek from the bridge a few years back. had to collect it with a camera but still the only articulated vertebrate fossil type thing I've ever found.

[tracer]

i know. i went back last nite and looked at all my pictures from that area and it's just spectacularly cool.

[danco]

Without locality info I can only offer these points:

From what I can tell all the shells are brachiopods, maybe 2-3 genera present. There are a bunch of genera that match those flat ones with the radiating ribs. Derbyia are certainly quite common in certain formations. But there is a small Rafinesquina from the Cincinnatian that is similar as well.

I see at least two types of bryozoans, the fenestrate type on the front and a branching type on the back and maybe some much smaller stuff as well.

When I look at photo #2 I see a scrap of a brachiopod that has radiating detail superimposed over larger radiating costae. I am not familiar with anything like that in the Ordovician that I have collected or studied (OH, NY & OK). I do know stuff like that from the Devonian (NY) and the Pennsylvanian (TX & NM). One suggestion would be to find books that describe specific faunas for different places and see if you can match up the two obvious brachiopod types as well as the two bryozoans.

If you can get your hands on a copy of Index Fossils of North America I would suggest just sitting down and going thru it page by page noting all the ones that appear to match and then seeing if more than one come from the same rock group.

Without accurate locality information that would be the best you could do.

I think Derbyia is too big (25 mm large). The size of my brachi is 13 mm wide and 10 mm high, and for that reason I am inclined to think they are Onniella (meeki?)