Adam's Ordovician.

[doushantuo]

with regards to Don's sunday,2.18 h post:

 

image from:

Palökologie und Biostratigraphie der Pelecypoden des Unteren Mitteldevon (Eifelium) der Eifel
(Paleoecology and biostratigraphy of the lower middle devonian (eifelian) pelecypods of the Eifel Hills)Ursula Rehfeld 

Paläontologische Zeitschrift volume 63, pages251–262(1989)

 

great brachiopod pix Adam.

(they can be seen from outer space,I think)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Tidgy's Dad]

First up, though, is this little 'un which is on the reverse of one of my brachiopods from the Platteville Formation, Mifflin Member of Decorah, Iowa. 

I think it's Hormotoma gracilis and is 7 mm long. 

[Tidgy's Dad]

This one's also from the Platteville Formation but from Fennimore, Wisconsin. 

Clathrospira subconica : 

 

 

 

[Bobby Rico]

On 27/04/2020 at 12:28 AM, Tidgy's Dad said:

last of my brachiopods from St. Leon is Strophomena planumbona.

Some lovely stuff going down here and I really like this plate.  

[Tidgy's Dad]

21 hours ago, Bobby Rico said:

Some lovely stuff going down here and I really like this plate.  

Yeah, me too, it's very pretty.

This next one's interesting. 

It's Sinuites sp. a Bellerophontid gastropod from the Galena Group, Decorah Shale of Decorah, Iowa. 

Since I was a tiddler they have been moved from Gastropoda to Monoplacophora (now Tergomya, rather disappointingly) and back again several times. Currently, they are seen as basal gastropods, but there is still much debate. They are planispiral like the Tergomya and not torted like other gastropods.

 

[Tidgy's Dad]

A little Hormotoma gracils from Decorah. A lot of it has been preserved in tiny calcite crystals. 

[Tidgy's Dad]

This is Cyclonema textilis, an early member of the platyceratid family that later gave rise to well known Silurian, Devonian and Carboniferous forms such as Platyceras  and Spinyplatyceras, coprophages (dung eaters) one and all. 

 

[Tidgy's Dad]

A bit bigger are these Gyronema pulchellum with rather nice ridges on the whorls. 

 

 

 

 

[FossilNerd]

Love the gastropods Adam! I don’t know why, but I’m found of anything with a whorl. Especially the high spired type. 

[Tidgy's Dad]

21 hours ago, FossilNerd said:

Love the gastropods Adam! I don’t know why, but I’m found of anything with a whorl. Especially the high spired type. 

Thanks, Wayne! 

This is another high-spired species from Decorah. It's Fusispira, I think, but I'm not sure which one of the two or three species listed it could be. 

 

 

 

 

 

 

[Tidgy's Dad]

These next half dozen species are quite large specimens from the Stewartville Formation of the Galena Group, Fillmore County, Minnesota. 

Liospira vitruvia: 

 

 

 

[Kane]

Very healthy specimen, indeed! I rarely find Liospira at these sizes. 

[Tidgy's Dad]

On 6/30/2020 at 1:30 AM, Kane said:

Very healthy specimen, indeed! I rarely find Liospira at these sizes. 

Thanks.

But I don't think it's all that healthy. Pretty terminal, I'm fairly sure. 

This one's similar in size an shape, but slightly higher spired and has ridges on the whirls, so I think Trochonema umbilicata. 

 

 

 

[Scylla]

13 hours ago, Tidgy's Dad said:

Thanks.

But I don't think it's all that healthy. Pretty terminal, I'm fairly sure. 

This one's similar in size an shape, but slightly higher spired and has ridges on the whirls, so I think Trochonema umbilicata. 

 

 

 

Talented mollusc, it can type!

[Tidgy's Dad]

7 hours ago, Scylla said:

Talented mollusc, it can type!

In a rather limited way only using some punctuation keys. Mollusc language from the Ordovician, I suppose. 

Here is a high spired Hormotoma from Fillmore County that Wayne might like. @FossilNerd Much, much bigger than the little H gracilis from Decorah. 

Firstly is a photo with the two species side by side : 

 

 

 

 

 

 

[FossilNerd]

1 hour ago, Tidgy's Dad said:

Here is a high spired Hormotoma from Fillmore County that Wayne might like. @FossilNerd Much, much bigger than the little H gracilis from Decorah.

You were right! Wayne like! 

[Tidgy's Dad]

On 7/2/2020 at 12:41 AM, FossilNerd said:

You were right! Wayne like! 

Me too. Thanks. 

Here's another one, Fusispira inflata: 

 

 

 

 

[minnbuckeye]

On 7/1/2020 at 4:53 PM, Tidgy's Dad said:

little H gracilis from Decorah.

Adam, did I send you this one?? If so, it looks like it came from a site where all the gastropods have a crystalline coating. This site is NOT Decorah, rather Galena. 

 

PS, just checked postage. Still $185.00.   

[Tidgy's Dad]

1 hour ago, minnbuckeye said:

Adam, did I send you this one?? If so, it looks like it came from a site where all the gastropods have a crystalline coating. This site is NOT Decorah, rather Galena. 

 

PS, just checked postage. Still $185.00.   

I know. Ralph has the same problem and so does Germany. No more fossils for me for a bit. 

Luckily, I still have many to sort out, including this whole page of wonderful gastropods you kindly sent me a while back and a couple more I've yet to post. If you go to the last post on my previous page you can see all of them posted in a single photo with a big thank you to you. Thanks again, I think they're wonderful, such variety.

Yes, sorry, I meant from Decorah, the place, I get very confused with the stratigraphy of the area, it keeps changing : 

 https://ilstratwiki.web.illinois.edu/index.php/Galena_Group

https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=IAOg%3B0

[Tidgy's Dad]

This 'scroll snail' is one of my favourites. 

Subulites sp. 

I think it's lovely. 

 

 

[Tidgy's Dad]

And last, but not least from this location is this rather wonderful and large Maclurites sp. 

I love the fact that it has a flat side that looks chambered like an evolute, planispiral ammonite and the other side resembles an involute, sphaeroconic ammonite. 

This family also produced the largest known Ordovician gastropods. 

 

 

Marvelous. 

So that's twelve species of fantastic gastropods, thanks again to the generosity of my friend Mike @minnbuckeye

Cheers, Mike! 

 

 

[Tidgy's Dad]

Back to the Upper Ordovician of Lawrenceburg, Indiana for the next three gastropods, this roadcut has such a rich variety of species and I have a nice collection from here, thanks to Ralph, @Nimravis. It's one of my favourite fossil localities even though I've never been to it due to Ralph's excellent trip reports and the Dry Dredgers website, among others. 

Here are the snails :

 

[Tidgy's Dad]

The first one is a lovely little Sinuites cancellatus, one of those strange bellerophontids which are currently basal gastropods but may be tergomyids (Monoplacophora of old)

Some nice bryozoan and brachiopod bits in the aperture.

 

[Tidgy's Dad]

Next is Paupospira bowdeni. 

It's a bit squashed but some of the shell is still clinging on to the mold and you can see the whorl ridge in places. 

 

 

[Tidgy's Dad]

And finally, Cyclonema sp. 

After I'd poked it with a pin and removed the majority of the matrix and the bryozoan, which did survive intact. 

Cyclonema is an early platyceratid, the later members, like Platyceras itself, being pretty much stationary, often found attached to crinoids on which they were coprophagous. Cyclonema is occasionally found on crinoid calyces, but usually not, it is thought it was both a poop eater and a detritivore and moved about a bit. 

The genus is also interesting in that it is the only true gastropod in the Cincinnatian usually found with the shell intact, as the other gastropods had aragonitic shells, which are either dissolved or replaced by calcite so that only molds/ casts remain or much of the detail is lost, but Cyclonema's was calcitic and therefore fossilized with detail preserved. 

Also, Cyclonema is never found with the protoconch (tip/ primary whirls) as these dropped of during life unless anchored by an encrusting bryozoan. 

The preserved detail is astonishing.