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Adam's Ordovician.


Tidgy's Dad

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Nice additions here Adam! I always like when my fossils have hitchhikers. Bryozoans like to cover everything, but you have a nice balance of bryo to brach ratio on that specimen. Maybe the bryozoan is some species of Monticulipora

 

Those spiky Parvohallopora ramosa are wonderfully detailed. Beautiful specimens. :wub: 

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3 hours ago, FossilNerd said:

Nice additions here Adam! I always like when my fossils have hitchhikers. Bryozoans like to cover everything, but you have a nice balance of bryo to brach ratio on that specimen. Maybe the bryozoan is some species of Monticulipora

 

Those spiky Parvohallopora ramosa are wonderfully detailed. Beautiful specimens. :wub: 

Thanks, Wayne. :SlapHands:

I don't think it's Monticulipora because the zooecia don't seem tightly packed enough and the only species I see listed for the formations found at Lawrenceburg are a domed one and a frondose one, no encrusting species.

There are a few candidates, but without thin sections, I don't think I'm confident enough to make a guess. 

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7 hours ago, Tidgy's Dad said:

Thanks, Wayne. :SlapHands:

I don't think it's Monticulipora because the zooecia don't seem tightly packed enough and the only species I see listed for the formations found at Lawrenceburg are a domed one and a frondose one, no encrusting species.

There are a few candidates, but without thin sections, I don't think I'm confident enough to make a guess. 

You are welcome. :) 


Most bryozoans are hard to ID, and as you say, it would probably take a thin section to make a confident guess anyway. So many look the same, or a single species can come in multiple forms. They can be real head scratchers. :headscratch: I still like the little buggers though!

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You've been acquiring a nice variety of specimens lately, Adam. I particularly like the Moroccan cystoid, the monoplacophoran and those latest bryozoans. The cystoid has been on my wishlist for a while but other things have taken priority, and now I've got a couple more things to add.. :fear:  (That is if there are more of those to go around... the bryo's are wonderfully detailed  :b_love1: )

Nice to see you've also gotten some of those graptolites from Mike and the scolecodonts from Monica, as I have too. It makes us seem like a small tight-knit community to see the same items in others' collections, but maybe it's more to do with the generosity of certain members that makes it seem so...

There are critters out there such as those worms that rather give me the willies... I wouldn't want to come across them live but somehow I don't mind coming across their fossils!

 

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13 hours ago, FossilNerd said:

You are welcome. :) 


Most bryozoans are hard to ID, and as you say, it would probably take a thin section to make a confident guess anyway. So many look the same, or a single species can come in multiple forms. They can be real head scratchers. :headscratch: I still like the little buggers though!

I agree. They can be a real nightmare, but I'm very fond of the bryozoa. They can be very beautiful indeed. 

9 hours ago, Wrangellian said:

You've been acquiring a nice variety of specimens lately, Adam. I particularly like the Moroccan cystoid, the monoplacophoran and those latest bryozoans. The cystoid has been on my wishlist for a while but other things have taken priority, and now I've got a couple more things to add.. :fear:  (That is if there are more of those to go around... the bryo's are wonderfully detailed  :b_love1: )

Nice to see you've also gotten some of those graptolites from Mike and the scolecodonts from Monica, as I have too. It makes us seem like a small tight-knit community to see the same items in others' collections, but maybe it's more to do with the generosity of certain members that makes it seem so...

There are critters out there such as those worms that rather give me the willies... I wouldn't want to come across them live but somehow I don't mind coming across their fossils!

 

Welcome back, Eric, missed you around here! :SlapHands:

Yes, I've been lucky enough to acquire some pretty nice and unusual specimens over the last few months. 

And yes, there are some members here who seem to have boundless generosity.:SunFace:

I think I would let a scolecodont bite me if I ever met one. To see what it's like. I wonder if they could actually puncture the skin? Or would it just pinch? Or would you not even notice? :zzzzscratchchin:

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  • 2 weeks later...

In the photo on the last page showing a huge amount of specimens of the bryozoan Parvohallopora ramosa you may also have noticed there are a few Vinlandostrophia brachiopods. These were sent to me by Ralph as I've been trying to work out which species are present at the Lawrenceburg road cut site. Vinlandostrophia was a very successful genus in the Late Ordovician and many species occur in the Cincinnatian, and quite a few in the Fairview Formation. But not all are found at every location, so which ones can we fine at Lawrenceburg? 

The new one I have identified from here is Vinlandostrophia crassa, three of which are shown here below three  V. laticosta which i have discussed previously in this thread. You will notice that V. crassa has a much more prominent fold, its maximum width is near to the centre, rather than at, or near to, the hinge line and the ribs are more rounded than those of V. laticosta. 

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Here are a V. crassa (left), a V. laticosta (right) and a V. hopensis, which is abundant in the Hope Member at this site, but is only about a centimetre wide.  

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Here they are again, this time shown above the comparatively huge V. ponderosa which can be found in the upper part of the Kope Formation that underlies the Fairview and may be found at the bottom of the roadcut. 

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A close up showing the huge fold in Vinlandostrophia crassa compared to V. laticosta.

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Vinlandostrophia crassa from different angles :

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Here are a few extra shots of the diminutive Vinlandostrophia hopensis : 

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  • 3 weeks later...

My good friend Mike @minnbuckeye recently sent me a whole bunch of delicious brachiopods from the Decorah Shale of Iowa?  :drool::brachiopod:

I'm busy cleaning them up at the moment, but here's a nice Stictopora bryozoan that's on the reverse of one piece of rock 

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Wonderful Vinlandostrophia there Adam! I’m still trying to work out some of the species with mine, and I think your show and tell has helped. Thanks! :D 
 

Not a bad little bryozoan either! :) 

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1 hour ago, FossilNerd said:

Wonderful Vinlandostrophia there Adam! I’m still trying to work out some of the species with mine, and I think your show and tell has helped. Thanks! :D 
 

Not a bad little bryozoan either! :) 

Thanks again, Wayne, I'm glad this is proving useful. There are many more species of Vinlandostrophia in the Upper Ordovician of North East America, some even from the same formations at other sites, it's very difficult, I'm still trying to navigate my way through them also. Currently going all the way back to their earliest appearance in the Decorah Shale.:brachiopod:

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As is usually the case in the Ordovician, orthids and strophomenids dominate the Decorah brachiopod fauna. 

Two of the most common orthids in the lower to middle part of the formation are Pionodema subaequata and Dorelorides pervetus.  

They are incredibly difficult to tell apart despite being members of different suborders, so very distantly related. Another wonderful example of convergent evolution, one assumes. As most of the differences are internal or along the hinge line and this is usually not visible in my specimens, most of these could be either species. Both species, especially P. subaequata, can have highly variable shell shapes so differentiating them can be next to impossible. 

However, usually, though not always, Doleroides has slightly thicker costae, so I think most of these are Pionodema subaequata which is the successor to P. conradi from the Platteville Formation which I posted previously. So that's nice. :)

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Note that the specimen on the right of the top row and the third specimen from the left on the row below that have thicker costae. I think these two maybe Doleroides pervetus.

Close ups of the specimens of Pionodema subaequata, many of them are a bit glooped up with matrix which is rather too resistant to my prepping.

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Fine detail of costae: 

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A second specimen :

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A third one :

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And a fourth :

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This specimen is just the pedicle valve : 5.thumb.jpg.befcaf139ef739e5f1d8176ef5b21091.jpg

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One in a rock :

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A smaller specimen (1.4 cm wide, the bigger ones are about 2 cm): 

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Others :

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A couple of squished ones : 

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This is the other side of the one shown above where the crushing has slid the two valves slightly apart revealing the delthyrium rather nicely : 

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A mold with a groove where the medial ridge would have been :

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An isolated valve but the matrix is too hard to prep out : 

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In matrix :

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I think these are Doleroides pervetus.

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Here is a specimen compared to a Pionodema subaequata, you can see that  Doleroides pervetus, on the right, has coarser costae : 

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Close ups :

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An isolated pedicle valve. Unfortunately wifey dropped her new camera phone on it and it broke, so it's been glued together very badly :shakehead: :

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The muscle scars and mantle canal system are very clear  :

5a.thumb.jpg.c751981c0674f65075dee3895f989c26.jpg

 

 

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Another orthid from the Decorah Shale is Dinorthis pectinella.

 1a.thumb.jpg.38719425422efb0eeaeb424227c22343.jpg

Here's the one in the middle :

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All three specimens are just isolated brachial valves, here's the interior of the one above :

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They are a bit gloopy but very hard to clean because despite having thick costae the valves are actually very thin indeed:

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Details of costae:

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Interior beak details :

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This second specimen is bigger but I broke it when prepping. :( Told you these were thin and fragile.

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This third specimen of Dinorthis pectinella has a bonus brachiopod stuck to it, during preservation, not an epibiont. 

it is the brachial valve of a Sowerbyella minnesotensis. 

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Here are some pics of the Sowerbyella minnesotensis. I also have this species from the overlying Cummingsville Formation which I posted previously in this thread.. it's 13 mm wide.

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These are not whole, but the short, triangular interarea, coarse ribbing and flat commissure is enough to show that they are Plectorthis plicatella. 

This first one is 16 mm wide.

There are little bits of echinoderm stuck to the shell which i actually rather like. 

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The slight bulbous bit at the end is where the animal actually was, the majority of the rest of the shell was empty except for the lophophore filaments. It alsways amazes me how small brachiopods actually are compared to the shell size.  

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The echinoderm ossicles :

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My second specimen of Plectorthis plicatella is only a bit of the brachial valve and the interarea. 

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The Late Ordovician and Silurian Platystrophia of North America have now been placed in the genus Vinlandostrophia but the Middle Ordovician genera have not. Only some of the genera from outside North America are still classifies as Platystrophia after the Middle Ordovician. 

This would seem to be because species such as P. bifurcatus can be found in the Cummingsville Formation in the USA, but also in the Baltic. It was only after the Middle Ordovician that the North American species became different enough to warrant their own genus. (see earlier in this thread for P. bifurcatus from Rochester, Minnesota given to me by Doren). 

The oldest species I have is this single specimen from the Decorah Shale, south of Decorah, Iowa. I'm delighted to have this one to add to my Platystrophia / Vinlandostrophia collection.:i_am_so_happy:

This is Platystrophia amoena.

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This is a lovely piece from the Decorah Shale with a group of different brachiopods in it : :wub::brachiopod:

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The one on the right I think might be a small Pionodema subaequata. See further up this page for more of this species. 

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In the middle is a rather nice little specimen of Hesperorthis tricenaria. 

For an even nicer and matrix free specimen see page 10 of this thread, but the specimen I presented there is from the Platteville Formation of Wisconsin, a little older than this Decorah specimen. 

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The other brachiopod on this rock is the strophomenid Oepikina inquassa which again is nice as I have the contemporaneous Oepikina minnesotensis 

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You can see some of the interior shell morphology peeking through the shell, muscle attachments and  median septum. 

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This piece is also on the rock, looks like a giant ostracod to me, but is probably a piece of brachiopod, maybe a fragment of Oepikina. 

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Keeping it quite literally in the family (and a closely related one as well)

So here are some larger strophomenids :

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The two at the bottom of the photo would appear to be the convex brachial valves of Strophomena, I'm not sure which species as the size and shape seem to fit S. trentonensis, but they could be S. filitexta which is more common in the Decorah Shale. They can only be confidently told apart by internal details. 

Here is the specimen on the bottom right :

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Lateral view :

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Anterior view :

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Details where outer layer of shell is broken off showing pseudopunctae :

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There's a nice little orthid articulation on this piece as well :

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The second specimen is rather more battered :

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And this third one is definitely a small Strophomena filitexta pedicle valve interior as the median septum does not continue to near the anterior edge as it does on S. trentonensis. 

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All sorts of smashed up shells and bryozoans in this rock :.

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And a very tiny gastropod :

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This rather crushed specimen would seem to be the thin shelled Rafinesquina trentonensis. 

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And on the reverse, maybe a Glyptorthis bellarugosa? 

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nd lots and lots of fragments of what i think are smaller Rafinesquina trentonensis. 

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And some Decorah Shale rhynchonellids : 

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The one on the left is Rhynchotrema ainslei which is smaller and flatter than the other rhynchonellids in the formation and has five costae on the fold. 

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The other two brachiopods in the fist photo in the post above are the much more rounded Rostricellula minnesotensis which has four costae on the fold. I also have this species from the underlying Platteville Formations. It has generally slightly fewer costae and a more rounded shape than the third common rhynchonellids in the formation, Rhynchotrema wisconsinensis which I have from the overlying Cummingsville Formation. 

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The other specimen:

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Finally, for the Decorah Shale, the eagle eyed amongst you would have noticed that this brach had a passenger in the rock :

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It's  a rather lovely Eomonorachus intermedius pygidium. 

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So thank you again my friend, Mike  @minnbuckeye for this and all the wonderful Decorah fossils posted above. :D

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