Adam's Ordovician.

[Tidgy's Dad]

1 hour ago, FossilNerd said:

Oh yes, and Lawrenceburg! 
 

I know right?! It would be an epic time and I would definitely find it hard to leave! I will get up to one of them (or all) some day soon, after the world gets back to some sort of normality. I’ve been talking to my wife about a day trip to hunt one of them. When I do, you will have a gift box coming your way!  

Thank you. 

[Tidgy's Dad]

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

Just a little bit of prepping :

The shells of Strophomena and Rafinesquina can look very similar but Strophomena has a convex brachial valve and concave pedicle valve while Vinlandostrophia has the opposite; a concave brachial valve and convex pedicle valve. 

Left centre below is a brachial valve exterior and to the right a lovely pedicle valve interior :

Close ups of the beak area of the pedicle valve showing the muscle scars : 

And of another specimen : 

Details of the anterior margin :

 

 

 

[Tidgy's Dad]

As often seems to happen with these pieces, the convex surfaces are uppermost on the top of the specimen and so on the underside you see the concave surfaces. 

So here's a pedicle valve and a half on  the underside of the same rock complete specimen is 2.7 cm wide : 

Close up of the pedicle area of the half specimen :

And two more specimens; a pedicle valve exterior and a brachial valve interior :

Details of the pedicle area :

 

And the interior of the brachial valve articulation region :

 

 

[Tidgy's Dad]

Before moving on from St. Leon for a bit, I found these little objects on a fragment of brachiopod shell that had broken off the big hash plate.

At first i though they were microconchids, but it's the wrong time and place, I think and they don't look quite right.

Crionoid? Or another stalked echinoderm? Tiny holdfasts or just little columnals or segments of pinnules? 

I don't know. What do you think? 

Scale in mm. 

 

 

[Tidgy's Dad]

A quick visit to Sweden now.

The hash piece bottom right from Rattvik was mostly smashed up bits of shell, so I decided :

Here is a little piece I extracted, at first i thought it was a sponge, but can't find any listed for the formations occurring here which are mainly the Boda and Kullsberg Limestone Formations of the Upper Ordovician. So, the closest match would seem to be the weird cyclostome bryozoan Mitoclemella kullsbergiana, though i'm certainly not saying it is that. Scale in mm. 

From an auction win. @Kasia,  Do you know if this was the Amtjarn Quarry in Rattvik, please? 

The thing top right is a couple of echinoderm columnals, could be crinoid or cystoid as both are found in abundance here. 

[Tidgy's Dad]

Some crinoid/cystoid columnals (scale in mm) :

Bits of brachiopod shell : 

A sweet little orthid : 

 

[Tidgy's Dad]

And a slightly bigger brachiopod which may possibly be Siljanostrophia jaanussoni. 

[Tidgy's Dad]

And heading back to the USA via France, here are a lovely couple of orthids from the Landeyran Formation, Early Ordovician, Late Arenig/ Floian of Roquebrun, Hérault in the south of France. So these are my oldest orthids. 

They're Hesperonomia and can be found listed on the web as H.landeyranensis which would certainly make sense, but i can't find a reference to this in a paper so i'm going with Herperonomia sp. for now. 

Some close ups :

 

 

 

[Tidgy's Dad]

Some more Late Ordovician brachiopods in the next few posts, these ones all courtesy of my friend @Herb. Thank you again! 

First a nice size Herb Hebertella occidentalis pedicle valve from the Whitewater Formation of Mt. Washington, Kentucky: 

 

[Tidgy's Dad]

And some close ups : 

[Tidgy's Dad]

Back to St. Leon, Indiana, for a couple more Lepidocyclus perlamellosum, one of which is an internal mold.

  

[FossilNerd]

20 hours ago, Tidgy's Dad said:

Some more Late Ordovician brachiopods in the next few posts, these ones all courtesy of my friend @Herb. Thank you again! 

First a nice size Herb Hebertella occidentalis pedicle valve from the Whitewater Formation of Mt. Washington, Kentucky: 

That's a beauty!  From my neck of the woods too! 

[Tidgy's Dad]

13 hours ago, FossilNerd said:

That's a beauty!  From my neck of the woods too! 

Thanks, Wayne. 

Yes, I have a few from Kentucky, it's nice to have the same species from different places, too. 

For example these two Zygospira modesta are from the Whitewater Formation of Waynesville, Ohio and I also have the same species from Kentucky, Indiana and Ontario.(Canada in case anyone wonders if I think that's a US state)  

Can't seem to keep the little ones clear of dust and fibres today. 

 

 

 

[Tidgy's Dad]

And the smaller one : 

[FossilNerd]

1 hour ago, Tidgy's Dad said:

15 hours ago, FossilNerd said:

 

Thanks, Wayne. 

Yes, I have a few from Kentucky, it's nice to have the same species from different places, too.

That is always nice to have the same species from different areas. From different formations is nice as well.

 

I specifically meant that Mt. Washington was in my neck of the woods. It is less than and hour drive from my house. I was in that area on my last hunt, although I wasn’t in the Whitewater Formation.  

[Tidgy's Dad]

I think it's time for some molluscs. 

Bivalves, first. 

These are my oldest bivalves and are from the Late Ordovician Georgian Bay Formation of Etobicoke Creek, Mississauga, Ontario, Canada. Courtesy of various prizes and gifts directly or indirectly from @Monica So thanks very much for my oldest bivalve specimens! 

This first one is fairly easy to identify, as it seems to be the only one like it in the formation, the others are not so easy. 

So here is Ambonychia radiata. Biggest one is 4.4 cm long.

This last one is much smaller but much more detailed and there's the positive and negative : 

 

 

 

 

[Tidgy's Dad]

Here are a couple more Treptoceras crebriseptum. It's interesting that these beds produce such a lot of these and bivalves and comparatively few brachiopods or bryozoan like so many other Ordovician sites. 

The reverse has some interesting bivalve bits.

Many of the bivalves here belong to the family Modiomorphidae but there are several species and without more of the shell, I'm not sure which one. 

Here are some more on the reverse of the other Treptoceras block that I have:

 

[FossilNerd]

34 minutes ago, Tidgy's Dad said:

Here are a couple more Treptoceras crebriseptum. It's interesting that these beds produce such a lot of these and bivalves and comparatively few brachiopods or bryozoan like so many other Ordovician sites

That is quite the flip on fauna! The Ordovician spots that I hunt are about 80% brachiopod, 20% every thing else, and 110% bryozoan. Those little guys are all over everything! 
 

Love the dual Treptoceras crebriseptum. 

[Ruger9a]

Wonderful collection and photos as well!

[FossilDAWG]

Throughout most of the Paleozoic (after the Cambrian) brachiopods were very dominant in areas where the substrate was calcarious (eventually turning into limestone or calcarious shale) and the water held little suspended silt.  Bivalves on the other hand were more common in areas with a muddy sea floor and an influx of sediment.  Indeed many bivalves were infaunal (buried in the bottom sediment) and very few brachiopods did this, except for the lingulids.  So brachiopods dominate in limestone and other rocks with a lot of carbonate, and bivalves are more common in shales.  Of course brachiopods can be found in shales too but this was not their preferred habitat.

 

Don

[Tidgy's Dad]

Thanks, chaps. 

Here's another, bivalve from the same family but ftom the other locality in the region, Mimico Creek. At 7.4 cm the big one is quite a monster compared to most brachiopods of the time. 

Much of the shell is sadly missing, but some detail can be seen on the margins. I'm leaning towards Pholadomya pholadiformis for this one but it'll go down as a modiomorphid for now.

[Tidgy's Dad]

A rather smaller bivalve from Mimico Creek.

7 mm long.

Some of the members of the Modiomorphidae from this location, such as Colpomya faba pusilla didn't get bigger than a cm, though I'm not saying this is one. Could be a younger specimen of a bigger genera or something else entirely.

[Tidgy's Dad]

On the reverse of the piece with the very big bivalve is a jumble of bits of 

Ambonychia, modiomorphids and ichnofossils and/ or pieces of bryozoan and whatnot. I looked at the paper on Georgian Bay ichnofossils but I'm still uncertain.

Thanks so much, @Monica for all these lovely fossils.

[Monica]

1 hour ago, Tidgy's Dad said:

Thanks so much, @Monica for all these lovely fossils.

 

My pleasure, Adam 

[Tidgy's Dad]

Next up will be a dozen or so species of gastropod, also the oldest in my collection, all of them courtesy of my friend the magnanimous Mike @minnbuckeye

Here's a teaser :

 

Yuuummmmmmmmyyyyyyyyyyyyy!!!!!!!!!!!!!!!!!!!!!!!