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weird circular imprints (Formosa Reef, Lower Devonian)


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Hi all!

 

Yesterday I visited Formosa Reef here in Ontario (Amherstburg Formation, Lower Devonian), and I found these weird circular imprints on a few rocks - does anyone know what they are?  @Kane

 

Thanks a bunch!

 

Monica

 

photo with ruler for scale:

DSC01960.thumb.JPG.0e0dab22c088ce992d73becb77bff430.JPG

 

close up photos:

DSC01962.thumb.JPG.4bda2cfefd5519703d597bd5c4b0bf1b.JPGDSC01961.thumb.JPG.8aeda58e36fb131b7785d76c98ee3007.JPG

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I'd say Syringostroma cylindricum

 

It compares well with this image from:

Fagerstrom, J.A. (1961). The Fauna of the Middle Devonian Formosa Reef Limestone of Southwestern Ontario. Journal of Paleontology, Vol. 35, No. 1 (Jan., 1961), pp. 1-48

 

PS -- Sorry about the mess I left, but the boar-sized block's removal hopefully revealed the more fossiliferous material. :P 

 

Edit: species name corrected!

Screen Shot 2020-05-23 at 3.30.05 PM.png

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Wow, thanks, @Kane!  That was quick!!!

 

I just Googled it and found out that Syringostroma cylindri is a stromatoporoid - I don't have many of these so that's exciting - yay!!! 

 

Re: the "mess" you left - there were some loose orthoconic nautiloid chunks for me, and some loose gastropods (one small, beautiful, and complete!) for Viola, so we were both pleased and wanted to thank you for exposing those rock chunks to the elements for us :)

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I'm guessing someone must have been there between our visits -- I had also left a shelf of about 30 or so trilobite pygidia. But I'm happy some of the other specimens I left as spoils were still there for you.

 

The chunk I removed was on the windward side, lower flank and a bit beneath the more productive jointing (which is where more of the larger specimens seemed to appear). An exception is a busier large brachiopod and bivalve layer at about the midpoint between ground and the current bench, but it is likely just a pulse. The crinoidal packstone gets a bit more "shredded" with a kind of smaller grain size appearance as you head lower and southward, while the matrix becomes much tougher and less cooperative (the colour gets drained of the orange and becomes a kind of buff to dark grey).

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Oh, and in terms of stromatoporoids, there may be some much bigger species if you climb to the peak as that is effectively a stromatoporoidal cap which sometimes was subaerially exposed. But they will be tough as the dickens to extract!

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Tidgy's Dad

I've got Syringostroma cylindricum? 

Nice find, Monica.:)

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5 minutes ago, Tidgy's Dad said:

I've got Syringostroma cylindricum? 

Have you spoken to your doctor about that? :P 

But, yes, it is indeed cylindricum. A major typo when I posted in haste, post haste, attributable to an error of the copy/paste! :DOH::D 

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Tidgy's Dad
Just now, Kane said:

Have you spoken to your doctor about that? :P 

Indeed. She seems to think that having Syringostroma cylindricum is a good thing. 

I would tend to agree. 

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You find some of the most interesting things up there!

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2 minutes ago, Tidgy's Dad said:

Indeed. She seems to think that having Syringostroma cylindricum is a good thing. 

I would tend to agree. 

Well, she hopefully told you that the long-term effects include slower growth, but with impressively resistant skeletal tissue. :D 

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FossilNerd

Awesome find Monica! I’m glad you were there to pick up after Kane. He’s a messy boy and leaves some of the best stuff just laying around! :P

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1 hour ago, Kane said:

I'm guessing someone must have been there between our visits -- I had also left a shelf of about 30 or so trilobite pygidia. But I'm happy some of the other specimens I left as spoils were still there for you.

 

You're probably correct about someone having been there between our visits because there were a few Crassiproteus crassimarginatus pygidia here and there, but certainly not 30 of them, and certainly not all in one spot.  But that's okay - I picked up a few, and so did Viola, and we're content with what we found.

 

I just looked at my specimens and I think I found what appears to be either a tentaculitid or a very small cyrticonic nautiloid - I'll post pictures in bit and call you over to have a look - it's really adorable :wub:

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1 hour ago, Kane said:

Oh, and in terms of stromatoporoids, there may be some much bigger species if you climb to the peak as that is effectively a stromatoporoidal cap which sometimes was subaerially exposed. But they will be tough as the dickens to extract!

 

Um, no thank you.  I have a bit of a fear of heights, and so does Viola, so we'll stick to the lower parts of the reef.  Plus, we're not quite as strong as you, so the bit of hammering that we do at the lower levels is quite enough for us.  We're also really happy with surface collecting, so searching through your spoil piles is great for us! :D

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1 hour ago, Tidgy's Dad said:

I've got Syringostroma cylindricum? 

Nice find, Monica.:)

 

1 hour ago, GeschWhat said:

You find some of the most interesting things up there!

 

53 minutes ago, FossilNerd said:

Awesome find Monica! I’m glad you were there to pick up after Kane. He’s a messy boy and leaves some of the best stuff just laying around! :P

 

Thank you all!

 

And we did try to clean up after @Kane, but he can move quite a lot of rock in a short amount of time, so there are still plenty of loose rocks to search through if anyone is interested. :)

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10 minutes ago, Monica said:

 

Um, no thank you.  I have a bit of a fear of heights, and so does Viola, so we'll stick to the lower parts of the reef.  Plus, we're not quite as strong as you, so the bit of hammering that we do at the lower levels is quite enough for us.  We're also really happy with surface collecting, so searching through your spoil piles is great for us! :D

:D 

Well, when next I go maybe I'll bucket a few of those for you. I was afraid of heights, too, but that seemed to change over time. Get Viola on a serious training regimen with lots of protein, LOL. But in all seriousness, I can make the climb. That being said, if you tuck into the back area, it is much easier to access the top without having to do any Ralph-like climbing. 

 

And duly noted about surface stuff. Next time I go, I'll make a secret cache, give you a nudge and you can take it all! My last visit was mostly about leaving things out for others such as yourself. I must have fallen down on not giving a head's up!

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Hi again, @Kane!

 

Here is the little tentaculitid or cyrticonic orthoconic nautiloid...

DSC01973.thumb.JPG.d993bc53ef965574582578440173d94a.JPGDSC01974.JPG.423f84f4275e7213d07e7b120743d17c.JPGDSC01979.thumb.JPG.4feea9ee2922c5248c8a66647188971c.JPG

I'm now thinking that it's a nautiloid because there is a clear circle in the centre of the specimen (as can be seen in the photo of the base of the specimen), so I'm assuming that might be the siphuncle?  Unless a tentaculitid has such a structure...?  I'll tag Adam @Tidgy's Dad, too, since he'd probably like to have a look as well.

 

By the way - Viola's protein consumption is very good - I think her favourite food is meat, and she LOVES milk, so as I get older she'll be able to do all of the hard work while I wait for her to bring me smaller chunks of rock to hammer in the shade :P

 

Edited by Monica
changed "cyrticonic" to "orthoconic"
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Tidgy's Dad

Thanks, Monica. :)

Yes, I'm pretty sure that's a siphuncle, so nautiloid internal mold. 

In tentaculitids the ornamentation is exterior, so an internal mold wouldn't show any chambers. 

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Thanks, Adam @Tidgy's Dad!  I think that's my most complete cyrticonic orthoconic nautiloid, and it's my smallest, too :wub:

Edited by Monica
changed "cyrticonic" to "orthoconic"
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Adam beat me to the punch, but only because I was on the phone! :P 

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Tidgy's Dad
2 minutes ago, Kane said:

Adam beat me to the punch, but only because I was on the phone! :P 

I have an advantage.

I don't have a phone. :)

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13 hours ago, Tidgy's Dad said:

I have an advantage.

I don't have a phone. :)

To be fair, it was an actual phone, a landline (not one of those infernal "smartphones"). I have a fulsome cyrticonic from there I'm willing to trade for some Georgian Bay bugs.:rolleyes:

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1 hour ago, Kane said:

To be fair, it was an actual phone, a landline (not one of those infernal "smartphones"). I have a fulsome cytriconic from there I'm willing to trade for some Georgian Bay bugs.:rolleyes:

 

We have a landline, too - they seem to be a rare piece of technology these days!

 

Re: Georgian Bay bugs - I wish I had more than the lonesome Flexicalymene that I have!  But if I find another, I will definitely let you know!  (Now I'm inspired to find another, but I need to find some new locations - I'll see what I can do... :))

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It has your name on it if you strike it trilo-lucky in your creeks!

PA200486.JPG

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Tidgy's Dad
2 minutes ago, Kane said:

It has your name on it if you strike it trilo-lucky in your creeks!

You're not wrong!

PA200486.thumb.JPG.6a6d69d1fc9969e1d7f51d33e65647bc.thumb.jpg.fc2499d8ca8c3319dbea6adbceeeb535.jpg

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You've a fantastic eye for details, Adam! :D How did I miss that? :P 

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