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Hi all!

 

After reading about @Kane's autumn trip to Ontario's Formosa Reef (Amherstburg Formation, Lower Devonian), I was inspired to find it and check it out myself.  With the help of Ludvigsen's 1986 paper entitled "Reef trilobites from the Formosa Limestone (Lower Devonian) of southern Ontario," along with Google Maps' Satellite View, I was able to locate the reef, so Viola and I made the 2-hour drive yesterday to search the site for some new fossils.

 

Here's Viola standing atop the reef:

DSC01255.thumb.JPG.764fabf8b11469c5e1800b218b7266b9.JPG

 

This was my first find of the day - a rock with a brachiopod AND a gastropod in it - woohoo!!!

DSC01258.thumb.JPG.f30e712548292acd83733ea27d5376c3.JPG

 

This was one of Viola's first finds of the day and probably her favourite - a large and beautiful chunk of tabulate coral:

DSC01259.thumb.JPG.14d542b1a5b94b4b44c227cfa234a951.JPG

 

Here is a photo of Viola and I just before we left the site after about 3 hours of fossil-hunting:

DSC01260.thumb.JPG.c5f563338b788757d77d7a653fafecb8.JPG

 

Photos of the fossils to come...

 

 

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Trilobite material:

 

Specimen #1: I'm assuming this a part of a trilobite, but I'm not sure.  Hopefully @piranha and/or @Kane can provide some insight:

DSC01263.thumb.JPG.0f4ef35875cdcd9023daefceea4620d4.JPG

 

Specimen #2: a free cheek of Crassiproetus crassimarginatus: 

DSC01264.thumb.JPG.6bd6d6f2c5e619d12928ff12759f1b75.JPG

 

Specimen #3: a cranidium of Crassiproetus crassimarginatus: 

DSC01265.thumb.JPG.152e366d1d3786437ca0d46cda5c3438.JPG

 

Specimen #4: a pygidium of Crassiproetus crassimarginatus: 

DSC01266.thumb.JPG.cd0e5177f78f48f00ec5b5a2f4943e13.JPG

 

Specimen #5: a pygidium that I think is from Mannopyge halli but I'm not sure:

DSC01267.thumb.JPG.ea617bc795a2fcfed25ad71d6b85ae84.JPG

 

More fossils to come...

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Manticocerasman

nice report :popcorn: quite a  lot of trilobite stuff

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Mollusc material - I was hoping to find some specimens as stunning and large as @Kane found back in the autumn, but it just wasn't meant to be:

 

Specimen #6: an imprint of a slightly curved orthoconic nautiloid:

DSC01274.thumb.JPG.a822f4209e42092323ceeaa7803b3bf4.JPG

 

Specimen #7: an actual specimen of a slightly curved orthoconic nautiloid:

DSC01275.thumb.JPG.c72c4441932f0ae313728634324956ee.JPG

 

Specimen #8: a small chunk of an orthoconic nautiloid that's not curved:

DSC01277.thumb.JPG.be4a2433ea56ff82083cba0c9eb35000.JPG

 

Specimen #9: a couple of gastropods:

DSC01282.thumb.JPG.19336a4d91e9a9ed63c0fe498e03e359.JPG

 

More fossils to come...

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More mollusc material:

 

Specimen #10: a rostroconch (I think):

DSC01270.thumb.JPG.d8cbec115d7157cf67bb9af8d56175b0.JPG

 

Specimen #11: a rostroconch imprint (I think):

DSC01271.thumb.JPG.7911facf1ed54cbcc83c8cde6b22155d.JPG

 

Unknown material:

 

Specimen #12: this is on the same rock as Specimen #11, and it may be nothing, but I thought I'd post a picture of it just in case it's something - it appears to have some curved layers to it:

DSC01273.thumb.JPG.0b4772261b61d8a398d49756251562c3.JPG

 

Coral material:

 

Specimen #13: "front" and "back" of a nice chunk of tabulate coral:

DSC01279.thumb.JPG.c00fb7803b2d0b639d83ed4c7848abfd.JPGDSC01280.thumb.JPG.4567b3558e4ce50db72097605efb0e20.JPG

 

Thanks for having a look!

 

Monica

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13 minutes ago, Manticocerasman said:

nice report :popcorn: quite a  lot of trilobite stuff

 

Thanks, Kevin! :)

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Just now, hokietech96 said:

Looks like you had a lot of fun yesterday!!  Great pictures!

 

Thanks, Mark!  We did have fun yesterday - the weather was cool but sunny and dry so it was perfect for fossil-hunting, and we encountered no one so it was a great way to spend the day given the current recommendations to isolate ourselves from others due to coronavirus.  We'll definitely check out this location again in the future! :dinothumb:

 

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Congratulations. Looks like you and Viola had an excellent time on a beautiful sunny day. Love the big tabulate coral (Favosites?) and those partial trilobites look interesting- different species than the ones I'm used to finding in the Devonian.

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Good show. You may find J.A. Fagerstrom's paper on the reef helpful. Kenneth Klein has also committed time to the type section. 

More recently, a dissertation by Kim Kyou performed a section-by-section analysis (10 in total from leeward to windward side).

 

Kyou, K. (1992). A microfacies study of the sedimentology and diagenesis of the Formosa Reef Limestone (Middle Devonian), southwestern Ontario. 

 

And, to place it in context, Shuo Sun's even more recent study:

 

Sun, S. (2018) Stratigraphy of the Upper Silurian to Middle Devonian, Southwestern Ontario

 

Once we get our new car, we have designs on visiting there soon in addition to a few other unlisted outcrops of the same. Despite how distinct the Formosa reef bioherm is from the surrounding Amherstburg strata, it does not enjoy an official status as a stand-alone member even if it seems to deserve it! 

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Fossildude19

Great report, finds, and pictures, Monica!

Thanks for posting them. :) 

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minnbuckeye

I see that Viola is standing above  a large quantity of matrix worked over, in the first picture. Is her middle name "Kane"? NICE Finds!!! 

 

Mike

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Way to go... I have never been might try it one of these days

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@Monica Thanks for the great report. I'd love to have a peek at that site if the Corona thing has subsided in time for my planned visit mid June.

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1 hour ago, Jeffrey P said:

Congratulations. Looks like you and Viola had an excellent time on a beautiful sunny day. Love the big tabulate coral (Favosites?) and those partial trilobites look interesting- different species than the ones I'm used to finding in the Devonian.

 

It was a beautiful sunny day!  It was so nice to get outside and away from everything for a bit.  If travel by car within the province isn't restricted during this March/COVID-19 Break, I think Viola and I will try to make it up there one more time. 

 

1 hour ago, Fossildude19 said:

Great report, finds, and pictures, Monica!

Thanks for posting them. :) 

 

Thanks, Tim! :)

 

1 hour ago, minnbuckeye said:

I see that Viola is standing above  a large quantity of matrix worked over, in the first picture. Is her middle name "Kane"? NICE Finds!!! 

 

Mike

 

Hi Mike!  I imagine that the large number of loose rocks were leftovers from when @Kane was there in the fall - Viola and I spent about half of our time looking through those pieces, and then the other half of our time hammering some rocks ourselves.  While I pulled rocks out of the reef, Viola hammered some of the bigger pieces to see if anything was hiding inside.  It was a team effort. :D

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This Acanthopyge contusa hypostome is especially exciting ... Congrats on finding it! :fistbump:

image.png.66aa652a5d7bb7894a861db96c058389.png

attached for comparison is the hypostome of: Acanthopyge haueri

 

Thomas, A.T., Holloway, D.J. 1988
Classification and Phylogeny of the Trilobite Order Lichida.
Philosophical Transactions of the Royal Society of London, Series B 321:179-262  PDF LINK

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Great finds Monica, glad that you and Viola got out into some fresh air.

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1 hour ago, Kane said:

Good show. You may find J.A. Fagerstrom's paper on the reef helpful. Kenneth Klein has also committed time to the type section. 

More recently, a dissertation by Kim Kyou performed a section-by-section analysis (10 in total from leeward to windward side).

 

Kyou, K. (1992). A microfacies study of the sedimentology and diagenesis of the Formosa Reef Limestone (Middle Devonian), southwestern Ontario. 

 

And, to place it in context, Shuo Sun's even more recent study:

 

Sun, S. (2018) Stratigraphy of the Upper Silurian to Middle Devonian, Southwestern Ontario

 

Once we get our new car, we have designs on visiting there soon in addition to a few other unlisted outcrops of the same. Despite how distinct the Formosa reef bioherm is from the surrounding Amherstburg strata, it does not enjoy an official status as a stand-alone member even if it seems to deserve it! 

 

Thanks for the article recommendations, Kane!  And thanks for posting your fall field trip, because that's where I got the idea to visit the reef!

 

By the way - did you have a look at my fossil photos?  Did I identify the trilobite pieces correctly?  And did I actually find a rostroconch and an imprint of one?  

 

1 hour ago, Malcolmt said:

Way to go... I have never been might try it one of these days

 

Hey Malcolm!  It was very easy to get to the reef - it took 2 hours of driving, so a little less time than it takes to get to Arkona/HH from where we live.  It was well worth the drive. :dinothumb:

 

51 minutes ago, Ludwigia said:

@Monica Thanks for the great report. I'd love to have a peek at that site if the Corona thing has subsided in time for my planned visit mid June.

 

Hi Roger!  If everything re: coronavirus calms down and you actually make it here in June, it would be a great place for you to visit!  Perhaps we can go together...?  I could bring a picnic lunch (with brownies for dessert, of course :D)

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10 minutes ago, piranha said:

This Acanthopyge contusa hypostome is especially exciting ... Congrats on finding it! :fistbump:

image.png.66aa652a5d7bb7894a861db96c058389.png

attached for comparison is the hypostome of: Acanthopyge haueri

 

Thomas, A.T., Holloway, D.J. 1988
Classification and Phylogeny of the Trilobite Order Lichida.
Philosophical Transactions of the Royal Society of London, Series B 321:179-262  PDF LINK

 

WOW!!!  Thanks for the identification help!!!  In Ludvigsen's 1986 article mentioned in my initial post, there were no hypostomes included for Acanthopyge contusa, so I didn't know what it was.  Now I do, thanks to you!!!  :SlapHands:

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11 minutes ago, Nimravis said:

Great finds Monica, glad that you and Viola got out into some fresh air.

 

Thanks, Ralph!  It couldn't have been a better day!  (Well, actually it could've been better, if I had found a large, nice cephalopod!  But I'm not complaining, especially after finding out that I found a hypostome from a "rare" trilobite species from the reef!!!  I'm on Cloud 9 now!!! :yay-smiley-1:)

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14 minutes ago, Monica said:

 

By the way - did you have a look at my fossil photos?  Did I identify the trilobite pieces correctly?  And did I actually find a rostroconch and an imprint of one?  

 

The trilobite IDs are correct. And, yes, the rostroconchs are correctly identified. :dinothumb:

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1 minute ago, Kane said:

The trilobite IDs are correct. And, yes, the rostroconchs are correctly identified. :dinothumb:

 

Thanks once again, Kane!!!  That's my first rostroconch (and so here is my happy dance: :megdance::))

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For your records here is a printable chart of the hypostomal biometrics of Acanthopyge: copy-smiley.gif?1292867575

HL = sag. length of the hypostome
HLb = sag. length of the hypostomal body
HLp = length of the posterior hypostomal margin
HWa = tr. width of the anterior hypostomal margin (at anterior wings)
HWmax = maximal tr. width of the hypostome (at shoulders)
HWp = tr. width of the hypostomal posterior margin
HWba = maximal tr. width of the anterior lobe of middle hypostomal body
HWbp = posterior tr. width of the posterior lobe of middle hypostomal body

 

image.png.945cf5b6bd590cf89f9f546284bbf6a9.png

 

figure from:

 

Budil, P., Frýda, J., Chatterton, B.D E., Corbacho, J., Vokáč, V. 2016

Intraspecific Variability in Trilobite Acanthopyge (A.) haueri (Barrande, 1846) from the Middle Devonian (Eifelian) of the Barrandian area (Czech Republic).

[Innerartliche Variabilität bei dem Trilobiten Acanthopyge (A.) haueri (Barrande, 1846) aus dem Mitteldevon (Eifelium) des Barrandiums (Tschechien).]

3rd German Conference on Trilobites. [Ampyx-Verlag Publishing, Berlin, October, 8th and 9th 2016]. Abstracts of Lectures. pp. 8-11

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1 hour ago, Monica said:

Hi Roger!  If everything re: coronavirus calms down and you actually make it here in June, it would be a great place for you to visit!  Perhaps we can go together...?  I could bring a picnic lunch (with brownies for dessert, of course :D)

Sounds good to me :D

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