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Unusually Large Trilobite Fragment?


Kane

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While spending the morning just at my honey hole of assorted Devonian debris, I came upon this very weathered fragment. I have good reason to suspect it is a trilobite cephalon fragment (weathered to the point of being almost exclusively a mold/cast). In terms of species I have a few ideas, but what makes me quite uncertain is the sheer size of this one. I have certainly never found very large Devonian trilobites in the past, so this one seems a bit of a perplexing one for me - if it is indeed a trilobite specimen and I'm not just getting my hopes up and seeing trilobite where some large brach and a bit of rock shaping might be.

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...How to Philosophize with a Hammer

 

 

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The glabella, occipital ring and posterior border furrow are evident.  It appears to be a large dalmanitid.  Is this another Dundee find?

 

 

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Yes it is - and my thanks (particularly for confirming I wasn't just seeing things! I almost passed it over). My next step is to look at the literature to get a fix on which dalmanitid...

...How to Philosophize with a Hammer

 

 

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31 minutes ago, Kane said:

I have certainly never found very large Devonian trilobites in the past, so this one seems a bit of a perplexing one for me -

 

 

You did find a large 2 inch partial pygidium that fits well with this dalmanitid.  The Dundee dalmanitids are Coronura aspectans and Trypaulites calypso.

 

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Very true... I seem to be having a spot of luck around these parts recently. Better luck would be much better preserved and whole specimens, which would be the gold standard. Perhaps with a bit more persistence! 

...How to Philosophize with a Hammer

 

 

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A partial pygidium of 2 inches and a large partial cranidium ! Soon the entire trilobite i hope.

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"On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry)

"We only well see with the heart, the essential is invisible for the eyes."

 

In memory of Doren

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16 minutes ago, fifbrindacier said:

...and a large partial cranidium...

 

 

Actually it's a partial cephalon.  The cranidium is the central portion of the cephalon bounded laterally by the facial sutures.

 

 

 

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8 minutes ago, piranha said:

 

 

Actually it's a partial cephalon.  The cranidium is the central portion of the cephalon bounded laterally by the facial sutures.

 

 

 

Yes, i wanted to say that but i used the wrong word.:D

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"On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry)

"We only well see with the heart, the essential is invisible for the eyes."

 

In memory of Doren

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4 hours ago, fifbrindacier said:

A partial pygidium of 2 inches and a large partial cranidium ! Soon the entire trilobite i hope.

Lol... I'm getting it by instalments:D

 

 

...How to Philosophize with a Hammer

 

 

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And quickly following upon my little excitement of yesterday is another fragment, definitively Trypaulites calypso, from a different rock but same area. Found a few hours ago. It was a fairly productive day at my little hill.

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...How to Philosophize with a Hammer

 

 

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30 minutes ago, Kane said:

And quickly following upon my little excitement of yesterday is another fragment, definitively Trypaulites calypso, from a different rock but same area. Found a few hours ago. It was a fairly productive day at my little hill.

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The pygidium you found is not Trypaulites.  It is a Bois Blanc dalmanitid: Anchiopsis anchiops

 

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:o!

Well colour me corrected AND delighted! That just made my day, as it is certainly a new one for the collection! :)

...How to Philosophize with a Hammer

 

 

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The cephalon also fits better with an Anchiopsis anchiops ID.  Now we know you are collecting Bois Blanc, not Dundee.

 

 

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I knew some of the hill was riprap, but that must have been a long haul for some of this material (about 200 km away!). Bois Blanc does not outcrop in too many places, mostly near the Niagara escarpment. With some of it dumped here, I guess I don't have to go far to collect it! 

 

Now, there's this other trilobite from the BB I'm just dying to find, if at least a fragment of it... :D

 

Thanks again, Scott :fistbump:

...How to Philosophize with a Hammer

 

 

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You're lucky, thanks to share it with us.:D

theme-celtique.png.bbc4d5765974b5daba0607d157eecfed.png.7c09081f292875c94595c562a862958c.png

"On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry)

"We only well see with the heart, the essential is invisible for the eyes."

 

In memory of Doren

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This certainly changes everything. I've been double-checking some of the brachiopods I've found from the hill more carefully against the index species of the Bois Blanc. Also, of the five major genera of trilobites in the BB, I certainly have three of them so far (although two of those are not in themselves indicative of belonging to the formation in terms of necessary/sufficient condition, as they also appear elsewhere). The Anchiopsis seems to strongly suggest, alongside the index brachs and the sedimentary rock types, at least some of the rocks in this hill are BB in origin. I find that very exciting, and somewhat revelatory! 

I just got back from there a few hours ago and now I want to go back already.

...How to Philosophize with a Hammer

 

 

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Take the time to have a sleep between, or you'll take your toes for trilobites.:P

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"On ne voit bien que par le coeur, l'essentiel est invisible pour les yeux." (Antoine de Saint-Exupéry)

"We only well see with the heart, the essential is invisible for the eyes."

 

In memory of Doren

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