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Malcolmt

As promised here is another of the specimens that I prepared that will be included in the new "Dawn of Life" gallery at the ROM. Not sure it belongs in the Preparation topic as I only have the single picture. Moderator feel free to move.  Those that know me realize that I hate taking pictures.

 

There are occasions when you get to work on a specimen that you absolutely do not want to return at the end of preparation. That was certainly the case with this one. Of all the specimens I have ever prepared for someone else, this plate is probably the one that I most wanted to keep for my own collection. This is natures art at its finest. This is in my opinion a stunning associated pair of trilobites a large Gabriceraurus hirsuitus (synomynous with G. dentatus) associated with a much smaller Ceraurus globulobatus. Hopefully a long awaited paper will be coming clarifying the naming of all these cheiridsThis specimen is the plesiotype for the species and is catalogued as ROM specimen 46105. This specimen was selected to be featured in the new permanent "Dawn of Life" gallery at The ROM opening late 2021 (Covid permitting). Thank you Dr. JB Caron for permission to share. This specimen was originally described in a paper by William Hessin back in 1988 and was collected Bill at Brechin Quarry in the 1980's
Truth in advertising. I was asked to do a repreparation and minor repairs to the specimen prior to public display in the gallery. Some preparation had been performed back in the 80's. I spent approximately 20 hours on this specimen. This work was done probono and was my pleasure and privilege to have been involved.
 
It was done exclusively under an Olympus SZ30 stereo microscope using a COMCO MB1000 air abrasion unit using only sub 40 micron baking soda. All work was performed with .015 and .010 nozzles at under 10 PSI. (Hence why it took 20 hours). A small amount of scribe work was performed using a Pferd MST31 with fine styl;us and a Paleotools microjack-2. Some Minor repairs were completed using Bob Smith Industries Instacure super thin cyanoacrylate and Milliput super fine white 2 part putty.
 
Unfortunately I only took a single picture . So here it is for your viewing pleasure. Definitely one of my favorites. Yes they are different species but as I was prepping this one I kept thinking of it as "Madonna and Child" So here here is what I refer to as "Madonna and Child"
 
Please feel free to ask questions or you can PM me directly
 
780194292_Gabrifinished.thumb.jpg.9119a3460a67e51e2549838aa5dab5ec.jpg

 

 

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This one is a classic example, and I felt privileged to see it in person at Chez Thornley. :) 
 

Your photo is much better, but I did snap this one last year:

19E4ABF7-1D19-4ED5-8474-735F769E9C5E.jpeg

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Tidgy's Dad

Stunning. :b_love1:

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daves64

:drool: UUummm sorry about the drool. Anybody got a towel? :blush:

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Top Trilo

With preps like these how can someone not be a trilo fan.

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connorp

:default_faint:

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historianmichael

Wow. Great work!

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piranha

:drool: :drool: :drool:

 

 

The synonymy of dentatus and hirsuitus will likely get reversed in the upcoming paper from Congreve et al:

 

"Hessin (1989) synonymized “Gabriceraurus” dentatus with “G.” hirsuitus because the original holotype of “G.” dentatus was lost. Lespérance and Desbiens (1995) argued that this was inappropriate taxonomic procedure and instead redescribed the species using the original paratypes as replacements for the holotype. We concur with Lespérance and Desbiens’ (1995) treatment of “G.” dentatus."

 

Congreve, C.R. 2013

Evolutionary Patterns of Trilobites Across the End Ordovician Mass Extinction.

PhD Thesis, University of Kansas - Department of Geology, 255 pp.  PDF LINK

 

 

"Hessin (1989, p. 1207) has used the taxon hirsuitus Ludvigsen, 1979b, as synonymous with dentatus Raymond and Barton, 1913, and as a replacement name for the lost holotype of dentatus (Bolton, 1966, p. 50). Furthermore, he stated that there is a single existing paratype pygidium (MCZ 7), and that it was not designated a neotype in view of the difficulty in using solely pygidia in (cheirurine) taxonomy. This unusual procedure of a "replacement" name has no justification in the Code of Zoological Nomenclature (Ride et al., 1985). What is perhaps more serious is that additional paratypes are extant besides MCZ 7 and a neotype is unwarranted and unjustified."

 

Lespérance, P.J., Desbiens, S. 1995
Selected Ordovician Trilobites from the Lake St. John District of Quebec and their Bearing on Systematics.

Journal of Paleontology, 69(4) Memoir 42:1-19

 

 

Hessin, W.A. 1989
Ceraurus and Related Trilobites from the Middle Ordovician Bobcaygeon Formation of South-Central Ontario, Canada.

Canadian Journal of Earth Sciences, 26(6):1203-1219

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Mainefossils

Absolutely beautiful. Amazing prep work! :)

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Malcolmt
1 hour ago, piranha said:

:drool: :drool: :drool:

 

 

The synonymy of dentatus and hirsuitus will likely get reversed in the upcoming paper from Congreve et al:

 

"Hessin (1989) synonymized “Gabriceraurus” dentatus with “G.” hirsuitus because the original holotype of “G.” dentatus was lost. Lespérance and Desbiens (1995) argued that this was inappropriate taxonomic procedure and instead redescribed the species using the original paratypes as replacements for the holotype. We concur with Lespérance and Desbiens’ (1995) treatment of “G.” dentatus."

 

Congreve, C.R. 2013

Evolutionary Patterns of Trilobites Across the End Ordovician Mass Extinction.

PhD Thesis, University of Kansas - Department of Geology, 255 pp.  PDF LINK

 

 

"Hessin (1989, p. 1207) has used the taxon hirsuitus Ludvigsen, 1979b, as synonymous with dentatus Raymond and Barton, 1913, and as a replacement name for the lost holotype of dentatus (Bolton, 1966, p. 50). Furthermore, he stated that there is a single existing paratype pygidium (MCZ 7), and that it was not designated a neotype in view of the difficulty in using solely pygidia in (cheirurine) taxonomy. This unusual procedure of a "replacement" name has no justification in the Code of Zoological Nomenclature (Ride et al., 1985). What is perhaps more serious is that additional paratypes are extant besides MCZ 7 and a neotype is unwarranted and unjustified."

 

Lespérance, P.J., Desbiens, S. 1995
Selected Ordovician Trilobites from the Lake St. John District of Quebec and their Bearing on Systematics.

Journal of Paleontology, 69(4) Memoir 42:1-19

 

 

Hessin, W.A. 1989
Ceraurus and Related Trilobites from the Middle Ordovician Bobcaygeon Formation of South-Central Ontario, Canada.

Canadian Journal of Earth Sciences, 26(6):1203-1219

There are lots of issues in the whole naming of cheirurines. I have had many a heated discussion with K. Brett and W. Hessin in this regard which is why I included hiruitus and Dentatus in the body of my post. Truth be known both myself and the ROM have been calling it Dentatus but I wanted to give Bill Hessin some acknowledgement so I went with the name hiruitus as well. Hessin has made significant contributions to Ontario paleontology and his work on "Fossils of South Western Ontario" is a must have and is still available for digital purchase directly from him. PM me if you need his contact information. 

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13 minutes ago, Malcolmt said:

There are lots of issues in the whole naming of cheirurines. I have had many a heated discussion with K. Brett and W. Hessin in this regard which is why I included hiruitus and Dentatus in the body of my post. Truth be known both myself and the ROM have been calling it Dentatus but I wanted to give Bill Hessin some acknowledgement so I went with the name hiruitus as well. Hessin has made significant contributions to Ontario paleontology and his work on "Fossils of South Western Ontario" is a must have and is still available for digital purchase directly from him. PM me if you need his contact information. 

The fear is that his Leviceraurus might be shuffled off. It very much depends on whether the Cheirurid revision is sourcing enough Canadian material. If it based mostly on US material, that might be problematic. And if it is based on cladistics, that might be a problem as well given how one can cherry-pick the morphologic characters. Brett and I have had long discussions about over-reliance on cladistic analysis.

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FossilDAWG

I'm not sure about "madonna and child", but it certainly is heavenly! :default_faint: :default_faint: :default_faint:

Don

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Malcolmt
2 hours ago, Kane said:

The fear is that his Leviceraurus might be shuffled off. It very much depends on whether the Cheirurid revision is sourcing enough Canadian material. If it based mostly on US material, that might be problematic. And if it is based on cladistics, that might be a problem as well given how one can cherry-pick the morphologic characters. Brett and I have had long discussions about over-reliance on cladistic analysis.

Well we certainly know where there is an Ontario plate of Levi's with lots of examples......

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3 minutes ago, Malcolmt said:

Well we certainly know where there is an Ontario plate of Levi's with lots of examples......

Yeah, I think we both know a guy… if not a permanent exhibit piece. :P 

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Randyw

Absolutely stunning! Excuse me while I empty my drool bucket!:drool:

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Sjfriend

Stunning work! 

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Superb!  Makes one want to start finding and prepping trilos!  

 

RB

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Paleorunner

uuuaaauuu !!!! that's a work of art.  : wub:: wub::babear:

 

Gabri finished.jpg

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another excellent specimen and excellent prepwork.   I think SVP will be in Toronto in the next few years, which means I will get a chance to see your amazing work.  I am looking forward to seeing these. 

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FossilNerd

What a beauty! :wub:

 

Excellent specimen and prep! 

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pachy-pleuro-whatnot-odon

In one word: stunning! :notworthy:

 

I'm not particularly a trilobite-guy myself, but this is something else! This should justly be called art! :default_clap2:

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