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Show us your Agnostids!


MeargleSchmeargl

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MeargleSchmeargl

I now have 2 slabs with Agnostids: One that I found last week, and one that I bought years ago at Fernbank Museum of Natural History. You know what to do: Show 'em if ya got 'em!

 

This is the hash slab I bought with some Agnostids and Elrathria:

 

_IMG_000000_000000.thumb.jpg.ed0b5d88c05a3c473249373caf6da9fd.jpg

 

And this is the Barrandagnostus inexpectans that I found last week up in Chatsworth. Probably my most proud find in the Conasauga shale:

 

IMG_20180405_114813.thumb.jpg.a89d11b995738e82c606f00b2ad892ed.jpg

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Ptychagnostus richmondensis occultatus (see post below) and Itagnostus interstrictus, both from the Wheeler shale.

D2F0628A-8D85-4AFF-838D-29A72F943AFD.jpeg

1656CC48-D7AA-4E7E-BFC4-688A258D0492.jpeg

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55 minutes ago, MeargleSchmeargl said:

2nd looks like a couple. :P

You can pretend it is you and your secret admirer.:hearty-laugh:

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56 minutes ago, Kane said:

 

1656CC48-D7AA-4E7E-BFC4-688A258D0492.jpeg

 

Love bugs :)

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2 hours ago, Kane said:

Ptychagnostus richmondensis and Itagnostus interstricta, both from the Wheeler shale.

 

These are the Wheeler Ptychagnostus species from Robison et al. 2015:

 

Ptychagnostus atavus

Ptychagnostus cuyanus

Ptychagnostus gibbus

Ptychagnostus occultatus

Ptychagnostus sinicus

 

Robison, R.A., Babcock, L.E., & Gunther, V.G. (2015)
Exceptional Cambrian fossils from Utah: A window into the age of trilobites.
Utah Geological Survey Miscellaneous Publication 15-1:1-97

 

 

Robison 1984 suppressed Ptychagnostus richmondensis:

 

"Although I (Robison, 1964:524) previously followed Palmer's (1954:61-62) appraisal of P. richmondensis, further collecting and review has led me to the conclusion that the species is unrecognizable...  ...Based on features shown in Walcott's (1884) original illustration, P. richmondensis may be a junior synonym of P. atavus, which is present in the Geddes Limestone (Robison, 1982); however, details are inadequate for confident identification...  ...Therefore, most specimens that I formerly assigned to P. richmondensis are here reassigned to P. occultatus."

 

Robison, R.A., (1984)

Cambrian Agnostida of North America and Greenland, Part 1, Ptychagnostidae.

University of Kansas Paleontological Contributions, 109:1-59   PDF LINK

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1 hour ago, piranha said:

 

These are the Wheeler Ptychagnostus species from Robison et al. 2015:

 

Ptychagnostus atavus

Ptychagnostus cuyanus

Ptychagnostus gibbus

Ptychagnostus occultatus

Ptychagnostus sinicus

 

Robison, R.A., Babcock, L.E., & Gunther, V.G. (2015)
Exceptional Cambrian fossils from Utah: A window into the age of trilobites.
Utah Geological Survey Miscellaneous Publication 15-1:1-97

 

 

Robison 1984 suppressed Ptychagnostus richmondensis:

 

"Although I (Robison, 1964:524) previously followed Palmer's (1954:61-62) appraisal of P. richmondensis, further collecting and review has led me to the conclusion that the species is unrecognizable...  ...Based on features shown in Walcott's (1884) original illustration, P. richmondensis may be a junior synonym of P. atavus, which is present in the Geddes Limestone (Robison, 1982); however, details are inadequate for confident identification...  ...Therefore, most specimens that I formerly assigned to P. richmondensis are here reassigned to P. occultatus."

 

Robison, R.A., (1984)

Cambrian Agnostida of North America and Greenland, Part 1, Ptychagnostidae.

University of Kansas Paleontological Contributions, 109:1-59   PDF LINK

Thanks! That is good to know... I'll be making some corrections to the database! :) (And thanks for the download link, too!). 

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MeargleSchmeargl
3 hours ago, Darktooth said:

You can pretend it is you and your secret admirer.:hearty-laugh:

And a secret it is! Note I left eventually was taken from my locker, and I never heard from the mysterious person again (for now). :headscratch:

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I have a slab or two somewhere in the garage that if I find I'll snap some more pics...in the meantime the only photo I can find is this tiny bug...

It was a purchase not a personal find. 

 

5acc2fb0859b5_PeronopsisinterstrictaUtah5closeup.thumb.jpg.9d72b714800027cc2a8c929cc0cac70f.jpg

Regards, Chris 

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Tidgy's Dad
20 hours ago, Plantguy said:

I have a slab or two somewhere in the garage that if I find I'll snap some more pics...in the meantime the only photo I can find is this tiny bug...

It was a purchase not a personal find. 

 

5acc2fb0859b5_PeronopsisinterstrictaUtah5closeup.thumb.jpg.9d72b714800027cc2a8c929cc0cac70f.jpg

Regards, Chris 

Nice! :)

Those are all agnostids

Do you know where they came from? 

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DevonianDigger

image.thumb.png.a28bc79157360feeb03a598addef5abc.png

 

~5mm

Itagnostus interstricta

Wheeler Fm.

Millard Co., Utah

Edited by DevonianDigger
mislabeled... again. :/
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Itagnostus interstricta did not stay at the Inn.  Fun with agnostids... lol emo71.gif emo31.gif

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DevonianDigger
21 minutes ago, piranha said:

Itagnostus interstricta did not stay at the Inn.  Fun with agnostids... lol emo71.gif emo31.gif

 

TriloBase auto-filled that one in for me, obviously this one from Utah is not from Australia. So yeah, Itagnostus would be correct. TriloBase is super convenient sometimes, and also good at helping me put my foot in my mouth. When I searched the DB for the Itagnostus, it went first to Innitagnostus, which looks pretty similar, so I didn't think twice when I clicked it. This will be the third time I am relabelling one of my most common trilobites... :doh!:

 

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DevonianDigger
1 minute ago, DevonianDigger said:

 

TriloBase auto-filled that one in for me, obviously this one from Utah is not from Australia. So yeah, Itagnostus would be correct. TriloBase is super convenient sometimes, and also good at helping me put my foot in my mouth. When I searched the DB for the Itagnostus, it went first to Innitagnostus, which looks pretty similar, so I didn't think twice when I clicked it. This will be the third time I am relabelling one of my most common trilobites... :doh!:

 

 

I take that back, now that I am really looking over the list in TriloBase, there is no listing for Itagnostus at all, yet the illustrations and citations listed for Innitagnostus are for Itagnostus. Still my fault, but I'm sad to discover that this DB is not as definitive as I was trusting it to be.

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Naimark 2012 includes I. interstricta and I. interstrictus, the latter being the current combination. 

 

Naimark, E.B. (2012)

Hundred species of the genus Peronopsis Hawle et Corda, 1847.

Paleontological Journal, 46(9):945-1057   PDF LINK

 

 

They are a confusing group.  I usually try to avoid them. :o :P

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On 4/9/2018 at 2:54 PM, MeargleSchmeargl said:

2nd looks like a couple. :P

Possible couple of couples

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And this is as good place as any to deepen an appreciation for these diminutive - and in the past somewhat controversial (in classification terms) - creatures. A rigorous and systematic phylogenetic analysis by Trevor Cotton and Richard Fortey is an absolute must-read for the agnostid connoisseur:

 

Cotton, T.J. & R.A. Fortey. 2005. Comparative morphology and relationships of the Agnostida appearing in Koenemann, S. & Jenner, R. (eds.). Crustacean Issues 16: Crustacea and Arthropod Relationships (CRC Press: Boca Raton)

 

I can't seem to locate a stand-alone link to the text, but interestingly enough that chapter appears almost in its entirety via GoogleBooks here

cottonfortey.jpeg

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DevonianDigger

I couldn't get more than the first 2 pages of the Cotton/Fortey paper from Google. I'll look for it elsewhere later.

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1 minute ago, DevonianDigger said:

I couldn't get more than the first 2 pages of the Cotton/Fortey paper from Google. I'll look for it elsewhere later.

That's bizarre... On this end, I was able to get the first four sections and a chunk of the Discussion. 

 

I just love the definitive last line of the abstract. No doubt about it to these esteemed trilobite experts: the Agnostida stay in Trilobita! No voting them off the clade! :D 

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I do have full access to Elena Naimark's paper, Ontogeny of Agnostida from Paleoworld 15 (2006), which is also a good read. The summary of the three competing hypotheses of the agnostid/eodiscid relationships is very succinct. 

 

 

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DevonianDigger

I have the Naimark paper, just have to read it, lol!

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Just now, DevonianDigger said:

I have the Naimark paper, just have to read it, lol!

That particular one? Naimark has an impressive publication list when it comes to Agnostida.

 

Piranha has a good bundle of them in his Open Access Trilobite Papers thread here, but this particular one is not open access. Elsevier, ya know... ;) 

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DevonianDigger
2 minutes ago, Kane said:

That particular one? Naimark has an impressive publication list when it comes to Agnostida.

 

Piranha has a good bundle of them in his Open Access Trilobite Papers thread here, but this particular one is not open access. Elsevier, ya know... ;) 

 

Good point, no, actually I have several, but not that one.

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